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1. But it is very likely that you do not have to do it as the resource should have the function you need It also has every single VISA foreign function in the underlying library as static method In code this means that you can do gt gt gt status ctypes c_ushort gt gt gt ret lib viReadSTB session ctypes byref status gt gt gt print ret value 26 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 Ask vs query Historically the method ask has been used in PyVISA to do a write followed by a read But in many other programs this operation is called query Thereby we have decided to switch the name keeping an alias to help with the transition However ask_for_values has not been aliased to query_values because the API is different ask_for_values still uses the old formatting API which is limited and broken We suggest that you migrate everything to query_values Seconds to milliseconds The timeout is now in milliseconds not in seconds as it was before The reason behind this change is to make it coherent with all other VISA implementations out there The C API LabVIEW NET all use milliseconds Using the same units not only makes it easy to migrate to PyVISA but also allows to profit from all other VISA docs out there without extra cognitive effort Removal of Instrument delay and added Instrument query_delay In the original PyVISA implementation Inst rume
2. gt gt gt inst term_chars r change it to gt gt gt inst read_termination r gt gt gt inst write_termination r If you are doing gt gt gt print lib status change it to gt gt gt print lib last_status or even better do it per resource gt gt gt print rm last_status for the resource manager gt gt gt print inst last_status for a specific instrument If you are doing gt gt gt inst timeout 1 Seconds change it to gt gt gt inst timeout 1000 Milliseconds As you see most of the code shown above is making a few things explict It adds 1 line of code instantiating the ResourceManager object which is not a big deal but it makes things cleaner 24 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 If you were using printf queryf scanf sprintf or sscanf of vpp43 rewrite as pure Python code see below If you were using Instrument delay change your code or use Instrument query_delay see below A few alias has been created to ease the transition e ask gt query e ask_delay gt query_delay get_instrument gt open_resource 3 2 2 A more detailed description Dropped support for string related functions The VISA library includes functions to search and manipulate strings such as printf queryf scanf sprintf and sscanf This makes sense as VI
3. 175 PyVISA Documentation Release 1 9 dev0 176 Python Module Index Index A AccessModes class in pyvisa constants 167 address_state pyvisa resources GPIB Interface attribute 126 AddressState class in pyvisa constants 168 allow_dma pyvisa resources GPIBInstrument attribute 117 allow_dma pyvisa resources GPIBInterface attribute 127 allow_dma pyvisa resources PXIInstrument attribute 139 allow_dma pyvisa resources SerialInstrument attribute 74 allow_dma pyvisa resources TCPIPInstrument attribute 84 allow_dma pyvisa resources VXIInstrument attribute 151 allow_dma pyvisa resources VXIMemory attribute 157 allow_transmit pyvisa resources SerialInstrument attribute 74 asrl pyvisa constants InterfaceType attribute 167 assert_interrupt_signal pyvisa highlevel VisaLibraryBase method 32 assert_trigger method 32 assert_trigger pyvisa resources GPIB Instrument method 117 assert_trigger pyvisa resources MessageBasedResource method 61 assert_trigger method 74 assert_trigger pyvisa resources TCPIPInstrument method 84 assert_trigger pyvisa resources TCPIPSocket method 92 assert_trigger method 99 assert_trigger pyvisa resources USBRaw method 109 assert_utility_signal pyvisa highlevel VisaLibraryBase method 33 pyvisa highlevel VisaLibrary Base pyvisa resources SerialInstrument pyvisa resources USBInstrument a
4. gt gt gt values np array inst query_ascii_values CURV but sometimes it is much more efficient to avoid the intermediate list and in this case you can just specify the container type in the query gt gt gt values inst query_ascii_values CURV container numpy array In container you can have any callable type that takes an iterable Some devices transfer data in ASCII but not as decimal numbers but rather hex or oct Or you might want to receive an array of strings In that case you can specify a converter For example if you expect to receive integers as hex gt gt gt values inst query_ascii_values CURV converter x converter can be one of the Python string formatting codes But you can also specify a callable that takes a single argument if needed The default converter is Finally some devices might return the values separated in an uncommon way For example if the returned values are separated by a you can do the following call gt gt gt values inst query_ascii_values CURV separator S You can provide a function to takes a string and returns an iterable Default value for the separator is comma 8 Chapter 2 User guide PyVISA Documentation Release 1 9 dev0 2 4 2 Reading binary values If your oscilloscope open in the variable inst has been configured to transfer data in BINARY when the CURV comm
5. Type class pyvisa constants AccessModes manufacturer_id VL ATTR_ MANE ID is the manufacturer identification number of the device VISA Attribute VI_ATTR_MANF_ID 1073676505 Type int Range 0 lt value lt 65535 manufacturer name This string attribute is the manufacturer name VISA Attribute VI_ATTR_MANF_NAME 3221160050 maximum_interrupt_size 3 6 API 111 PyVISA Documentation Release 1 9 dev0 VIATTR_USB_MAX_INTR_SIZE specifies the maximum size of data that will be stored by any given USB interrupt If a USB interrupt contains more data than this size the data in excess of this size will be lost VISA Attribute VI_ATTR_USB_MAX_INTR_SIZE 1073676719 Type int Range 0 lt value lt 65535 model_code VI_ATTR_MODEL_CODE specifies the model code for the device VISA Attribute VI_LATTR_MODEL_CODE 1073676511 Type int Range 0 lt value lt 65535 model_name This string attribute is the model name of the device VISA Attribute VI_ATTR_MODEL_NAME 3221160055 open access_mode lt AccessModes no_lock 0 gt open_timeout 5000 Opens a session to the specified resource Parameters access_mode pyvisa constants AccessModes Specifies the mode by which the resource is to be accessed e open_timeout int Milliseconds before the open operation times out query message delay None A combination of write message and read Parameters e message str the message to send e
6. Unique logical identifier to a session e primary address Primary address of the GPIB device to which you want to pass control e secondary address Secondary address of the targeted GPIB device If the tar geted device does not have a secondary address this parameter should contain the value Constants VI NO_SEC_ADDR Returns return value of the library call Return type pyvisa constants StatusCode gpib_send_ifc session Pulse the interface clear line IFC for at least 100 microseconds Corresponds to viGpibSendIFC function of the VISA library Parameters session Unique logical identifier to a session Returns return value of the library call Return type pyvisa constants StatusCode handlers None Contains all installed event handlers Its elements are tuples with three elements The handler itself a Python callable the user handle as a ct object and the handler again this time as a ct object created with CFUNCTYPE ignore_warning args kwds A session dependent context for ignoring warnings Parameters e session Unique logical identifier to a session 36 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 e warnings_constants constants identifying the warnings to ignore in_16 session space offset extended False Reads in an 16 bit value from the specified memory space and offset Corresponds to viln16 function of the VISA library Parameters e sess
7. e converter callable str function used to convert each value String formatting codes are also accepted Defaults to str e separator a callable that split the str into individual elements If a str is given data split separator is used Type separator collections Iterable T gt str str Returns number of bytes written Return type int write_binary values message values datatype u f is_big_endian False termination None encoding None Write a string message to the device followed by values in binary format The write_termination is always appended to it Parameters e message unicode Py2 or str Py3 the message to be sent e values data to be writen to the device e datatype the format string for a single element See struct module e is_big_endian boolean indicating endianess Returns number of bytes written Return type int write_raw message Write a byte message to the device Parameters message bytes the message to be sent Returns number of bytes written Return type int write termination Writer termination character write_values message values termination None encoding None class pyvisa resources RegisterBasedResource resource_manager resource_name Base class for resources that use register based communication before_close Called just before closing an instrument clear Clears this resource close Closes the VISA session and marks
8. e length Number of elements to transfer where the data width of the elements to transfer is identical to the source data width e data Data to write to bus e extended Use 64 bits offset independent of the platform Returns return value of the library call Return type pyvisa constants StatusCode Corresponds to viMoveOut8 function of the VISA library open session resource_name access_mode lt AccessModes no_lock 0 gt open_timeout 0 Opens a session to the specified resource Corresponds to viOpen function of the VISA library Parameters e session Resource Manager session should always be a session returned from open_default_resource_manager e resource_name Unique symbolic name of a resource e access_mode pyvisa constants AccessModes Specifies the mode by which the resource is to be accessed e open_timeout Specifies the maximum time period in milliseconds that this opera tion waits before returning an error Returns Unique logical identifier reference to a session return value of the library call Return type session opyvisa constants StatusCode open_default_resource_manager This function returns a session to the Default Resource Manager resource Corresponds to vidpenDefaultRM function of the VISA library 44 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 Returns Unique logical identifier to a Default Resource Manager session return value of
9. wait_on_event in_event_type timeout capture_timeout False Waits for an occurrence of the specified event in this resource Parameters e in_event_type Logical identifier of the event s to wait for e timeout Absolute time period in time units that the resource shall wait for a specified event to occur before returning the time elapsed error The time unit is in milliseconds None means waiting forever if necessary e capture_timeout When True will not produce a VisalOError VI_ERROR_TMO but instead return a WaitResponse with timed_out True Returns A WaitResponse object that contains event_type context and ret value 3 6 4 Constants module Provides user friendly naming to values used in different functions class pyvisa constants AccessModes exclusive_lock None Obtains a exclusive lock on the VISA resource no_lock None Does not obtain any lock on the VISA resource shared_lock None Obtains a lock on the VISA resouce which may be shared between multiple VISA sessions class pyvisa constants StopBits The number of stop bits that indicate the end of a frame class pyvisa constants Parity The parity types to use with every frame transmitted and received on a serial session class pyvisa constants SerialTermination The available methods for terminating a serial transfer last_bit None The transfer occurs with the last bit not set until the last character is sent none None The transfer termi
10. 105 read_stb pyvisa resources USBRaw method 113 read_termination pyvisa resources GPIBInstrument at tribute 122 read_termination pyvisa resources MessageBasedResource attribute 65 read_termination pyvisa resources SerialInstrument at tribute 80 pyvisa highlevel VisaLibraryBase pyvisa resources PXIInstrument Index 187 PyVISA Documentation Release 1 9 dev0 read_termination pyvisa resources TCPIPInstrument at tribute 88 read_termination pyvisa resources TCPIPSocket at tribute 96 read_termination pyvisa resources USBInstrument at tribute 105 read_termination pyvisa resources USBRaw attribute 113 read_termination_context pyvisa resources GPIBInstrument 122 read_termination_context pyvisa resources MessageBasedResource method 65 read_termination_context pyvisa resources SerialInstrument method 80 read_termination_context pyvisa resources TCPIPInstrument 88 read_termination_context pyvisa resources TCPIPSocket 96 read_termination_context pyvisa resources USBInstrument 105 read_termination_context method 113 read_to_file pyvisa highlevel VisaLibrary Base method 50 read_values pyvisa resources GPIBInstrument method 122 read_values pyvisa resources MessageBasedResource method 65 read_values method 80 read_values pyvisa resources TCPIPInstrument method 88 read_values pyvisa resources TCPIPSocket method
11. Parameters e access_mode pyvisa constants AccessModes Specifies the mode by which the resource is to be accessed e open_timeout int Milliseconds before the open operation times out read_memory space offset width extended False Reads in an 8 bit 16 bit 32 bit or 64 bit value from the specified memory space and offset Parameters e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e width Number of bits to read e extended Use 64 bits offset independent of the platform Returns Data read from memory Corresponds to viln functions of the visa library register interface_type resource_class resource _class VI_ATTR_RSRC_CLASS specifies the resource class for example INSTR as defined by the canonical resource name 148 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 VISA Attribute VI_ATTR_RSRC_CLASS 3221159937 resource_info Get the extended information of this resource Parameters resource_name Unique symbolic name of a resource Return type pyvisa highlevel ResourceInfo resource_manufacturer_name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for pr
12. Parameters name Resource attribute for which the state query is made see Attributes Returns The state of the queried attribute for a specified resource Return type unicode Py2 or str Py3 list or other type ignore_warning warnings_constants Ignoring warnings context manager for the current resource Parameters warnings_constants constants identifying the warnings to ignore implementation_version VI_ATTR_RSRC_IMPL_VERSION is the resource version that uniquely identifies each of the dif ferent revisions or implementations of a resource This attribute value is defined by the individual manufacturer and increments with each new revision The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version VISA Attribute VI_ATTR_RSRC_IMPL_VERSION 1073676291 Type int Range 0 lt value lt 4294967295 install_handler event_type handler user_handle None Installs handlers for event callbacks in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be installed by a client appli cation e user_handle A value specified by an application that can be used for identifying handlers uniquely for an event type 62 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 Returns user h
13. pyvisa highlevel VisaLibrary Base C chunk_size pyvisa resources GPIBInstrument attribute 117 chunk_size pyvisa resources MessageBasedResoutce at tribute 61 chunk_size pyvisa resources SerialInstrument attribute 75 chunk_size pyvisa resources TCPIPInstrument at tribute 84 chunk_size pyvisa resources TCPIPSocket attribute 92 chunk_size pyvisa resources USBInstrument attribute 99 chunk_size pyvisa resources USBRaw attribute 109 clear pyvisa highlevel VisaLibraryBase method 33 clear pyvisa resources FirewireInstrument method 134 clear pyvisa resources GPIBInstrument method 117 clear pyvisa resources GPIBInterface method 127 clear pyvisa resources MessageBasedResource method 61 clear pyvisa resources PXIInstrument method 139 clear pyvisa resources PXIMemory method 145 clear pyvisa resources RegisterBasedResource method 68 clear pyvisa resources Resource method 57 clear pyvisa resources SerialInstrument method 75 clear pyvisa resources TCPIPInstrument method 84 clear pyvisa resources TCPIPSocket method 92 clear pyvisa resources USBInstrument method 99 clear pyvisa resources USBRaw method 109 clear pyvisa resources V XIBackplane method 163 clear pyvisa resources V XIInstrument method 151 clear pyvisa resources VXIMemory method 157 close pyvisa highlevel ResourceManager method 55 close pyvisa high
14. pyvisa highlevel VisaLibrary Base lock pyvisa resources RegisterBasedResource method 70 lock pyvisa resources Resource method 58 lock pyvisa resources SerialInstrument method 77 lock pyvisa resources TCPIPInstrument method 86 lock pyvisa resources TCPIPSocket method 94 lock pyvisa resources USBInstrument method 102 lock pyvisa resources USBRaw method 111 lock pyvisa resources V XIBackplane method 164 lock pyvisa resources V XIInstrument method 153 lock pyvisa resources VXIMemory method 159 lock_context pyvisa resources FirewireInstrument method 135 lock_context pyvisa resources GPIBInstrument method 120 lock_context pyvisa resources GPIBInterface method 130 lock_context pyvisa resources MessageBasedResource method 63 lock_context pyvisa resources PXIInstrument method 141 lock_context pyvisa resources PXIMemory method 147 lock_context pyvisa resources RegisterBasedResource method 70 lock_context pyvisa resources Resource method 59 lock_context pyvisa resources SerialInstrument method 78 lock_context pyvisa resources TCPIPInstrument method 86 lock_context pyvisa resources TCPIPSocket method 94 lock_context method 102 lock_context pyvisa resources USBRaw method 111 lock_context pyvisa resources VXIBackplane method 164 lock_context method 153 lock_context pyvisa resources VXIMemory
15. 3 2 1 Short summary PyVISA 1 5 has full compatibility with previous versions of PyVISA using the legacy module changing some of the underlying implementation But you are encouraged to do a few things differently if you want to keep up with the latest developments and be compatible with PyVISA gt 1 5 Indeed PyVISA 1 6 breaks compatibility to bring across a few good things If you are doing gt gt gt import visa gt gt gt keithley visa instrument GPIB 12 gt gt gt print keithley ask IDN change it to gt gt gt import visa gt gt gt rm visa ResourceManager gt gt gt keithley rm open_resource GPIB 12 gt gt gt print keithley query IDN 3 2 Migrating from PyVISA lt 1 5 23 PyVISA Documentation Release 1 9 dev0 If you are doing gt gt gt print visa get_instruments_list change it to gt gt gt print rm list_resources If you are doing gt gt gt import pyvisa vpp43 as vpp43 gt gt gt vpp43 visa_library load_library path to my libvisa so 7 change it to gt gt gt import visa gt gt gt rm visa ResourceManager path to my libvisa so 7 gt gt gt lib rm visalib If you are doing gt gt gt vpp43 lock session change it to gt gt gt lib lock session or better gt gt gt resource lock If you are doing
16. 96 read_values pyvisa resources USBInstrument method 105 read_values pyvisa resources USBRaw method 113 register pyvisa resources FirewireInstrument method 137 register pyvisa resources GPIBInstrument 123 register pyvisa resources GPIBInterface method 131 register pyvisa resources MessageBasedResource method 65 register pyvisa resources PXIInstrument method 143 register pyvisa resources PXIMemory method 148 register pyvisa resources RegisterBasedResource method 71 register pyvisa resources Resource class method 59 method method method method pyvisa resources USBRaw pyvisa resources SerialInstrument method register pyvisa resources SerialInstrument method 80 register pyvisa resources TCPIPInstrument method 89 register pyvisa resources TCPIPSocket method 96 register pyvisa resources USBInstrument method 105 register pyvisa resources USBRaw method 114 register pyvisa resources V XIBackplane method 165 register pyvisa resources V XIInstrument method 154 register pyvisa resources VXIMemory method 160 RegisterBasedResource class in pyvisa resources 68 remote_enabled pyvisa resources GPIBInstrument at tribute 123 remote_enabled pyvisa resources GPIBInterface at tribute 131 replace_char pyvisa resources Seriallnstrument at tribute 80 Resource class in pyvisa resources 57 resource_class
17. After doing this you can simply call gt gt gt inst query_values CURV which will dispatch to the appropriate function and arguments If you want to default to ASCII transfer preconfiguring is a little bit more cumbersome as you need to specify the converters for both ways For example with hex with as separator gt gt gt inst values_format is_binary False gt gt gt inst values_format converter x gt gt gt inst values_format separator S gt gt gt inst values_format container numpy array or shorter gt gt gt inst values_format use_ascii x S numpy array This works for both query and write operations 2 4 6 When things are not what they should be PyVISA provides an easy way to transfer data from and to the device The methods described above work fine for 99 of the cases but there is always a particular device that do not follow any of the standard protocols and is so different that cannot be adapted with the arguments provided above In those cases you need to get the data gt gt gt inst write CURV gt gt gt data inst read_raw and then you need to implement the logic to parse it 2 5 A more complex example The following example shows how to use SCPI commands with a Keithley 2000 multimeter in order to measure 10 voltages After having read them the program calculates the average voltage and prints it on the scree
18. Defaults to self timeout e requested_key When using default of exclusive the lock is an exclusive lock Otherwise it is the access key for the shared lock or None to generate a new shared access key The returned context is the access_key if applicable lock_excl timeout u default Establish an exclusive lock to the resource Parameters timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout lock_state VIATTR_RSRC_LOCK_STATE indicates the current locking state of the resource The resource can be unlocked locked with an exclusive lock or locked with a shared lock VISA Attribute VI_ATTR_RSRC_LOCK_STATE 1073676292 Type class pyvisa constants AccessModes open access_mode lt AccessModes no_lock 0 gt open_timeout 5000 Opens a session to the specified resource Parameters e access_mode pyvisa constants AccessModes Specifies the mode by which the resource is to be accessed e open_timeout int Milliseconds before the open operation times out parity VI_ATTR_ASRL_PARITY is the parity used with every frame transmitted and received VISA Attribute VI_ATTR_ASRL_PARITY 1073676323 Type class pyvisa constants Parity query message delay None A combination of write message and read Parameters e message str the message to send e delay delay in seconds between write and rea
19. e fmt the format of the values If given it overrides the class attribute values_format Possible values are bitwise disjunctions of the above constants ascii single double and big_endian Default is ascii e container the output datatype Returns the list of read values Return type list register interface_type resource_class replace_char VIATTR_ASRL_REPLACE_CHAR specifies the character to be used to replace incoming charac ters that arrive with errors such as parity error VISA Attribute VI_ATTR_ASRL_REPLACE_CHAR 1073676478 Type int Range 0 lt value lt 255 resource_class VI_ATTR_RSRC_CLASS specifies the resource class for example INSTR as defined by the canonical resource name VISA Attribute VI_ATTR_RSRC_CLASS 3221159937 resource_info Get the extended information of this resource Parameters resource_name Unique symbolic name of a resource Return type pyvisa highlevel ResourceInfo resource_manufacturer_name 80 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 VI ATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_MANF
20. pyvisa resources TCPIPInstrument method 85 get_visa_attribute method 92 get_visa_attribute method 100 get_visa_attribute pyvisa resources USBRaw method 109 get_visa_attribute method 163 get_visa_attribute method 152 get_visa_attribute method 158 gpib pyvisa constants InterfaceType attribute 167 gpib_command pyvisa highlevel VisaLibrary Base method 35 pyvisa resources SerialInstrument pyvisa resources TCPIPSocket pyvisa resources USBInstrument pyvisa resources VXIBackplane pyvisa resources VXIInstrument pyvisa resources VXIMemory Index 181 PyVISA Documentation Release 1 9 dev0 gpib_control_atnQ method 35 gpib_control_ren method 36 gpib_pass_control method 36 gpib_send_ifc method 36 gpib_vxi pyvisa constants InterfaceType attribute 168 GPIBInstrument class in pyvisa resources 117 GPIBInterface class in pyvisa resources 126 group_execute_trigger pyvisa resources GPIBInterface method 128 pyvisa highlevel VisaLibrary Base pyvisa highlevel VisaLibrary Base pyvisa highlevel VisaLibrary Base pyvisa highlevel VisaLibrary Base H handlers pyvisa highlevel VisaLibraryBase attribute 36 hs488 pyvisa constants 1OProtocol attribute 168 ignore_warning method 36 ignore_warning pyvisa resources FirewireInstrument method 134 ignore_warning pyvisa resources GPIB Instrument method 119 ignore_warning
21. pyvisa resources FirewireInstrument method 134 enable_event pyvisa resources GPIB Instrument method 118 enable_event pyvisa resources GPIBInterface method 128 enable_event pyvisa resources MessageBasedResource method 62 enable_event method 140 enable_event pyvisa resources PXIMemory method 146 enable_event pyvisa resources RegisterBasedResource method 69 enable_event pyvisa resources Resource method 57 enable_event pyvisa resources SerialInstrument method 76 enable_event pyvisa resources TCPIPInstrument method 85 enable_event pyvisa resources TCPIPSocket method 92 enable_event method 100 enable_event pyvisa resources USBRaw method 109 enable_event pyvisa resources VXIBackplane method 163 enable_event method 152 enable_event pyvisa resources VXIMemory method 157 enable_repeat_addressing pyvisa resources GPIB Instrument 118 enable_unaddressing pyvisa resources GPIB Instrument attribute 118 encoding pyvisa resources GPIBInstrument attribute 118 encoding pyvisa resources MessageBasedResource at tribute 62 encoding pyvisa resources SerialInstrument attribute 76 encoding pyvisa resources TCPIPInstrument attribute 85 encoding pyvisa resources TCPIPSocket attribute 92 encoding pyvisa resources USBInstrument attribute 100 encoding pyvisa resources USBRaw attribute 109 end_input pyvisa resources SerialInstrume
22. INSTR More complex resource names can be specified with the following grammar VXI board VXI logical ad dress INSTR Do not instantiate directly use pyvisa highlevel ResourceManager open_resource allow_dma This attribute specifies whether I O accesses should use DMA VI_TRUE or Programmed I O VI_FALSE In some implementations this attribute may have global effects even though it is documented to be a local attribute Since this affects performance and not functionality that behavior is acceptable VISA Attribute VI_LATTR_DMA_ALLOW_EN 1073676318 Type bool before_close Called just before closing an instrument clear Clears this resource close Closes the VISA session and marks the handle as invalid destination_increment VI ATTR_DEST_INCREMENT is used in the viMoveOutXX operations to specify by how many elements the destination offset is to be incremented after every transfer The default value of this attribute is 1 that is the destination address will be incremented by 1 after each transfer and the viMoveOutXX operations move into consecutive elements If this attribute is set to 0 the viMove OutXX operations will always write to the same element essentially treating the destination as a FIFO register VISA Attribute VI_ATTR_DEST_INCREMENT 1073676353 Type int Range 0 lt value lt 1 disable_event event_type mechanism Disables notification of the specified event type s via the
23. before_close Called just before closing an instrument chunk_size 20480 clear Clears this resource close Closes the VISA session and marks the handle as invalid control_atn mode Specifies the state of the ATN line and the local active controller state Corresponds to viGpibControlATN function of the VISA library Parameters mode Specifies the state of the ATN line and optionally the local active controller state Constants GPIB_ATN Returns return value of the library call 3 6 API 117 PyVISA Documentation Release 1 9 dev0 Return type VISAStatus control_ren mode Controls the state of the GPIB Remote Enable REN interface line and optionally the remote local state of the device Corresponds to viGpibControlREN function of the VISA library Parameters mode Specifies the state of the REN line and optionally the device remote local state Constants GPIB_REN Returns return value of the library call Return type VISAStatus disable_event event_type mechanism Disables notification of the specified event type s via the specified mechanism s Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be disabled Con stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR VI_ALL_MECH discard_events event_type mechanism Discards event occurrences for specified event types and mechanisms in this resource Parameters e eve
24. can be unlocked locked with an exclusive lock or locked with a shared lock VISA Attribute VI_LATTR_RSRC_LOCK_STATE 1073676292 Type class pyvisa constants AccessModes 3 6 API 147 PyVISA Documentation Release 1 9 dev0 move_in space offset length width extended False Moves a block of data to local memory from the specified address space and offset Parameters e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read length Number of elements to transfer where the data width of the elements to transfer is identical to the source data width width Number of bits to read per element extended Use 64 bits offset independent of the platform move_out space offset length data width extended False Moves a block of data from local memory to the specified address space and offset Parameters e space Specifies the address space Constants SPACE offset Offset in bytes of the address or register from which to read length Number of elements to transfer where the data width of the elements to transfer is identical to the source data width data Data to write to bus width Number of bits to read per element extended Use 64 bits offset independent of the platform open access_mode lt AccessModes no_lock 0 gt open_timeout 5000 Opens a session to the specified resource
25. control both directions If XON XOFF flow control software handshaking is not being used the value of this attribute is ignored VISA Attribute VI_ATTR_ASRL_XON_CHAR 1073676481 Type int Range 0 lt value lt 255 class pyvisa resources TCPIPInstrument args kwargs Communicates with to devices of type TCPIP host address INSTR More complex resource names can be specified with the following grammar TCPIP board host ad dress LAN device name INSTR Do not instantiate directly use pyvisa highlevel ResourceManager open_resource CR w r LF w n allow_dma This attribute specifies whether I O accesses should use DMA VI_TRUE or Programmed I O VI_FALSE In some implementations this attribute may have global effects even though it is documented to be a local attribute Since this affects performance and not functionality that behavior is acceptable VISA Attribute VI_ATTR_DMA_ALLOW_EN 1073676318 Type bool assert_trigger Sends a software trigger to the device before_close Called just before closing an instrument chunk_size 20480 clear Clears this resource close Closes the VISA session and marks the handle as invalid control_ren mode Controls the state of the GPIB Remote Enable REN interface line and optionally the remote local state of the device Corresponds to viGpibControlREN function of the VISA library Parameters mode Specifies the stat
26. is_big_endian False termination None encoding None Write a string message to the device followed by values in binary format The write_termination is always appended to it Parameters e message unicode Py2 or str Py3 the message to be sent e values data to be writen to the device e datatype the format string for a single element See struct module e is_big_endian boolean indicating endianess Returns number of bytes written Return type int write_raw message Write a byte message to the device Parameters message bytes the message to be sent Returns number of bytes written Return type int write termination Writer termination character write_values message values termination None encoding None class pyvisa resources GPIBInterface resource_manager resource_name Communicates with to devices of type GPIB INTFC More complex resource names can be specified with the following grammar GPIB board INTFC Do not instantiate directly use pyvisa highlevel ResourceManager open_resource address_state 126 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 This attribute shows whether the specified GPIB interface is currently addressed to talk or listen or is not addressed VISA Attribute VI_ATTR_GPIB_ADDR_STATE 1073676380 Type class pyvisa constants AddressState allow_dma This attribute specifies whether I O accesses should use DMA VI_TRU
27. method 128 pyvisa highlevel VisaLibrary Base pyvisa resources GPIB Interface ignore_warning pyvisa resources MessageBasedResource method 62 ignore_warning method 140 ignore_warning method 146 pyvisa resources PXTInstrument pyvisa resources PXIMemory ignore_warning pyvisa resources RegisterBasedResource method 69 ignore_warning pyvisa resources Resource method 58 ignore_warning method 76 ignore_warning pyvisa resources TCPIPInstrument method 85 ignore_warning method 93 ignore_warning method 101 ignore_warning pyvisa resources USBRaw method 110 ignore_warning method 163 ignore_warning method 152 ignore_warning method 158 pyvisa resources SerialInstrument pyvisa resources TCPIPSocket pyvisa resources USBInstrument pyvisa resources VXIBackplane pyvisa resources VXIInstrument pyvisa resources V XIMemory implementation_version pyvisa resources FirewireInstrument attribute 134 implementation_version pyvisa resources GPIB Instrument attribute 119 implementation_version pyvisa resources GPIBInterface attribute 128 implementation_version pyvisa resources MessageBasedResource attribute 62 implementation_version pyvisa resources PXIInstrument attribute 140 implementation_version pyvisa resources PXIMemory attribute 146 implementation_version pyvisa resources RegisterBasedResource attribute 69 implementatio
28. pyvisa resources FirewireInstrument at tribute 137 resource_class pyvisa resources GPIBInstrument at tribute 123 resource_class pyvisa resources GPIBInterface at tribute 131 resource_class pyvisa resources MessageBasedResource attribute 65 resource_class pyvisa resources PXIInstrument at tribute 143 resource_class pyvisa resources PXIMemory attribute 148 resource_class pyvisa resources RegisterBasedResource attribute 71 resource_class pyvisa resources Resource attribute 59 resource_class pyvisa resources Seriallnstrument at tribute 80 resource_class pyvisa resources TCPIPInstrument attribute 89 resource_class pyvisa resources TCPIPSocket attribute 96 resource_class pyvisa resources USBInstrument at tribute 105 resource_class pyvisa resources USBRaw attribute 114 resource_class pyvisa resources VXIBackplane at tribute 165 resource_class pyvisa resources VXIInstrument at tribute 154 resource_class pyvisa resources VXIMemory attribute 160 resource_info pyvisa resources FirewireInstrument at tribute 137 resource_info pyvisa resources GPIBInstrument at tribute 123 resource_info pyvisa resources GPIBInterface attribute 131 188 Index PyVISA Documentation Release 1 9 dev0 resource_info pyvisa resources MessageBasedResource attribute 65 resource_info pyvisa resources PXIInstrument attribute 143 resource_info pyvisa resources PXIMe
29. requested_key None Establish a shared lock to the resource Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key Access key used by another session with which you want your ses sion to share a lock or None to generate a new shared access key Returns A new shared access key if requested_key is None otherwise same value as the re quested_key lock_context args kwds A context that locks Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key When using default of exclusive the lock is an exclusive lock Otherwise it is the access key for the shared lock or None to generate a new shared access key The returned context is the access_key if applicable lock_excl timeout u default Establish an exclusive lock to the resource Parameters timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout lock_state VIATTR_RSRC_LOCK_STATE indicates the current locking state of the resource The resource can be unlocked locked with an exclusive lock or locked with a shared lock VISA Attribute VI_ATTR_RSRC_LOCK_STATE 1073676292
30. wValue parameter of the setup stage of a USB control transfer index wIndex parameter of the setup stage of a USB control transfer This is usually the index of the interface or endpoint length wLength parameter of the setup stage of a USB control transfer This value also specifies the size of the data buffer to receive the data from the optional data stage of the control transfer Returns The data buffer that receives the data from the optional data stage of the control transfer Return type bytes control_ren mode Controls the state of the GPIB Remote Enable REN interface line and optionally the remote local state of the device Corresponds to viGpibControlREN function of the VISA library Parameters mode Specifies the state of the REN line and optionally the device remote local state Constants GPIB_REN Returns return value of the library call Return type VISAStatus disable_event event_type mechanism Disables notification of the specified event type s via the specified mechanism s Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be disabled Con stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR VI_ALL_MECH discard_events event_type mechanism Discards event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechani
31. 0 VI_ATTR_ASRL_ PARITY 1073676323 parity 0 VI_ATTR_ASRL_REPLACE_ CHAR 1073676478 replace_char 0 VI_A R_ASRL_RI_STATE 1073676479 0 VI_ATTR_ASRL_RTS_STATE 1073676480 al VI_ATTR_ASRL_STOP_BITS 1073676324 stop_bits 10 VI_ATTR_ASRL_WIRE_MODE 1073676735 128 VI_ATTR_ASRL_XOFF_CHAR 1073676482 xoff_char 19 VI_ATTR_ASRL_XON_CHAR 1073676481 xon_char 17 VI_ATTR_DMA_ALLOW_E 1073676318 allow_dma 0 VI_A R_FILE APPEND_E 1073676690 0 VI_ATTR_INTF_INST_NAME 3221160169 ASRL1 dev du Bluetooth l VI_ATTR_INTF_NU 1073676662 interface_number 1 VI_ATTR_INTF_TYPE 1073676657 4 VI_ATTR_IO_PROT 1073676316 io_protocol 1 VI_ATTR_MAX_QUEUE_LENGTH 1073676293 50 VI_ATTR_RD_BUF_OPER_MODE 1073676330 3 2 8 PyVISA Shell 17 PyVISA Documentation Release 1 9 dev0 VI_ATTR_RD_BUF_SIZE 1073676331 4096 VI_ATTR_RM_SESSIO 1073676484 3160976 VI_ATTR_RSRC_CLASS 3221159937 resource_class INSTR VI_ATTR_RSRC_IMPL_VERSION 1073676291 implementation_version 5243392 VI_ATTR_RSRC_LOCK_STATE 1073676292 lock_state 0 VI_ATTR_RSRC_MANF_ID 1073676661 4086 VI_ATTR_RSRC_MANF_NAME 3221160308 resource_manufacturer_name National Instrument VI_ATTR_RSRC_NAME 3221159938 resource_name A RL1 INSTR VI_ATTR_RSRC_SPEC_VERSION 1073676656 spec_version 5243136 VI_ATTR_SEND_END_FE 1073676310 send_end i VI_ATTR_SUPPRESS_END_EN 1
32. 3 6 API 65 PyVISA Documentation Release 1 9 dev0 resource_info Get the extended information of this resource Parameters resource_name Unique symbolic name of a resource Return type pyvisa highlevel ResourceInfo resource_manufacturer_name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_MANF_NAME 3221160308 resource _ name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_NAME 3221159938 session Resource session handle Raises pyvisa errors InvalidSession if session is closed set_visa_attribute name state Sets the state of an attribute Parameters e name Attribute for which the state is to be modified Attributes e state The state of the attribute to be set for the specified object spec_version VIATTR_RSRC_
33. Chapter 3 More information PyVISA Documentation Release 1 9 dev0 e requested_key When using default of exclusive the lock is an exclusive lock Otherwise it is the access key for the shared lock or None to generate a new shared access key The returned context is the access_key if applicable lock_excl timeout u default Establish an exclusive lock to the resource Parameters timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout lock_state VIATTR_RSRC_LOCK_STATE indicates the current locking state of the resource The resource can be unlocked locked with an exclusive lock or locked with a shared lock VISA Attribute VI_ATTR_RSRC_LOCK_STATE 1073676292 Type class pyvisa constants AccessModes open access_mode lt AccessModes no_lock 0 gt open_timeout 5000 Opens a session to the specified resource Parameters access_mode pyvisa constants AccessModes Specifies the mode by which the resource is to be accessed e open_timeout int Milliseconds before the open operation times out register interface_type resource_class resource_class VI_ATTR_RSRC_CLASS specifies the resource class for example INSTR as defined by the canonical resource name VISA Attribute VI_ATTR_RSRC_CLASS 3221159937 resource_info Get the extended information of this resource Parameters resource_na
34. Each backend exposes a class derived from VisaLibraryBase that implements the low level communication The ctypes wrapper around NI VISA is the default backend called ni and is bundled with PyVISA for simplicity You can specify the backend to use when you instantiate the resource manager using the symbol Remembering that ni is the default this 2 7 A frontend for multiple backends 13 PyVISA Documentation Release 1 9 dev0 gt gt gt import visa gt gt gt rm visa ResourceManager is the same as this gt gt gt import visa gt gt gt rm visa ResourceManager ni You can still provide the path to the library if needed gt gt gt import visa gt gt gt rm visa ResourceManager path to lib ni Under the hood the pyvisa highlevel ResourceManager looks for the requested backend and instantiate the VISA library that it provides PyVISA locates backends by name If you do gt gt gt import visa gt gt gt rm visa ResourceManager somename PyVISA will try to import a package module named pyvisa somename which should be installed in your system This is a loosly coupled configuration free method PyVISA does not need to know about any backend out there until you actually try to use it You can list the installed backends by running the following code in the command line python m visa info 2 7 1 Developing a new Backend Wh
35. Parameters e name Attribute for which the state is to be modified Attributes e state The state of the attribute to be set for the specified object spec_version VIATTR_RSRC_SPEC_VERSION is the resource version that uniquely identifies the version of the VISA specification to which the implementation is compliant The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the 3 6 API 137 PyVISA Documentation Release 1 9 dev0 version and the lowest 8 bits as the sub minor number of the version The current VISA specification defines the value to be 00300000h VISA Attribute VI_LATTR_RSRC_SPEC_VERSION 1073676656 Type int Range 0 lt value lt 4294967295 timeout The timeout in milliseconds for all resource I O operations Special values immediate VI_TMO_IMMEDTATE 0 for convenience any value smaller than 1 is considered as 0 infinite VI_TMO_INFINITE float inf for convenience None is considered as float inf To set an infinite timeout you can also use gt gt gt del instrument timeout uninstall_handler event_type handler user_handle None Uninstalls handlers for events in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be uninstalled by a client application e user_handle
36. Range 0 lt value lt 1 spec_version 3 6 API 149 PyVISA Documentation Release 1 9 dev0 VIATTR_RSRC_SPEC_VERSION is the resource version that uniquely identifies the version of the VISA specification to which the implementation is compliant The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version The current VISA specification defines the value to be 00300000h VISA Attribute VI_LATTR_RSRC_SPEC_VERSION 1073676656 Type int Range 0 lt value lt 4294967295 timeout The timeout in milliseconds for all resource I O operations Special values immediate VI_TMO_IMMEDIATE 0 for convenience any value smaller than 1 is considered as 0 einfinite VI_TMO_ INFINITE float inf for convenience None is considered as float inf To set an infinite timeout you can also use gt gt gt del instrument timeout uninstall_handler event_type handler user_handle None Uninstalls handlers for events in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be uninstalled by a client application e user_handle The user handle ctypes object or None returned by install_handler unlock Relinquishes a lock for the specified resource
37. Return type unicode Py2 or str Py3 list or other type ignore_warning warnings_constants Ignoring warnings context manager for the current resource Parameters warnings_constants constants identifying the warnings to ignore implementation_version VI_ATTR_RSRC_IMPL_VERSION is the resource version that uniquely identifies each of the dif ferent revisions or implementations of a resource This attribute value is defined by the individual manufacturer and increments with each new revision The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version VISA Attribute VI_ATTR_RSRC_IMPL_VERSION 1073676291 Type int Range 0 lt value lt 4294967295 install_handler event_type handler user_handle None Installs handlers for event callbacks in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be installed by a client appli cation e user_handle A value specified by an application that can be used for identifying handlers uniquely for an event type Returns user handle a ctypes object 140 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 interface_number VI_ATTR_INTF_NUM specifies the board number for the given interface VISA Attribute VI_ATTR_INTF_NUM 1073676662
38. SOCKET More complex resource names can be specified with the following grammar TCPIP board host ad dress port SOCKET Do not instantiate directly use pyvisa highlevel ResourceManager open_resource CR w r LF u n assert_trigger Sends a software trigger to the device before_close Called just before closing an instrument chunk_size 20480 clear Clears this resource close Closes the VISA session and marks the handle as invalid disable_event event_type mechanism Disables notification of the specified event type s via the specified mechanism s Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be disabled Con stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR VI_ALL_MECH discard_events event_type mechanism Discards event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be dicarded Con stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR VI_ALL_MECH enable_event event_type mechanism context None Enable event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be enabled Con stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR e context No
39. Testing your installation That s all You can check that PyVISA is correctly installed by starting up python and creating a ResourceManager gt gt gt import visa gt gt gt rm visa ResourceManager gt gt gt print rm list_resources If you encounter any problem take a look at the Frequently asked questions There you will find the solutions to common problem as well as useful debugging techniques If everything fails feel free to open an issue in our issue tracker 2 1 3 Using the development version You can install the latest development version at your own risk directly form GitHub PyVISA Documentation Release 1 9 dev0 pip install U https github com hgrecco pyvisa zipball master Note If you have an old system installation of Python and you don t want to mess with it you can try Anaconda CE It is a free Python distribution by Continuum Analytics that includes many scientific packages 2 2 Configuring the NI backend Note The NI backend requires that you install first the NI VISA library You can get info here V VISA Installation In most cases PyVISA will be able to find the location of the shared visa library If this does not work or you want to use another one you need to provide the library path to the pyvisa highlevel ResourceManager constructor gt gt gt rm ResourceManager Path to library You can make this library the
40. Type int Range 0 lt value lt 65535 interface_type The interface type of the resource as a number last_status Last status code for this session Return type pyvisa constants StatusCode lock timeout u default requested_key None Establish a shared lock to the resource Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key Access key used by another session with which you want your ses sion to share a lock or None to generate a new shared access key Returns A new shared access key if requested_key is None otherwise same value as the re quested_key lock_context args kwds A context that locks Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key When using default of exclusive the lock is an exclusive lock Otherwise it is the access key for the shared lock or None to generate a new shared access key The returned context is the access_key if applicable lock_excl timeout u default Establish an exclusive lock to the resource Parameters timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout lock_stat
41. USBRaw method 112 open pyvisa resources VXIBackplane method 165 open pyvisa resources VXIInstrument method 154 open pyvisa resources VXIMemory method 160 open_bare_resource pyvisa highlevel ResourceManager method 55 open_default_resource_manager pyvisa highlevel VisaLibraryBase method 44 open_resource pyvisa highlevel ResourceManager method 56 out_16 pyvisa highlevel VisaLibraryBase method 45 out_32 pyvisa highlevel VisaLibraryBase method 45 out_64 pyvisa highlevel VisaLibraryBase method 45 out_8 pyvisa highlevel VisaLibraryBase method 45 P Parity class in pyvisa constants 167 parity pyvisa resources SerialInstrument attribute 78 parse_resource pyvisa highlevel VisaLibrary Base method 46 parse_resource_extended pyvisa highlevel VisaLibraryBase method 46 pass_control pyvisa resources GPIB Instrument method 120 pass_control pyvisa resources GPIBInterface method 130 peek pyvisa highlevel VisaLibraryBase method 46 peek_16 pyvisa highlevel VisaLibraryBase method 47 peek_32 pyvisa highlevel VisaLibraryBase method 47 peek_64 pyvisa highlevel VisaLibraryBase method 47 peek_8 pyvisa highlevel VisaLibraryBase method 47 poke pyvisa highlevel VisaLibraryBase method 47 poke_16 pyvisa highlevel VisaLibraryBase method 48 poke_32 pyvisa highlevel VisaLibraryBase method 48 poke_64 pyvisa high
42. VXI you can choose normal word serial or fast data channel FDC In GPIB you can choose normal or high speed HS 488 transfers In serial TCPIP or USB RAW you can choose normal transfers or 488 2 defined strings In USB INSTR you can choose normal or vendor specific transfers VISA Attribute VI_ATTR_IO_PROT 1073676316 Type int Range 0 lt value lt 65535 is_controller_in_ charge This attribute shows whether the specified GPIB interface is currently CIC Controller In Charge VISA Attribute VI_ATTR_GPIB_CIC_STATE 1073676382 Type bool is_system_controller This attribute shows whether the specified GPIB interface is currently the system controller In some implementations this attribute may be modified only through a configuration utility On these systems this attribute is read only RO VISA Attribute VI_ATTR_GPIB_SYS_CNTRL_STATE 1073676392 Type bool last_status Last status code for this session Return type pyvisa constants StatusCode lock timeout u default requested_key None Establish a shared lock to the resource Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout 3 6 API 129 PyVISA Documentation Release 1 9 dev0 e requested_key Access key used by another session with which you want your ses sion to share a lock or None to generate a new shared acce
43. access key 3 6 API 153 PyVISA Documentation Release 1 9 dev0 The returned context is the access_key if applicable lock_excl timeout u default Establish an exclusive lock to the resource Parameters timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout lock_state VIATTR_RSRC_LOCK_STATE indicates the current locking state of the resource The resource can be unlocked locked with an exclusive lock or locked with a shared lock VISA Attribute VI_ATTR_RSRC_LOCK_STATE 1073676292 Type class pyvisa constants AccessModes manufacturer_id VL ATTR_ MANE ID is the manufacturer identification number of the device VISA Attribute VI_ATTR_MANF_ID 1073676505 Type int Range 0 lt value lt 65535 manufacturer name This string attribute is the manufacturer name VISA Attribute VI_ATTR_MANF_NAME 3221160050 model_code VI_ATTR_MODEL_CODE specifies the model code for the device VISA Attribute VI_ATTR_MODEL_CODE 1073676511 Type int Range 0 lt value lt 65535 model_name This string attribute is the model name of the device VISA Attribute VI_ATTR_MODEL_NAME 3221160055 open access_mode lt AccessModes no_lock 0 gt open_timeout 5000 Opens a session to the specified resource Parameters access_mode pyvisa constants AccessModes Specifies the mode by which the resource i
44. attribute 129 io_protocol pyvisa resources SerialInstrument attribute 77 io_protocol pyvisa resources TCPIPSocket attribute 93 io_protocol pyvisa resources USBInstrument attribute 101 io_protocol pyvisa resources USBRaw attribute 110 io_protocol pyvisa resources VXIInstrument attribute 153 1OProtocol class in pyvisa constants 168 is_4882_ compliant pyvisa resources USBInstrument at tribute 102 is_4882_ compliant pyvisa resources VXIInstrument at tribute 153 is_controller_in_charge pyvisa resources GPIBInterface attribute 129 is_system_controller pyvisa resources GPIB Interface at tribute 129 issue_warning_on pyvisa highlevel VisaLibraryBase at tribute 38 L last_bit pyvisa constants SerialTermination attribute 167 Index 183 PyVISA Documentation Release 1 9 dev0 last_status pyvisa highlevel ResourceManager attribute 55 last_status pyvisa highlevel VisaLibraryBase attribute 38 last_status pyvisa resources FirewireInstrument at tribute 135 last_status pyvisa resources GPIBInstrument attribute 120 pyvisa resources GPIBInterface attribute 129 last_status pyvisa resources MessageBasedResource at tribute 63 last_status pyvisa resources PXIInstrument 141 last_status pyvisa resources PXIMemory attribute 147 last_status pyvisa resources RegisterBasedResource at tribute 70 last_status pyvisa resources Resoutce attribute 58 l
45. channel FDC In GPIB you can choose normal or high speed HS 488 transfers In serial TCPIP or USB RAW you can choose normal transfers or 488 2 defined strings In USB INSTR you can choose normal or vendor specific transfers 3 6 API 119 PyVISA Documentation Release 1 9 dev0 VISA Attribute VI_ATTR_IO_PROT 1073676316 Type int Range 0 lt value lt 65535 last_status Last status code for this session Return type pyvisa constants StatusCode lock timeout u default requested_key None Establish a shared lock to the resource Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key Access key used by another session with which you want your ses sion to share a lock or None to generate a new shared access key Returns A new shared access key if requested_key is None otherwise same value as the re quested_key lock_context args kwds A context that locks Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key When using default of exclusive the lock is an exclusive lock Otherwise it is the access key for the shared lock or None to generate a new shared access key The returned context is the access_key if app
46. default for all PyVISA applications by using a configuration file called pyvisarc mind the leading dot in your home directory Operating System Location Windows NT lt root gt WINNT Profiles lt username gt Windows 2000 XP and 2003 lt root gt Documents and Settings lt username gt Windows Vista 7 or 8 lt root gt Users lt username gt Mac OS X Users lt username gt Linux home lt username gt depends on the distro For example in Windows XP place it in your user folder Documents and Settings folder e g C Documents and Settings smith pyvisarc if smith is the name of your login account This file has the format of an INI file For example if the library is at usr lib libvisa so 7 the file pyvisarc must contain the following Paths VISA library usr lib libvisa so 7 Please note that Paths is treated case sensitively You can define a site wide configuration file at usr share pyvisa pyvisarc It may also be usr local depending on the location of your Python Under Windows this file is usually placed at c Python27 share pyvisa pyvisarc If you encounter any problem take a look at the Frequently asked questions There you will find the solutions to common problem as well as useful debugging techniques If everything fails feel free to open an issue in our issue tracker 2 3 Tutorial Note If you have been using PyVISA before version 1 5
47. do not create this objects directly but they are returned by the pyvisa highlevel ResourceManager open_resource method of a pyvisa highlevel ResourceManager In general terms there are two main groups derived from pyvisa resources Resource pyvisa resources RegisterBasedResource and Pyvisa resources MessageBasedResource Note The resource Python class to use is selected automatically from the resource name However you can force a Resource Python class gt gt gt from pyvisa resources import MessageBasedResourc gt gt gt inst rm open ASRL1 INSTR resource_pyclass MessageBasedResource 2 6 Resources 11 PyVISA Documentation Release 1 9 dev0 The following sections explore the most common attributes of Resource and MessageBased Serial GPIB etc which are the ones you will encounte more often For more information refer to the API 2 6 1 Attributes Resource session Each communication channel to an instrument has a session handle which is unique You can get this value gt gt gt my_device session 10442240 If the resource is closed an exception will be raised gt gt gt inst close gt gt gt inst session Traceback most recent call last pyvisa errors InvalidSession Invalid session handle The resource might be closed timeout Very most VISA I O operations may be performed with a timeout If a timeout is
48. e container container type to use for the output data e delay delay in seconds between write and read operations if None defaults to self query_delay Return type bytes query delay 0 0 query_values message delay None Query the device for values returning an iterable of values The datatype expected is obtained from values_format Parameters e message str the message to send e delay delay in seconds between write and read operations if None defaults to self query_delay Returns the answer from the device Return type list 3 6 API 95 PyVISA Documentation Release 1 9 dev0 read termination None encoding None Read a string from the device Reading stops when the device stops sending e g by setting appropriate bus lines or the termination characters sequence was detected Attention Only the last character of the termination characters is really used to stop reading however the whole sequence is compared to the ending of the read string message If they don t match a warning is issued All line ending characters are stripped from the end of the string Return type str read_raw size None Read the unmodified string sent from the instrument to the computer In contrast to read no termination characters are stripped Return type bytes read_stb Service request status register read_termination Read termination character read_termination_context args kwds read_value
49. e width Number of bits to read e extended Use 64 bits offset independent of the platform Corresponds to viOut functions of the visa library class pyvisa resources VXIBackplane resource_manager resource_name Communicates with to devices of type VXI BACKPLANE 162 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 More complex resource names can be specified with the following grammar VXI board VXI logical address BACKPLANE Do not instantiate directly use pyvisa highlevel ResourceManager open_resource before_close Called just before closing an instrument clear Clears this resource close Closes the VISA session and marks the handle as invalid disable_event event_type mechanism Disables notification of the specified event type s via the specified mechanism s Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be disabled Con stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR VI_ALL_MECH discard_events event_type mechanism Discards event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be dicarded Con stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR VI_ALL_MECH enable_event event_type mechanism context None Enable event occurrences for specified event
50. for event callbacks in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be installed by a client appli cation e user_handle A value specified by an application that can be used for identifying handlers uniquely for an event type Returns user handle a ctypes object interface_number VI_ATTR_INTF_NUM specifies the board number for the given interface VISA Attribute VI_ATTR_INTF_NUM 1073676662 Type int Range 0 lt value lt 65535 interface_type The interface type of the resource as a number last_status Last status code for this session Return type pyvisa constants StatusCode lock timeout u default requested_key None Establish a shared lock to the resource Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key Access key used by another session with which you want your ses sion to share a lock or None to generate a new shared access key Returns A new shared access key if requested_key is None otherwise same value as the re quested_key lock_context args kwds A context that locks Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout 164
51. gt gt import visa gt gt gt rm visa ResourceManager path to my libvisa so 7 gt gt gt lib rm visalib assert_interrupt_signal session mode status_id Asserts the specified interrupt or signal Corresponds to viAssertIntrSignal function of the VISA library Parameters e session Unique logical identifier to a session e mode How to assert the interrupt Constants ASSERT e status_id This is the status value to be presented during an interrupt acknowledge cycle Returns return value of the library call Return type pyvisa constants StatusCode 32 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 assert_trigger session protocol Asserts software or hardware trigger Corresponds to viAssertTrigger function of the VISA library Parameters e session Unique logical identifier to a session e protocol Trigger protocol to use during assertion Constants PROT Returns return value of the library call Return type pyvisa constants StatusCode assert_utility_ signal session line Asserts or deasserts the specified utility bus signal Corresponds to viAssertUtilSignal function of the VISA library Parameters e session Unique logical identifier to a session e line specifies the utility bus signal to assert Constants VIL UTIL_ASSERT Returns return value of the library call Return type pyvisa constants StatusCode buffer_read session count Rea
52. in seconds between write and read operations self query_delay Return type bytes query delay 0 0 query_values message delay None Query the device for values returning an iterable of values The datatype expected is obtained from values_format Parameters e message str the message to send e delay delay in seconds between write and read operations self query_delay Returns the answer from the device Return type list read termination None encoding None Read a string from the device if None defaults to if None defaults to Reading stops when the device stops sending e g by setting appropriate bus lines or the termination characters sequence was detected Attention Only the last character of the termination characters is really used to stop reading however the whole sequence is compared to the ending of the read string message If they don t match a warning is issued All line ending characters are stripped from the end of the string Return type str read_raw size None Read the unmodified string sent from the instrument to the computer In contrast to read no termination characters are stripped Return type bytes read_stb Service request status register read_termination Read termination character read_termination_context args kwds 3 6 API 113 PyVISA Documentation Release 1 9 dev0 read_values fmt None container lt type list gt Read a list of fl
53. inf for convenience None is considered as float inf To set an infinite timeout you can also use gt gt gt del instrument timeout 3 6 API 97 PyVISA Documentation Release 1 9 dev0 uninstall_handler event_type handler user_handle None Uninstalls handlers for events in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be uninstalled by a client application e user_handle The user handle ctypes object or None returned by install_handler unlock Relinquishes a lock for the specified resource values_format visa_attributes_classes lt class pyvisa attributes AttrVI_ATTR_RM_SESSION gt lt class pyvisa attributes At wait_on_event in_event_type timeout capture_timeout False Waits for an occurrence of the specified event in this resource Parameters e in_event_type Logical identifier of the event s to wait for e timeout Absolute time period in time units that the resource shall wait for a specified event to occur before returning the time elapsed error The time unit is in milliseconds None means waiting forever if necessary e capture_timeout When True will not produce a VisalOError VI_LERROR_TMO but instead return a WaitResponse with timed_out True Returns A WaitResponse object that contains event_type context and ret value write message termination None e
54. keyword to establish communication with GPIB resources Use the VXI keyword for VXI resources via embedded MXIbus or 1394 controllers Use the ASRL keyword to establish communication with an asynchronous serial such as RS 232 or RS 485 device Use the PXI keyword for PXI and PCI resources Use the TCPIP keyword for Ethernet communication The following table shows the default value for optional string segments Optional String Segments Default Value board 0 GPIB secondary address none LAN device name instO PXI bus 0 PXI function 0 USB interface number lowest numbered relevant interface The following table shows examples of address strings 22 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 Address String Description ASRL 1 2 3 4 2 IN TR serial device attached to port 2 of the ENET Serial controller at address 1 2 3 4 ASRL1 INSTR A serial device attached to interface ASRLI GPIB 1 0 INSTR A GPIB device at primary address 1 and secondary address 0 in GPIB interface 0 GPIB2 INTFC Interface or raw board resource for GPIB interface 2 PXI 15 INSTR PXI device number 15 on bus 0 with implied function 0 PXI 2 BACKPLANE Backplane resource for chassis 2 on the default PXI system which is interface 0 PXI CHASSIS 1 SLOPXI device in slot number 3 of the PXI chassis configured as chassis 1 PXIO 2 PXI bus number 2 device 12 with f
55. libraries partly with free download These libraries work together with arbitrary peripherical devices although they may be limited to certain interface devices such as the vendor s GPIB card The VISA specification has explicit bindings to Visual Basic C and G LabVIEW s graphical language However you can use VISA with any language capable of calling functions in a shared library dll so dylib PyVISA is Python wrapper for such shared library and more PyVISA Documentation Release 1 9 dev0 4 Chapter 1 General overview CHAPTER 2 User guide 2 1 Installation PyVISA is a frontend to the VISA library It runs on Python 2 6 and 3 2 You can install it using pip pip install U pyvisa 2 1 1 NI Backend In order for Py VISA to work you need to have a suitable backend Py VISA includes a backend that wraps the National Instruments s VISA library However you need to download and install the library yourself See NJ VISA Installa tion There are multiple VISA implementations from different vendors PyVISA is tested only against National Instruments s VISA Warning PyVISA works with 32 and 64 bit Python and can deal with 32 and 64 bit VISA libraries without any extra configuration What PyVISA cannot do is open a 32 bit VISA library while running in 64 bit Python or the other way around You need to make sure that the Python and VISA library have the same bitness 2 1 2
56. lt type list gt de lay None header_fmt u ieee Converts an iterable of numbers into a block of data in the ieee format Parameters e message the message to send to the instrument e datatype the format string for a single element See struct module e is_big_endian boolean indicating endianess Defaults to False e container container type to use for the output data e delay delay in seconds between write and read operations if None defaults to self query_delay Return type bytes query delay 0 0 query_values message delay None Query the device for values returning an iterable of values The datatype expected is obtained from values_format Parameters e message str the message to send e delay delay in seconds between write and read operations if None defaults to self query_delay Returns the answer from the device Return type list read termination None encoding None Read a string from the device Reading stops when the device stops sending e g by setting appropriate bus lines or the termination characters sequence was detected Attention Only the last character of the termination characters is really used to stop reading however the whole sequence is compared to the ending of the read string message If they don t match a warning is issued All line ending characters are stripped from the end of the string Return type str read_raw size None Read the unmodified
57. method 159 lock_excl pyvisa resources FirewireInstrument method 135 lock_excl pyvisa resources GPIBInstrument method 120 lock_excl pyvisa resources GPIBInterface method 130 lock_excl _ pyvisa resources MessageBasedResource method 63 lock_excl pyvisa resources PXIInstrument method 141 lock_excl pyvisa resources PXIMemory method 147 lock_excl pyvisa resources RegisterBasedResource method 70 pyvisa resources USBInstrument pyvisa resources VXIInstrument 184 Index PyVISA Documentation Release 1 9 dev0 lock_excl pyvisa resources Resource method 59 lock_excl pyvisa resources SerialInstrument method 78 lock_excl pyvisa resources TCPIPInstrument method 86 lock_excl pyvisa resources TCPIPSocket method 94 lock_excl pyvisa resources USBInstrument method 102 lock_excl pyvisa resources USBRaw method 111 lock_excl pyvisa resources VXIBackplane method 165 lock_exclQ pyvisa resources VXIInstrument method 154 lock_excl pyvisa resources VXIMemory method 159 lock_state pyvisa resources FirewireInstrument at tribute 136 lock_state pyvisa resources GPIBInstrument attribute 120 pyvisa resources GPIBInterface 130 lock_state pyvisa resources MessageBasedResource at tribute 63 lock_state pyvisa resources PXIInstrument 141 lock_state pyvisa resources PXIMemory attribute 147 lock_state pyvisa resources Register
58. of a USB control transfer index wIndex parameter of the setup stage of a USB control transfer This is usually the index of the interface or endpoint e data The data buffer that sends the data in the optional data stage of the control transfer usb_protocol VI_ATTR_USB_PROTOCOL specifies the USB protocol used by this USB interface VISA Attribute VI_ATTR_USB_PROTOCOL 1073676711 Type int Range 0 lt value lt 255 values_format visa_attributes_classes lt class pyvisa attributes AttrVI_ATTR_RM_SESSION gt lt class pyvisa attributes At wait_on_event in_event_type timeout capture_timeout False Waits for an occurrence of the specified event in this resource Parameters e in_event_type Logical identifier of the event s to wait for e timeout Absolute time period in time units that the resource shall wait for a specified event to occur before returning the time elapsed error The time unit is in milliseconds None means waiting forever if necessary e capture_timeout When True will not produce a VisalOError VI_ERROR_TMO but instead return a WaitResponse with timed_out True Returns A WaitResponse object that contains event_type context and ret value 3 6 API 107 PyVISA Documentation Release 1 9 dev0 write message termination None encoding None Write a string message to the device The write_termination is always appended to it Parameters message unicode Py2 or str P
59. of the elements to transfer is identical to the source data width e data Data to write to bus e extended Use 64 bits offset independent of the platform Returns return value of the library call Return type pyvisa constants StatusCode move_out_64 session space offset length data extended False Moves an 64 bit block of data from local memory to the specified address space and offset Corresponds to viMoveOut64 functions of the VISA library Parameters e session Unique logical identifier to a session 3 6 API 43 PyVISA Documentation Release 1 9 dev0 e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e length Number of elements to transfer where the data width of the elements to transfer is identical to the source data width e data Data to write to bus e extended Use 64 bits offset independent of the platform Returns return value of the library call Return type pyvisa constants StatusCode move_out_8 session space offset length data extended False Moves an 8 bit block of data from local memory to the specified address space and offset Corresponds to viMoveOut8 functions of the VISA library Parameters e session Unique logical identifier to a session e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read
60. particular session Parameters session Unique logical identifier to a session If None operates on all sessions uninstall_handler session event_type handler user_handle None Uninstalls handlers for events Corresponds to viUninstallHandler function of the VISA library Parameters e session Unique logical identifier to a session e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be uninstalled by a client application e user_handle A value specified by an application that can be used for identifying handlers uniquely in a session for an event Returns return value of the library call Return type pyvisa constants StatusCode uninstall_visa_handler session event_type handler user_handle None Uninstalls handlers for events Parameters e session Unique logical identifier to a session e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be uninstalled by a client application e user_handle The user handle ctypes object or None returned by in stall_ visa_handler 3 6 API 51 PyVISA Documentation Release 1 9 dev0 unlock session Relinquishes a lock for the specified resource Corresponds to viUnlock function of the VISA library Parameters session Unique logical identifier to a session Returns return value of the library call Return type pyvisa constants StatusCode unmap_addre
61. resources Resourc resource_info resource_name extended True Get the extended information of a particular resource Parameters resource_name Unique symbolic name of a resource Return type pyvisa highlevel ResourceInfo session Resource Manager session handle Raises pyvisa errors InvalidSession if session is closed 3 6 3 Resource classes Resources are high level abstractions to managing specific sessions An instance of one of these classes is returned by the open_resource depending on the resource type Generic classes e Resource e MessageBasedResourc e RegisterBasedResourc Specific Classes e SerialInstrument e TCPIPInstrument e TCPIPSocket e USBInstrument 56 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 USBRaw GPIBInstrument GPIBInterface FirewireInstrument PXIInstrument PXIInstrument VxXIInstrument VXI Memory VXI Backplane class pyvisa resources Resource resource_manager resource_name Base class for resources Do not instantiate directly use pyvisa highlevel ResourceManager open_resource Parameters e resource_manager A resource manager instance e resource_name the VISA name for the resource eg GPIB 10 before_close Called just before closing an instrument clear Clears this resource close Closes the VISA session and marks the handle as invalid disable_event event_type mechanism Disables n
62. session space offset extended False Reads in an 8 bit value from the specified memory space and offset Corresponds to viln8 function of the VISA library Parameters e session Unique logical identifier to a session e space Specifies the address space Constants SPACE 3 6 API 37 PyVISA Documentation Release 1 9 dev0 e offset Offset in bytes of the address or register from which to read e extended Use 64 bits offset independent of the platform Returns Data read from memory return value of the library call Return type int pyvisa constants StatusCode install_handler session event_type handler user_handle Installs handlers for event callbacks Corresponds to vilnstallHandler function of the VISA library Parameters e session Unique logical identifier to a session e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be installed by a client appli cation e user_handle A value specified by an application that can be used for identifying handlers uniquely for an event type Returns a handler descriptor which consists of three elements handler a python callable user handle a ctypes object ctypes handler ctypes object wrapping handler and return value of the library call Return type int pyvisa constants StatusCode install_visa_handler session event_type handler user_handle None Installs handlers for event callb
63. set every operation that takes longer than the timeout is aborted and an exception is raised Timeouts are given per instrument in milliseconds For all PyVISA objects a timeout is set with my_device timeout 25000 Here my_device may be a device an interface or whatever and its timeout is set to 25 seconds To set an infinite timeout set it to None or float inf or del my_device timeout To set it to immediate set it to 0 or a negative value Actually any value smaller than 1 is considered immediate Now every operation of the resource takes as long as it takes even indefinitely if necessary 2 6 2 Attributes of MessageBase resources Chunk length If you read data from a device you must store it somewhere Unfortunately Py VISA must make space for the data before it starts reading which means that it must know how much data the device will send However it doesn t know a priori Therefore PyVISA reads from the device in chunks Each chunk is 20 kilobytes long by default If there s still data to be read PyVISA repeats the procedure and eventually concatenates the results and returns it to you Those 20 kilobytes are large enough so that mostly one read cycle is sufficient The whole thing happens automatically as you can see Normally you needn t worry about it However some devices don t like to send data in chunks So if you have trouble with a certain device and expect data length
64. specified event type s via the specified mechanism s 3 6 API 127 PyVISA Documentation Release 1 9 dev0 Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be disabled stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR VI_ALL_MECH discard_events event_type mechanism Discards event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be dicarded stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR VI_ALL_MECH enable_event event_type mechanism context None Enable event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be enabled stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR e context Not currently used leave as None get_visa_attribute name Retrieves the state of an attribute in this resource Con Con Con Parameters name Resource attribute for which the state query is made see Attributes Returns The state of the queried attribute for a specified resource Return type unicode Py2 or str Py3 list or other type group_execute_trigger resources ignore_warning warnings_constants Ignoring warnings context manager for the current resource Parameters warnin
65. specified mechanism s Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be disabled Con stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR VI_ALL_MECH 3 6 API 151 PyVISA Documentation Release 1 9 dev0 discard_events event_type mechanism Discards event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be dicarded Con stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR VI_ALL_MECH enable event event_type mechanism context None Enable event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be enabled Con stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR e context Not currently used leave as None get_visa_attribute name Retrieves the state of an attribute in this resource Parameters name Resource attribute for which the state query is made see Attributes Returns The state of the queried attribute for a specified resource Return type unicode Py2 or str Py3 list or other type ignore_warning warnings_constants Ignoring warnings context manager for the current resource Parameters warnings_constants constants identifying the warnings to ignore implementatio
66. state of the resource The resource can be unlocked locked with an exclusive lock or locked with a shared lock VISA Attribute VI ATTR_RSRC_LOCK_STATE 1073676292 Type class pyvisa constants AccessModes manufacturer_id VI_ATTR_MANF ID is the manufacturer identification number of the device VISA Attribute VI _ATTR_MANF_ID 1073676505 102 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 Type int Range 0 lt value lt 65535 manufacturer_name This string attribute is the manufacturer name VISA Attribute VI_LATTR_MANF_NAME 3221160050 maximum_interrupt_size VIATTR_USB_MAX_INTR_SIZE specifies the maximum size of data that will be stored by any given USB interrupt If a USB interrupt contains more data than this size the data in excess of this size will be lost VISA Attribute VI_ATTR_USB_MAX_INTR_SIZE 1073676719 Type int Range 0 lt value lt 65535 model_code VI_ATTR_MODEL_CODE specifies the model code for the device VISA Attribute VI_ATTR_MODEL_CODE 1073676511 Type int Range 0 lt value lt 65535 model_name This string attribute is the model name of the device VISA Attribute VI_ATTR_MODEL_NAME 3221160055 open access_mode lt AccessModes no_lock 0 gt open_timeout 5000 Opens a session to the specified resource Parameters e access_mode pyvisa constants AccessModes Specifies the mode by which the resource is to be accessed e open_timeout i
67. the handle as invalid disable_event event_type mechanism Disables notification of the specified event type s via the specified mechanism s Parameters 68 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be disabled Con stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR VI_ALL_MECH discard_events event_type mechanism Discards event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be dicarded Con stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR VI_ALL_MECH enable_event event_type mechanism context None Enable event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be enabled Con stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR e context Not currently used leave as None get_visa_attribute name Retrieves the state of an attribute in this resource Parameters name Resource attribute for which the state query is made see Attributes Returns The state of the queried attribute for a specified resource Return type unicode Py2 or str Py3 list or other type ignore_warning warnings_constants Ignoring
68. the library call Return type VISAStatus primary address VI ATTR_GPIB_PRIMARY_ADDR specifies the primary address of the GPIB device used by the given session For the GPIB INTFC Resource this attribute is Read Write VISA Attribute VI_ATTR_GPIB_PRIMARY_ADDR 1073676658 Type int Range 0 lt value lt 30 query message delay None A combination of write message and read Parameters e message str the message to send e delay delay in seconds between write and read operations if None defaults to self query_delay Returns the answer from the device Return type str query _ascii_values message converter u f separator u container lt type list gt de lay None Query the device for values in ascii format returning an iterable of values Parameters e message str the message to send e delay delay in seconds between write and read operations if None defaults to self query_delay converter callable function used to convert each element Defaults to float separator a callable that split the str into individual elements If a str is given data split separator is used e container container type to use for the output data Type separator str gt collections Iterable int str Returns the answer from the device Return type list 3 6 API 121 PyVISA Documentation Release 1 9 dev0 query_binary values message datatype u f is_big_endian False container
69. types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be enabled Con stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR e context Not currently used leave as None get_visa_attribute name Retrieves the state of an attribute in this resource Parameters name Resource attribute for which the state query is made see Attributes Returns The state of the queried attribute for a specified resource Return type unicode Py2 or str Py3 list or other type ignore_warning warnings_constants Ignoring warnings context manager for the current resource Parameters warnings_constants constants identifying the warnings to ignore implementation_version VIATTR_RSRC_IMPL_VERSION is the resource version that uniquely identifies each of the dif ferent revisions or implementations of a resource This attribute value is defined by the individual manufacturer and increments with each new revision The format of the value has the upper 12 bits as 3 6 API 163 PyVISA Documentation Release 1 9 dev0 the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version VISA Attribute VI_LATTR_RSRC_IMPL_VERSION 1073676291 Type int Range 0 lt value lt 4294967295 install_handler event_type handler user_handle None Installs handlers
70. value to be 00300000h VISA Attribute VI_ATTR_RSRC_SPEC_VERSION 1073676656 Type int Range 0 lt value lt 4294967295 stb Service request status register timeout The timeout in milliseconds for all resource I O operations Special values immediate VI_TMO_IMMEDIATE 0 for convenience any value smaller than 1 is considered as 0 infinite VI_TMO_INFINITE float inf for convenience None is considered as float inf To set an infinite timeout you can also use 106 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 gt gt gt del instrument timeout uninstall_handler event_type handler user_handle None Uninstalls handlers for events in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be uninstalled by a client application e user_handle The user handle ctypes object or None returned by install_handler unlock Relinquishes a lock for the specified resource usb_control_out request_type_bitmap_field request_id request_value index data u Performs a USB control pipe transfer to the device Parameters request_type_bitmap_field bmRequestType parameter of the setup stage of a USB control transfer request_id bRequest parameter of the setup stage of a USB control transfer request_value wValue parameter of the setup stage
71. warnings context manager for the current resource Parameters warnings_constants constants identifying the warnings to ignore implementation_version VIATTR_RSRC_IMPL_VERSION is the resource version that uniquely identifies each of the dif ferent revisions or implementations of a resource This attribute value is defined by the individual manufacturer and increments with each new revision The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version VISA Attribute VI_ATTR_RSRC_IMPL_VERSION 1073676291 Type int Range 0 lt value lt 4294967295 install_handler event_type handler user_handle None Installs handlers for event callbacks in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be installed by a client appli cation 3 6 API 69 PyVISA Documentation Release 1 9 dev0 e user_handle A value specified by an application that can be used for identifying handlers uniquely for an event type Returns user handle a ctypes object interface_number VI_ATTR_INTF_NUM specifies the board number for the given interface VISA Attribute VI_ATTR_INTF_NUM 1073676662 Type int Range 0 lt value lt 65535 interface_type The interface type of the resource as a number last_status Last st
72. 073676342 0 VI_ATTR_TERMCHAR 1073676312 10 VI_ATTR_TERMCHAR_E 1073676344 0 VI_ATTR_TMO_VALUE 1073676314 2000 VI_ATTR_TRIG_ID 1073676663 1 VI_ATTR_WR_BUF_OPER_MODE 1073676333 2 VI_ATTR_WR_BUF_SIZE 1073676334 4096 na ae a J Finally you can close the device open close Cool right It will be great to have a GUI similar to NI MAX but we leave that to be developed outside PyVISA Want to help Let us know 2 9 Architecture PyVISA implements convenient and Pythonic programming in three layers 1 Low level A wrapper around the shared visa library The wrapper defines the argument types and response types of each function as well as the conversions between Python objects and foreign types You will normally not need to access these functions directly If you do it probably means that we need to improve layer 2 All level 1 functions are static methods of pyvisa highlevel VisaLibrary Warning Notice however that low level functions might not be present in all backends For broader compatibility do no use this layer All the functionality should is available via the next layer Middle level A wrapping Python function for each function of the shared visa library These functions call the low level functions adding some code to deal with type conversions for functions that return values by reference These functions also have comprehensive and Python friendly documentation You only need to ac
73. 1 INSTR 1 ASRL2 INSTR 2 USBO 0x1AB1 0x0588 DS1K00005888 INSTR Each device port is assigned a number that you can use for subsequent commands Let s open comport 1 visa open 0 ASRL1 INSTR has been opened You can talk to the device using write read or query The default end of message is added to open query IDN Some Instrument Some Company ach messag We can also get a list of all visa attributes VISA name Constant Python name val VI_ATTR_ASRL_ALLOW_TRANSMIT 1073676734 allow_transmit 1 VI_ATTR_ASRL_AVAIL_NU 1073676460 bytes_in_buffer 0 VI_ATTR_ASRL_BAUD 1073676321 baud_rate 9600 VI_ATTR_ASRL_BREAK_LE 1073676733 break_length 250 VI_ATTR_ASRL_BREAK STATE 1073676732 break_state O VI_LA R_ASRL_CONNECTED 1073676731 VI_ERROR_NSUP_ATTI VI_ATTR_ASRL_CTS_STATE 1073676462 0 VI_A R_ASRL_DATA_ BITS 1073676322 data_bits 8 VI_ATTR_ASRL_DCD_STATE 1073676463 0 VI_ATTR_ASRL_DISCARD_NULL 1073676464 discard_null O VI_A R_ASRL_DSR_STATE 1073676465 0 VI_ATTR_ASRL_DTR_STATE 1073676466 1 VI_ATTR_ASRL_END_IN 1073676467 end_input 2 VI_ATTR_ASRL_END_OUT 1073676468 0 VI_ATTR_ASRL_FLOW_CNTRL 1073676325
74. 292 Type class pyvisa constants AccessModes open access_mode lt AccessModes no_lock 0 gt open_timeout 5000 Opens a session to the specified resource Parameters access_mode pyvisa constants AccessModes Specifies the mode by which the resource is to be accessed e open_timeout int Milliseconds before the open operation times out classmethod register interface_type resource_class resource _class VI_ATTR_RSRC_CLASS specifies the resource class for example INSTR as defined by the canonical resource name VISA Attribute VI_ATTR_RSRC_CLASS 3221159937 resource_info Get the extended information of this resource Parameters resource_name Unique symbolic name of a resource Return type pyvisa highlevel ResourceInfo 3 6 API 59 PyVISA Documentation Release 1 9 dev0 resource_manufacturer_name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_MANF_NAME 3221160308 resource _ name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the devi
75. 42 move_out pyvisa resources FirewireInstrument method 136 move_out pyvisa resources PXIInstrument method 142 move_out pyvisa resources PXIMemory method 148 move_out pyvisa resources RegisterBasedResource method 71 move_out pyvisa resources VXIMemory method 159 move_out_16 pyvisa highlevel VisaLibrary Base method 43 move_out_32 method 43 move_out_64 method 43 move_out_8 method 44 pyvisa highlevel VisaLibrary Base pyvisa highlevel VisaLibrary Base pyvisa highlevel VisaLibrary Base N ndac_state pyvisa resources GPIBInterface attribute 130 no_lock pyvisa constants AccessModes attribute 167 none pyvisa constants SerialTermination attribute 167 O open pyvisa highlevel VisaLibraryBase method 44 open pyvisa resources FirewireInstrument method 136 open pyvisa resources GPIBInstrument method 120 open pyvisa resources GPIBInterface method 130 open pyvisa resources MessageBasedResource method 63 open pyvisa resources PXIInstrument method 142 open pyvisa resources PXIMemory method 148 open pyvisa resources RegisterBasedResource method 71 open pyvisa resources Resource method 59 open pyvisa resources SerialInstrument method 78 open pyvisa resources TCPIPInstrument method 87 open pyvisa resources TCPIPSocket method 94 open pyvisa resources USBInstrument method 103 open pyvisa resources
76. 8 bits as the sub minor number of the version VISA Attribute VI_ATTR_RSRC_IMPL_VERSION 1073676291 Type int Range 0 lt value lt 4294967295 install_handler event_type handler user_handle None Installs handlers for event callbacks in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be installed by a client appli cation e user_handle A value specified by an application that can be used for identifying handlers uniquely for an event type Returns user handle a ctypes object interface_number VI_ATTR_INTF_NUM specifies the board number for the given interface VISA Attribute VI_ATTR_INTF_NUM 1073676662 Type int Range 0 lt value lt 65535 interface_type The interface type of the resource as a number io_protocol VI_ATTR_IO_PROT specifies which protocol to use In VXI you can choose normal word serial or fast data channel FDC In GPIB you can choose normal or high speed HS 488 transfers In serial TCPIP or USB RAW you can choose normal transfers or 488 2 defined strings In USB INSTR you can choose normal or vendor specific transfers VISA Attribute VI_ATTR_IO_PROT 1073676316 Type int Range 0 lt value lt 65535 last_status Last status code for this session 110 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 Return type pyvisa constants StatusCode lock timeout u default
77. BasedResource at tribute 70 lock_state pyvisa resources Resource attribute 59 lock_state pyvisa resources SerialInstrument attribute 78 lock_state pyvisa resources TCPIPInstrument attribute 86 lock_state pyvisa resources TCPIPSocket attribute 94 lock_state pyvisa resources USBInstrument attribute 102 lock_state pyvisa resources USBRaw attribute 111 lock_state pyvisa resources VXIBackplane attribute 165 lock_state pyvisa resources VXIInstrument 154 lock_state pyvisa resources VXIMemory attribute 159 M manufacturer_id pyvisa resources PXIInstrument at tribute 141 manufacturer_id pyvisa resources USBInstrument attribute 102 manufacturer_id pyvisa resources USBRaw attribute 111 manufacturer_id attribute 154 manufacturer_name pyvisa resources PXIInstrument at tribute 142 lock_ state attribute attribute attribute pyvisa resources V XIInstrument manufacturer_name pyvisa resources USBInstrument at tribute 103 manufacturer_name tribute 111 manufacturer_name pyvisa resources V XIInstrument at tribute 154 map_address method 39 map_trigger method 39 maximum_interrupt_size pyvisa resources USBInstrument 103 maximum _interrupt_size pyvisa resources USBRaw at tribute 111 memory_allocation pyvisa highlevel VisaLibraryBase method 39 memory_free method 40 MessageBasedResoutce class in pyvisa resources 61 model_cod
78. E or Programmed I O VI_FALSE In some implementations this attribute may have global effects even though it is documented to be a local attribute Since this affects performance and not functionality that behavior is acceptable VISA Attribute VI_ATTR_DMA_ALLOW_EN 1073676318 Type bool atn_state This attribute shows the current state of the GPIB ATN ATtentioN interface line VISA Attribute VI_ATTR_GPIB_ATN_STATE 1073676375 Type class pyvisa constants LineState before_close Called just before closing an instrument clear Clears this resource close Closes the VISA session and marks the handle as invalid control_atn mode Specifies the state of the ATN line and the local active controller state Corresponds to viGpibControlATN function of the VISA library Parameters mode Specifies the state of the ATN line and optionally the local active controller state Constants GPIB_ATN Returns return value of the library call Return type VISAStatus control_ren mode Controls the state of the GPIB Remote Enable REN interface line and optionally the remote local state of the device Corresponds to viGpibControlREN function of the VISA library Parameters mode Specifies the state of the REN line and optionally the device remote local state Constants GPIB_REN Returns return value of the library call Return type VISAStatus disable_event event_type mechanism Disables notification of the
79. EDTATE 0 for convenience any value smaller than 1 is considered as 0 infinite VI_TMO_ INFINITE float inf for convenience None is considered as float inf To set an infinite timeout you can also use gt gt gt del instrument timeout uninstall_handler event_type handler user_handle None Uninstalls handlers for events in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be uninstalled by a client application e user_handle The user handle ctypes object or None returned by install_handler unlock Relinquishes a lock for the specified resource values_format visa_attributes_classes lt class pyvisa attributes AttrVI_ATTR_RM_SESSION gt lt class pyvisa attributes At wait_for_srq timeout 25000 Wait for a serial request SRQ coming from the instrument Note that this method is not ended when another instrument signals an SRQ only this instrument Parameters timeout the maximum waiting time in milliseconds Defaul 25000 millisec onds None means waiting forever if necessary wait_on_event in_event_type timeout capture_timeout False Waits for an occurrence of the specified event in this resource Parameters e in_event_type Logical identifier of the event s to wait for e timeout Absolute time period in time units that the resource shall wait for
80. EN specifies whether to assert END during the transfer of the last byte of the buffer VISA Attribute VI_ATTR_SEND_END_EN 1073676310 Type bool send_ifc Pulse the interface clear line IFC for at least 100 microseconds Corresponds to viGpibSendIFC function of the VISA library Returns return value of the library call Return type VISAStatus session Resource session handle Raises pyvisa errors InvalidSession if session is closed set_visa_attribute name state Sets the state of an attribute Parameters e name Attribute for which the state is to be modified Attributes e state The state of the attribute to be set for the specified object spec_version VI_ATTR_RSRC_SPEC_VERSION is the resource version that uniquely identifies the version of the VISA specification to which the implementation is compliant The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version The current VISA specification defines the value to be 00300000h VISA Attribute VI_LATTR_RSRC_SPEC_VERSION 1073676656 Type int Range 0 lt value lt 4294967295 stb Service request status register 124 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 timeout The timeout in milliseconds for all resource I O operations Special values immediate VI_TMO_IMM
81. ISA Attribute VI_ATTR_INTF_NUM 1073676662 Type int Range 0 lt value lt 65535 interface_type The interface type of the resource as a number io_protocol VI_ATTR_IO_PROT specifies which protocol to use In VXI you can choose normal word serial or fast data channel FDC In GPIB you can choose normal or high speed HS 488 transfers In serial TCPIP or USB RAW you can choose normal transfers or 488 2 defined strings In USB INSTR you can choose normal or vendor specific transfers VISA Attribute VI_ATTR_IO_PROT 1073676316 Type int Range 0 lt value lt 65535 last_status Last status code for this session Return type pyvisa constants StatusCode lock timeout u default requested_key None Establish a shared lock to the resource Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout 3 6 API 77 PyVISA Documentation Release 1 9 dev0 e requested_key Access key used by another session with which you want your ses sion to share a lock or None to generate a new shared access key Returns A new shared access key if requested_key is None otherwise same value as the re quested_key lock_context args kwds A context that locks Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error
82. I_LTRUE NUL characters are discarded Otherwise they are treated as normal data char acters For binary transfers set this attribute to VI_FALSE VISA Attribute VI_ATTR_ASRL_DISCARD_NULL 1073676464 Type bool enable_event event_type mechanism context None Enable event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be enabled Con stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR e context Not currently used leave as None encoding Encoding used for read and write operations end_input VIATTR_ASRL_END_IN indicates the method used to terminate read operations VISA Attribute VI_ATTR_ASRL_END_IN 1073676467 Type class pyvisa constants SerialTermination flow_control VI ATTR_ASRL_FLOW_CNTRL indicates the type of flow control used by the transfer mecha nism VISA Attribute VI_ATTR_ASRL_FLOW_CNTRL 1073676325 Type int Range 0 lt value lt 65535 flush mask Manually clears the specified buffers and cause the buffer data to be written to the device Parameters mask Specifies the action to be taken with flushing the buffer Con stants READ WRITE 10 get_visa_attribute name Retrieves the state of an attribute in this resource Parameters name Resource attribute for which the state query is made see Attributes Returns The state of the
83. LF w n assert_trigger Sends a software trigger to the device before_close Called just before closing an instrument chunk_size 20480 clear Clears this resource close Closes the VISA session and marks the handle as invalid disable_event event_type mechanism Disables notification of the specified event type s via the specified mechanism s Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be disabled Con stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR VI_ALL_MECH 3 6 API 61 PyVISA Documentation Release 1 9 dev0 discard_events event_type mechanism Discards event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be dicarded Con stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR VI_ALL_MECH enable event event_type mechanism context None Enable event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be enabled Con stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR e context Not currently used leave as None encoding Encoding used for read and write operations get_visa_attribute name Retrieves the state of an attribute in this resource
84. Number of elements to transfer where the data width of the elements to transfer is identical to the source data width data Data to write to bus width Number of bits to read per element extended Use 64 bits offset independent of the platform open access_mode lt AccessModes no_lock 0 gt open_timeout 5000 Opens a session to the specified resource Parameters e access_mode pyvisa constants AccessModes Specifies the mode by which the resource is to be accessed e open_timeout int Milliseconds before the open operation times out read_memory space offset width extended False Reads in an 8 bit 16 bit 32 bit or 64 bit value from the specified memory space and offset Parameters e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e width Number of bits to read e extended Use 64 bits offset independent of the platform Returns Data read from memory Corresponds to viln functions of the visa library register interface_type resource_class resource class VI_ATTR_RSRC_CLASS specifies the resource class for example INSTR as defined by the canonical resource name VISA Attribute VI_ATTR_RSRC_CLASS 3221159937 resource_info Get the extended information of this resource Parameters resource_name Unique symbolic name of a resource Return type pyvisa highlevel ResourceInfo resource_manu
85. OError VI_ERROR_TMO but instead return a WaitResponse with timed_out True Returns A WaitResponse object that contains event_type context and ret value write_memory space offset data width extended False Write in an 8 bit 16 bit 32 bit value to the specified memory space and offset Parameters e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e data Data to write to bus e width Number of bits to read e extended Use 64 bits offset independent of the platform Corresponds to viOut functions of the visa library 3 6 API 73 PyVISA Documentation Release 1 9 dev0 class pyvisa resources SerialInstrument args kwargs Communicates with devices of type ASRL lt board gt INSTR Do not instantiate directly use pyvisa highlevel ResourceManager open_resource CR w r LF w n allow_dma This attribute specifies whether I O accesses should use DMA VI_TRUE or Programmed I O VI_FALSE In some implementations this attribute may have global effects even though it is documented to be a local attribute Since this affects performance and not functionality that behavior is acceptable VISA Attribute VI_LATTR_DMA_ALLOW_EN 1073676318 Type bool allow_transmit If set to VI_LFALSE it suspends transmission as if an XOFF character has been received If set to VI_TRUE it resumes transmission as if a
86. PEND_HNDLR VI_ALL_MECH enable event event_type mechanism context None Enable event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be enabled Con stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR e context Not currently used leave as None get_visa_attribute name Retrieves the state of an attribute in this resource Parameters name Resource attribute for which the state query is made see Attributes Returns The state of the queried attribute for a specified resource Return type unicode Py2 or str Py3 list or other type ignore_warning warnings_constants Ignoring warnings context manager for the current resource Parameters warnings_constants constants identifying the warnings to ignore implementation_version VIATTR_RSRC_IMPL_VERSION is the resource version that uniquely identifies each of the dif ferent revisions or implementations of a resource This attribute value is defined by the individual manufacturer and increments with each new revision The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version VISA Attribute VI_ATTR_RSRC_IMPL_VERSION 1073676291 Type int 134 Chapter 3 More information PyVISA Docu
87. PyVISA Documentation Release 1 9 dev0 PyVISA Authors October 14 2015 Contents 1 General overview 3 2 User guide 5 2A Installation sos E ora oe 42S oe alee ee ROR aR Eee Hae Ee ae ee ee we ead E 5 2 2 Confisurmp the NI Backend ss gns i e soni aa eS aS as A R E R 6 23 Tutofal e 225384 2686 ee a bee Pa bee bade R E E ea Sad oat A 6 24 Reading and Writing values 2 0 5 6 6 a AA RE ee EO Re ee 8 23 Amofe complexexample ce ecs 6 4 44 0 48 44484400 ee Sea De bbe ed ERE E 10 26 IRESOUNCC Sis ccs arane tee eas idna dort a Gi e A E hove abt dees ee AE E av teehee aes et ce BH ae Goede es te aah te 11 27 d atrontend tor multiple backends 5 2 ge Sas be Soe Lae ee bk eee eee 13 2 8 PyVISA Shell 2 5 2s40 e 5 4225 PAG Dt a e ES eee Sets aeeee he eadud 16 29 Architect re fee ee Be ee oe EAE ME eGR eee BAe Oa OE Sees 18 3 More information 21 3 1 VISA resource Names oi be a Ae ee a a e 21 3 2 Migrating from Py VISA lt 13 ne gai ee ee i a ey ak Be Ge ay aS 23 3 3 Contnibutingto Py VISA ss ses ee ea AR Oa ee Oe a Gwe a a aa 27 34 Brequentlyasked questions codes eo eee BG Bae eta ke BAS ee Dare amp Sue amp 28 33 NEVISA Installation e 555 eae a Gee seks ee eee eee eee EE Ye Re 31 20 ABM 3 uae Ui eee eat ba ee ea hee ee 2 ee ee 32 Python Module Index 175 PyVISA Documentation Release 1 9 dev0 A PyVISA PyVISA is a Python package that enables you to control all kinds of measurement devices indepe
88. Raw query_binary_values pyvisa resources MessageBasedResoaade memory method 64 query_binary_values pyvisa resources SerialInstrument method 79 query_binary_values pyvisa resources TCPIPInstrument method 87 query_binary_values method 95 query_binary_values pyvisa resources USBInstrument method 104 query_binary_values method 113 query_delay 13 query_delay pyvisa resources GPIBInstrument tribute 122 query_delay pyvisa resources MessageBasedResource attribute 64 pyvisa resources TCPIPSocket pyvisa resources USBRaw at query_delay pyvisa resources SerialInstrument at tribute 79 query_delay pyvisa resources TCPIPInstrument at tribute 88 query_delay pyvisa resources TCPIPSocket attribute 95 query_delay pyvisa resources USBInstrument attribute 104 query_delay pyvisa resources USBRaw attribute 113 query_values pyvisa resources GPIB Instrument method 122 query_values pyvisa resources MessageBasedResource method 64 query_values method 79 query_values pyvisa resources TCPIPInstrument method 88 query_values pyvisa resources TCPIPSocket method 95 query_values method 104 query_values pyvisa resources USBRaw method 113 R read pyvisa highlevel VisaLibraryBase method 49 pyvisa resources SerialInstrument pyvisa resources USBInstrument read pyvisa resources GPIBInstrument method 122 read pyvisa r
89. SA Documentation Release 1 9 dev0 flush session mask Manually flushes the specified buffers associated with formatted I O operations and or serial communica tion Corresponds to viFlush function of the VISA library Parameters e session Unique logical identifier to a session e mask Specifies the action to be taken with flushing the buffer Constants READ WRITE 1O Returns return value of the library call Return type pyvisa constants StatusCode get_attribute session attribute Retrieves the state of an attribute Corresponds to viGetAttribute function of the VISA library Parameters e session Unique logical identifier to a session event or find list e attribute Resource attribute for which the state query is made see Attributes Returns The state of the queried attribute for a specified resource return value of the library call Return type unicode Py2 or str Py3 list or other type Pyvisa constants StatusCode static get_debug_info Override this method to return an iterable of lines with the backend debug details get_last_status_in_session session Last status in session Helper function to be called by resources properties static get_library paths Override this method to return an iterable of possible library_paths to try in case that no argument is given gpib_command session data Write GPIB command bytes on the bus Corresponds to viGpibCommand function of t
90. SA involves a lot of string handling operations The original PyVISA imple mentation wrapped these functions But these operations are easily expressed in pure python and therefore were rarely used PyVISA 1 5 keeps these functions for backwards compatibility but they are removed in 1 6 We suggest that you replace such functions by a pure Python version Isolated low level wrapping module In the original PyVISA implementation the low level implementation vpp43 was mixed with higher level con structs The VISA library was wrapped using ctypes In 1 5 we refactored it as ctwrapper This allows us to test the foreign function calls by isolating them from higher level abstractions More importantly it also allows us to build new low level modules that can be used as drop in replacements for ctwrapper in high level modules In 1 6 we made the ResourceManager the object exposed to the user The type of the VisaLibrary can selected depending of the 1ibrary_path and obtained from a plugin package We have two of such packages planned e a Mock module that allows you to test a PyVISA program even if you do not have VISA installed e a CFFI based wrapper CFFI is new python package that allows easier and more robust wrapping of foreign libraries It might be part of Python in the future PyVISA 1 5 keeps vpp43 in the legacy subpackage reimplemented on top of ct wrapper to help with the migra tion This module is gone in 1 6 All fun
91. SPEC_VERSION is the resource version that uniquely identifies the version of the VISA specification to which the implementation is compliant The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version The current VISA specification defines the value to be 00300000h VISA Attribute VILATTR_RSRC_SPEC_VERSION 1073676656 Type int Range 0 lt value lt 4294967295 stb Service request status register 66 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 timeout The timeout in milliseconds for all resource I O operations Special values immediate VI_TMO_IMMEDTATE 0 for convenience any value smaller than 1 is considered as 0 infinite VI_TMO_ INFINITE float inf for convenience None is considered as float inf To set an infinite timeout you can also use gt gt gt del instrument timeout uninstall_handler event_type handler user_handle None Uninstalls handlers for events in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be uninstalled by a client application e user_handle The user handle ctypes object or None returned by install_handler unlock Relinquishes a lock for the specified resource val
92. ST_INCREMENT 1073676353 Type int Range 0 lt value lt 1 disable_event event_type mechanism Disables notification of the specified event type s via the specified mechanism s 3 6 API 145 PyVISA Documentation Release 1 9 dev0 Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be disabled Con stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR VI_ALL_MECH discard_events event_type mechanism Discards event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be dicarded Con stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR VI_ALL_MECH enable_event event_type mechanism context None Enable event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be enabled Con stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR e context Not currently used leave as None get_visa_attribute name Retrieves the state of an attribute in this resource Parameters name Resource attribute for which the state query is made see Attributes Returns The state of the queried attribute for a specified resource Return type unicode Py2 or str Py3 list or other type ignore_warning warnings_co
93. The user handle ctypes object or None returned by install_handler unlock Relinquishes a lock for the specified resource visa_attributes_classes lt class pyvisa attributes AttrVI_ATTR_RM_SESSION gt lt class pyvisa attributes At wait_on_event in_event_type timeout capture_timeout False Waits for an occurrence of the specified event in this resource Parameters e in_event_type Logical identifier of the event s to wait for e timeout Absolute time period in time units that the resource shall wait for a specified event to occur before returning the time elapsed error The time unit is in milliseconds None means waiting forever if necessary e capture_timeout When True will not produce a VisalOError VI_ERROR_TMO but instead return a WaitResponse with timed_out True Returns A WaitResponse object that contains event_type context and ret value write_memory space offset data width extended False Write in an 8 bit 16 bit 32 bit value to the specified memory space and offset Parameters e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read 138 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 e data Data to write to bus e width Number of bits to read e extended Use 64 bits offset independent of the platform Corresponds to viOut functions of the visa library c
94. Windows 8 x64 Edition 64 bit version Windows 8 32 bit version Windows 7 x64 Edition 64 bit version Windows 7 32 bit version Windows Vista x64 Edition 64 bit version Windows Vista 32 bit version Windows XP Service Pack 3 Support for Windows Server 2003 R2 may require disabling physical address extensions PAE 3 5 NI VISA Installation 31 PyVISA Documentation Release 1 9 dev0 3 5 3 Linux Download NI VISA for Linux Supports openSUSE 12 2 openSUSE 12 1 Red Hat Enterprise Linux Desktop Workstation 6 Red Hat Enterprise Linux Desktop Workstation 5 Scientific Linux 6 x Scientific Linux 5 x Currently only 32 bit applications are supported on the x86 64 architecture Note NI VISA runs on other linux distros but the installation is more cumbersome 3 6 API 3 6 1 Visa Library class pyvisa highlevel VisaLibraryBase Base for VISA library classes A class derived from VisaLibraryBase library provides the low level communication to the underlying devices providing Pythonic wrappers to VISA functions But not all derived class must will implement all methods The default VisaLibrary class is pyvisa ctwrapper highlevel NIVisaLibrary which implements a ctypes wrapper around the NI VISA library In general you should not instantiate it directly The object exposed to the user is the pyvisa highlevel ResourceManager If needed you can access the VISA library from it gt
95. _NAME 3221160308 resource _ name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_NAME 3221159938 send_end VIATTR_SEND_END_EN specifies whether to assert END during the transfer of the last byte of the buffer VISA Attribute VI_ATTR_SEND_END_EN 1073676310 Type bool session Resource session handle Raises pyvisa errors InvalidSession if session is closed set_visa_attribute name state Sets the state of an attribute Parameters e name Attribute for which the state is to be modified Attributes e state The state of the attribute to be set for the specified object spec_version VIATTR_RSRC_SPEC_VERSION is the resource version that uniquely identifies the version of the VISA specification to which the implementation is compliant The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version The current VISA specification defines the value to be 00300000h VISA Attribute VILATTR_RSRC_SPEC_VERSION 1073676656 Type in
96. _key if applicable lock_excl timeout u default Establish an exclusive lock to the resource Parameters timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout lock_state VIATTR_RSRC_LOCK_STATE indicates the current locking state of the resource The resource can be unlocked locked with an exclusive lock or locked with a shared lock VISA Attribute VI_ATTR_RSRC_LOCK_STATE 1073676292 Type class pyvisa constants AccessModes move_in space offset length width extended False Moves a block of data to local memory from the specified address space and offset Parameters e space Specifies the address space Constants SPACE offset Offset in bytes of the address or register from which to read length Number of elements to transfer where the data width of the elements to transfer is identical to the source data width width Number of bits to read per element extended Use 64 bits offset independent of the platform 3 6 API 159 PyVISA Documentation Release 1 9 dev0 move_out space offset length data width extended False Moves a block of data from local memory to the specified address space and offset Parameters e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read length
97. a resources RegisterBasedResource attribute 72 spec_version pyvisa resources Resource attribute 60 spec_version pyvisa resources SerialInstrument at tribute 81 spec_version pyvisa resources TCPIPInstrument at tribute 89 spec_version pyvisa resources TCPIPSocket attribute 97 spec_version pyvisa resources USB Instrument attribute 106 spec_version pyvisa resources USBRaw attribute 115 spec_version pyvisa resources V XIBackplane attribute 166 spec_version pyvisa resources VXIInstrument attribute 156 spec_version pyvisa resources VXIMemory attribute 161 status_description method 50 StatusCode class in pyvisa constants 168 stb pyvisa resources GPIBInstrument attribute 124 stb pyvisa resources MessageBasedResource attribute 66 stb pyvisa resources SerialInstrument attribute 81 stb pyvisa resources TCPIPInstrument attribute 90 stb pyvisa resources TCPIPSocket attribute 97 stb pyvisa resources USBInstrument attribute 106 stb pyvisa resources USBRaw attribute 115 stop_bits pyvisa resources SerialInstrument attribute 81 StopBits class in pyvisa constants 167 success pyvisa constants StatusCode attribute 172 success_device_not_present pyvisa constants StatusCode attribute 172 success_event_already_disabled pyvisa constants StatusCode attribute 172 success_event_already_enabled pyvisa constants StatusCode attribute 172 success_max_count_read
98. a resources USBInstrument at tribute 101 interface_type pyvisa resources USBRaw attribute 110 interface_type pyvisa resources VXIBackplane at tribute 164 interface_type pyvisa resources VXIInstrument at tribute 153 interface_number pyvisa resources MessageBasedResourceinterface_type pyvisa resources VXIMemory attribute attribute 63 interface_number pyvisa resources PXIInstrument at tribute 140 interface_number pyvisa resources PXIMemory at tribute 147 interface_number pyvisa resources RegisterBasedResource attribute 70 interface_number pyvisa resources Resource attribute 58 interface_number pyvisa resources SerialInstrument at tribute 77 interface_number pyvisa resources TCPIPInstrument at tribute 86 interface_number pyvisa resources TCPIPSocket at tribute 93 interface_number pyvisa resources USBInstrument at tribute 101 interface_number pyvisa resources USBRaw attribute 110 interface_number pyvisa resources VXIBackplane at tribute 164 interface_number pyvisa resources VXIInstrument at tribute 152 interface_number pyvisa resources VXIMemory at tribute 158 interface_type pyvisa resources FirewireInstrument at tribute 135 interface_type pyvisa resources GPIBInstrument at tribute 119 158 InterfaceType class in pyvisa constants 167 io_protocol pyvisa resources GPIBInstrument attribute 119 io_protocol pyvisa resources GPIBInterface
99. a specified event to occur before returning the time elapsed error The time unit is in milliseconds None means waiting forever if necessary e capture_timeout When True will not produce a VisalOError VI_ERROR_TMO but instead return a WaitResponse with timed_out True Returns A WaitResponse object that contains event_type context and ret value write message termination None encoding None Write a string message to the device The write_termination is always appended to it Parameters message unicode Py2 or str Py3 the message to be sent Returns number of bytes written 3 6 API 125 PyVISA Documentation Release 1 9 dev0 Return type int write_ascii_values message values converter u f separator u termination None encod ing None Write a string message to the device followed by values in ascii format The write_termination is always appended to it Parameters e message unicode Py2 or str Py3 the message to be sent e values data to be writen to the device e converter callable str function used to convert each value String formatting codes are also accepted Defaults to str e separator a callable that split the str into individual elements If a str is given data split separator is used Type separator collections Iterable T gt str str Returns number of bytes written Return type int write_binary values message values datatype u f
100. access_mode pyvisa constants AccessModes Specifies the mode by which the resource is to be accessed e open_timeout int Milliseconds before the open operation times out read_memory space offset width extended False Reads in an 8 bit 16 bit 32 bit or 64 bit value from the specified memory space and offset Parameters e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e width Number of bits to read e extended Use 64 bits offset independent of the platform Returns Data read from memory Corresponds to viln functions of the visa library register interface_type resource_class resource _class VI_ATTR_RSRC_CLASS specifies the resource class for example INSTR as defined by the canonical resource name 3 6 API 71 PyVISA Documentation Release 1 9 dev0 VISA Attribute VI_ATTR_RSRC_CLASS 3221159937 resource_info Get the extended information of this resource Parameters resource_name Unique symbolic name of a resource Return type pyvisa highlevel ResourceInfo resource_manufacturer_name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can
101. acks Parameters e session Unique logical identifier to a session e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be installed by a client appli cation e user_handle A value specified by an application that can be used for identifying handlers uniquely for an event type Returns user handle a ctypes object issue_warning_on None Set error codes on which to issue a warning set last_status Last return value of the library list_resources session query u INSTR Returns a tuple of all connected devices matching query Parameters query regular expression used to match devices lock session lock_type timeout requested_key None Establishes an access mode to the specified resources Corresponds to viLock function of the VISA library Parameters e session Unique logical identifier to a session 38 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 e lock_type Specifies the type of lock requested either Con stants EXCLUSIVE_LOCK or Constants SHARED LOCK e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error e requested_key This parameter is not used and should be set to VI LNULL when lockType is VI EXCLUSIVE_LOCK Returns access_key that can then be passed to other sessions to share the lock return value of the
102. ad the value e data value to be written to the bus Returns Data read from bus Returns return value of the library call Return type pyvisa constants StatusCode read session count Reads data from device or interface synchronously Corresponds to viRead function of the VISA library Parameters e session Unique logical identifier to a session e count Number of bytes to be read Returns data read return value of the library call Return type bytes pyvisa constants StatusCode read_asynchronousLy session count Reads data from device or interface asynchronously Corresponds to viReadAsync function of the VISA library Parameters e session Unique logical identifier to a session e count Number of bytes to be read Returns result jobid return value of the library call Return type ctypes buffer jobid ovvisa constants StatusCode read_memory session space offset width extended False Reads in an 8 bit 16 bit 32 bit or 64 bit value from the specified memory space and offset Corresponds to viln functions of the VISA library Parameters e session Unique logical identifier to a session e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e width Number of bits to read e extended Use 64 bits offset independent of the platform Returns Data read from memory return value of the library call Return type
103. alInstrument method 82 write pyvisa resources TCPIPInstrument method 91 write pyvisa resources TCPIPSocket method 98 write pyvisa resources USBInstrument method 107 write pyvisa resources USBRaw method 116 write_ascii_values pyvisa resources GPIBInstrument method 126 write_ascii_values pyvisa resources MessageBasedResource method 67 write_ascii_values method 83 write_ascii_values pyvisa resources TCPIPInstrument method 91 write_ascii_values method 98 write_ascii_values method 108 write_ascii_values method 116 write_asynchronously pyvisa highlevel VisaLibrary Base method 54 write_binary_values pyvisa resources GPIB Instrument method 126 write_binary_values pyvisa resources MessageBasedResource method 68 write_binary_values pyvisa resources SerialInstrument method 83 write_binary_values pyvisa resources TCPIPInstrument method 91 write_binary_values method 99 write_binary_values pyvisa resources USBInstrument method 108 write_binary_values method 116 write_from_file pyvisa highlevel VisaLibraryBase method 54 write_memory method 54 write_memory _ pyvisa resources FirewireInstrument method 138 write_memory method 145 write_memory pyvisa resources PXIMemory method 150 write_memory pyvisa resources RegisterBasedResource method 73 pyvisa constants StatusCode pyvisa resources Seria
104. all_handler unlock Relinquishes a lock for the specified resource values _format visa_attributes_classes lt class pyvisa attributes AttrVI_ATTR_RM_SESSION gt lt class pyvisa attributes At wait_on_event in_event_type timeout capture_timeout False Waits for an occurrence of the specified event in this resource Parameters e in_event_type Logical identifier of the event s to wait for e timeout Absolute time period in time units that the resource shall wait for a specified event to occur before returning the time elapsed error The time unit is in milliseconds None means waiting forever if necessary e capture_timeout When True will not produce a VisalOError VI_LERROR_TMO but instead return a WaitResponse with timed_out True 90 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 Returns A WaitResponse object that contains event_type context and ret value write message termination None encoding None Write a string message to the device The write_termination is always appended to it Parameters message unicode Py2 or str Py3 the message to be sent Returns number of bytes written Return type int write_ascii_values message values converter u f separator u termination None encod ing None Write a string message to the device followed by values in ascii format The write_termination is always appended to it Parameters e messag
105. alues pyvisa resources TCPIPInstrument method 91 write_values pyvisa resources TCPIPSocket method 99 write_values pyvisa resources USBInstrument method 108 write_values pyvisa resources USBRaw method 117 X xoff_char pyvisa resources SerialInstrument attribute 83 xon_char pyvisa resources SerialInstrument attribute 84 194 Index
106. and is issued you need to know which type datatype e g uint8 int8 single double etc is being used Py VISA use the same naming convention as the struct module You also need to know the endianness PyVISA assumes little endian as default If you have doubles d in big endian the call will be gt gt gt values inst query_binary_values CURV datatype d is_big_endian True You can also specify the output container type just as it was shown before 2 4 3 Writing ASCII values To upload a function shape to arbitrary wave generator the command might be WLISt WAVeform DATA lt waveform name gt lt function data gt where lt waveform name gt tells the device under which name to store the data gt gt gt values list range 100 gt gt gt inst write_ascii_values WLISt WAVeform DATA somename values Again you can specify the converter code gt gt gt inst write_ascii_values WLISt WAVeform DATA somename values converter x converter can be one of the Python string formatting codes But you can also specify a callable that takes a single argument if needed The default converter is The separator can also be specified just like in query_ascii_values gt gt gt inst write_ascii_values WLISt WAVeform DATA somename values converter x separator S You can provide a function to takes a iterable and returns an string Default value for the
107. andle a ctypes object interface_number VI_ATTR_INTF_NUM specifies the board number for the given interface VISA Attribute VI_ATTR_INTF_NUM 1073676662 Type int Range 0 lt value lt 65535 interface_type The interface type of the resource as a number last_status Last status code for this session Return type pyvisa constants StatusCode lock timeout u default requested_key None Establish a shared lock to the resource Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key Access key used by another session with which you want your ses sion to share a lock or None to generate a new shared access key Returns A new shared access key if requested_key is None otherwise same value as the re quested_key lock_context args kwds A context that locks Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key When using default of exclusive the lock is an exclusive lock Otherwise it is the access key for the shared lock or None to generate a new shared access key The returned context is the access_key if applicable lock_excl timeout u default Establish an exclusive lock to the resource Parameters timeout Abs
108. appropriate bus lines or the termination characters sequence was detected Attention Only the last character of the termination characters is really used to stop reading however the whole sequence is compared to the ending of the read string message If they don t match a warning is issued All line ending characters are stripped from the end of the string Return type str read_raw size None Read the unmodified string sent from the instrument to the computer In contrast to read no termination characters are stripped Return type bytes read_stb Service request status register read_termination Read termination character read_termination_context args kwds read_values fmt None container lt type list gt Read a list of floating point values from the device Parameters e fmt the format of the values If given it overrides the class attribute values_format Possible values are bitwise disjunctions of the above constants ascii single double and big_endian Default is ascii e container the output datatype Returns the list of read values 88 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 Return type list register interface_type resource_class resource_class VI_ATTR_RSRC_CLASS specifies the resource class for example INSTR as defined by the canonical resource name VISA Attribute VI_LATTR_RSRC_CLASS 3221159937 resource_info Get the exten
109. ast_status pyvisa resources Seriallnstrument attribute TI last_status pyvisa resources TCPIPInstrument attribute 86 last_status pyvisa resources TCPIPSocket attribute 93 last_status pyvisa resources USBInstrument attribute 102 last_status pyvisa resources USBRaw attribute 110 last_status pyvisa resources VXIBackplane attribute 164 pyvisa resources VXIInstrument attribute 153 last_status pyvisa resources VXIMemory attribute 158 LF pyvisa resources GPIBInstrument attribute 117 LF pyvisa resources MessageBasedResource attribute 61 LF pyvisa resources SerialInstrument attribute 74 LF pyvisa resources TCPIPInstrument attribute 84 LF pyvisa resources TCPIPSocket attribute 92 LF pyvisa resources USBInstrument attribute 99 LF pyvisa resources USBRaw attribute 109 LineState class in pyvisa constants 168 list_resources pyvisa highlevel ResourceManager method 55 list_resources method 38 list_resources_info pyvisa highlevel ResourceManager method 55 lock pyvisa highlevel VisaLibraryBase method 38 lock pyvisa resources FirewireInstrument method 135 lock pyvisa resources GPIBInstrument method 120 lock pyvisa resources GPIB Interface method 129 lockQ pyvisa resources MessageBasedResource method 63 lock pyvisa resources PXIInstrument method 141 lock pyvisa resources PXIMemory method 147 last_status attribute last_status
110. at does a minimum backend looks like Quite simple from pyvisa highlevel import VisaLibraryBase class MyLibrary VisaLibraryBase pass WRAPPER_CLASS MyLibrary Additionally you can provide a staticmethod named get_debug_info that should return a dictionary of debug infor mation which is printed when you call python m visa info An important aspect of developing a backend is knowing which VisaLibraryBase method to implement and what API to expose A complete implementation of a VISA Library requires a lot of functions basically almost all level 2 functions as described in Architecture there is also a complete list at the bottom of this page But a working implementation does not require all of them As a very minimum set you need e open_default_resource_manager returns a session to the Default Resource Manager resource e open Opens a session to the specified resource e close Closes the specified session event or find list e list_resources Returns a tuple of all connected devices matching query 14 Chapter 2 User guide PyVISA Documentation Release 1 9 dev0 you can get the signature below or here Visa Library But of course you cannot do anything interesting with just this In general you will also need e get_attribute Retrieves the state of an attribute e set_atribute Sets the state of an attribute If you need to start sending bytes to MessageBased instruments you will requir
111. at you also provide the log output To obtain it add the following lines to your code 3 3 Contributing to PyVISA 27 PyVISA Documentation Release 1 9 dev0 import visa visa log_to_screen 3 3 2 Contribute code To contribute fixes code or documentation to PyVISA send us a patch or fork PyVISA in github and submit the changes using a pull request You can also get the code from PyPI or GitHub You can either clone the public repository git clone git github com hgrecco pyvisa git Download the tarball curl OL https github com hgrecco pyvisa tarball master Or download the zipball curl OL https github com hgrecco pyvisa zipball master Once you have a copy of the source you can embed it in your Python package or install it into your site packages easily python setup py install Note If you have an old system installation of Python and you don t want to mess with it you can try Anaconda CE It is a free Python distribution by Continuum Analytics that includes many scientific packages 3 3 3 Contributing to an existing backend Backends are the central piece of PyVISA as they provide the low level communication over the different interfaces There a couple of backends in the wild which can use your help Look them up in PyPI try pyvisa in the search box and see where you can help 3 3 4 Contributing a new backend If you think ther
112. attribute 169 error_invalid_format attribute 169 error_invalid_handler_reference pyvisa constants StatusCode attribute 169 error_invalid_job_i_d pyvisa constants StatusCode at tribute 169 error_invalid_length attribute 169 error_invalid_line pyvisa constants StatusCode at tribute 169 error_invalid_lock_type pyvisa constants StatusCode at tribute 169 error_invalid_mask tribute 169 error_invalid_mechanism attribute 169 pyvisa constants StatusCode pyvisa constants StatusCode at pyvisa constants StatusCode pyvisa constants StatusCode pyvisa constants StatusCode pyvisa constants StatusCode pyvisa constants StatusCode pyvisa constants StatusCode at pyvisa constants StatusCode error_invalid_mode tribute 170 error_invalid_object attribute 170 error_invalid_offset pyvisa constants StatusCode at tribute 170 error_invalid_parameter pyvisa constants StatusCode at tribute 170 error_invalid_protocol pyvisa constants StatusCode at tribute 170 error_invalid_resource_name pyvisa constants StatusCode attribute 170 error_invalid_setup pyvisa constants StatusCode at tribute 170 error_invalid_size pyvisa constants StatusCode at tribute 170 error_invalid_width tribute 170 error_io pyvisa constants StatusCode attribute 170 error_library_not_found pyvisa constants StatusCode at tribute 170 error_line_in_use pyvisa constants StatusCode at tribu
113. atus code for this session Return type pyvisa constants StatusCode lock timeout u default requested_key None Establish a shared lock to the resource Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key Access key used by another session with which you want your ses sion to share a lock or None to generate a new shared access key Returns A new shared access key if requested_key is None otherwise same value as the re quested_key lock_context args kwds A context that locks Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key When using default of exclusive the lock is an exclusive lock Otherwise it is the access key for the shared lock or None to generate a new shared access key The returned context is the access_key if applicable lock_excl timeout u default Establish an exclusive lock to the resource Parameters timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout lock_state VIATTR_RSRC_LOCK_STATE indicates the current locking state of the resource The resource can be unlocked locked with an excl
114. brary path to my libvisa so 7 gt gt gt lib2 visa VisaLibrary path to my libvisa so 7 gt gt gt lib3 visa VisaLibrary path to my libvisa so 8 gt gt gt libl is 11b2 True gt gt gt libl is libs False Most of the time you will not need access toa VisaLibrary object but toa ResourceManager You can do gt gt gt lib visa VisaLibrary path to my libvisa so 7 gt gt gt rm lib resource_manager or equivalently gt gt gt rm visa ResourceManager path to my libvisa so 7 Note If the path for the library is not given the path is obtained from the user settings file if exists or guessed from the OS In 1 6 the state returned by the library is stored per resource Additionally warnings can be silenced by resource as well You can access with the last __status property All together these changes makes PyVISA thread safe VisaLibrary methods as way to call Visa functions In the original PyVISA implementation the VisaLibrary class was just having a reference to the ctypes library and a few functions In 1 5 we introduced a new VisaLibrary class pyvisa highlevel1 which has every single low level function defined in ct wrapper as bound methods In code this means that you can do gt gt gt import visa gt gt gt rm visa ResourceManager path to my libvisa so 7 gt gt gt lib rm visalib gt gt gt print lib read_stb session
115. brary call Return type jobid pyvisa constants StatusCode move_in session space offset length width extended False Moves a block of data to local memory from the specified address space and offset Corresponds to viMoveln functions of the VISA library Parameters e session Unique logical identifier to a session e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e length Number of elements to transfer where the data width of the elements to transfer is identical to the source data width e width Number of bits to read per element e extended Use 64 bits offset independent of the platform Returns Data read from the bus return value of the library call Return type list oyvisa constants StatusCode move_in_16 session space offset length extended False Moves an 16 bit block of data from the specified address space and offset to local memory Corresponds to viMovelIn16 functions of the VISA library Parameters e session Unique logical identifier to a session e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e length Number of elements to transfer where the data width of the elements to transfer is identical to the source data width e extended Use 64 bits offset independent of the platform Returns Data read from the b
116. c self session def in_8 self session space offset xtended False def in_16 self session space offset xtended False def in_32 self session space offset xtended False def in_64 self session space offset xtended False def install_handler self session event_type handler user_handle def list_resources self session query INSTR def lock self session lock_type timeout requested_key None def map_address self session map_space map_base map_size def gpib_pass_control self session primary_address secondary_address def move_out self session space offset length data width xtended False def map_trigger self session trigger_source trigger_destination mode def memory_allocation self session size extended False def memory_free self session offset xtended False def move self session source_space source_offset source_width destination_space def move_asynchronously self session source_space source_offset source_width def move_in_8 self session space offset length xtended False def move_in_16 self session space offset length xtended False def move_in_32 self session space offset length xtended False def move_in_64 self session space offset length xtended False def move_out_8 self session space offset length data xtended Fals Ja 2 7 A frontend for multiple backends 15 P
117. ce offset length data width extended False Moves a block of data from local memory to the specified address space and offset Parameters e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read length Number of elements to transfer where the data width of the elements to transfer is identical to the source data width data Data to write to bus width Number of bits to read per element extended Use 64 bits offset independent of the platform open access_mode lt AccessModes no_lock 0 gt open_timeout 5000 Opens a session to the specified resource Parameters access_mode pyvisa constants AccessModes Specifies the mode by which the resource is to be accessed e open_timeout int Milliseconds before the open operation times out 142 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 read_memory space offset width extended False Reads in an 8 bit 16 bit 32 bit or 64 bit value from the specified memory space and offset Parameters e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e width Number of bits to read e extended Use 64 bits offset independent of the platform Returns Data read from memory Corresponds to viln functions of the visa library register interface_type resourc
118. ce data width e data Data to write to bus e width Number of bits to read per element e extended Use 64 bits offset independent of the platform Returns return value of the library call Return type pyvisa constants StatusCode move_out_16 session space offset length data extended False Moves an 16 bit block of data from local memory to the specified address space and offset Corresponds to viMoveOut16 functions of the VISA library Parameters e session Unique logical identifier to a session e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e length Number of elements to transfer where the data width of the elements to transfer is identical to the source data width e data Data to write to bus e extended Use 64 bits offset independent of the platform Returns return value of the library call Return type pyvisa constants StatusCode move_out_32 session space offset length data extended False Moves an 32 bit block of data from local memory to the specified address space and offset Corresponds to viMoveOut32 functions of the VISA library Parameters e session Unique logical identifier to a session e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e length Number of elements to transfer where the data width
119. ce manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_NAME 3221159938 session Resource session handle Raises pyvisa errors InvalidSession if session is closed set_visa_attribute name state Sets the state of an attribute Parameters e name Attribute for which the state is to be modified Attributes e state The state of the attribute to be set for the specified object spec_version VIATTR_RSRC_SPEC_VERSION is the resource version that uniquely identifies the version of the VISA specification to which the implementation is compliant The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version The current VISA specification defines the value to be 00300000h VISA Attribute VI_LATTR_RSRC_SPEC_VERSION 1073676656 Type int Range 0 lt value lt 4294967295 timeout The timeout in milliseconds for all resource I O operations Special values immediate VI_TMO_IMMEDIATE 0 for convenience any value smaller than 1 is considered as 0 infinite VI_TMO_INFINITE float inf for convenience None is considered as float inf To set an infinite timeout you can also
120. cess this layer if you want to control certain specific aspects of the VISA library which are not implemented by the corresponding resource class All level 2 functions are bound methods of pyvisa highlevel VisaLibrary High level An object oriented layer for pyvisa highlevel ResourceManager and Pyvisa resources Resourc The ResourceManager implements methods to inspect connected resources You also use this object to open other resources instantiating the appropriate Resource derived classes 18 Chapter 2 User guide PyVISA Documentation Release 1 9 dev0 Resource and the derived classes implement functions and attributes access to the underlying resources in a Pythonic way Most of the time you will only need to instantiate a ResourceManager For a given resource you will use the pyvisa highlevel ResourceManager open_resource method to obtain the ap propriate object If needed you will be able to access the VisaLibrary object directly using the pyvisa highlevel ResourceManager visalib attribute The VisaLibrary does the low level calls In the default NI Backend levels 1 and 2 are implemented in the same package called pyvisa ctwrapper which stands for ctypes wrapper This package is included in PyVISA Other backends can be used just by passing the name of the backend to ResourceManager after the symbol See more information in A frontend for multiple backends 2 9 1 Calling middle an
121. context Not currently used leave as None get_visa_attribute name Retrieves the state of an attribute in this resource Parameters name Resource attribute for which the state query is made see Attributes Returns The state of the queried attribute for a specified resource Return type unicode Py2 or str Py3 list or other type ignore_warning warnings_constants Ignoring warnings context manager for the current resource Parameters warnings_constants constants identifying the warnings to ignore implementation_version VIATTR_RSRC_IMPL_VERSION is the resource version that uniquely identifies each of the dif ferent revisions or implementations of a resource This attribute value is defined by the individual manufacturer and increments with each new revision The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version VISA Attribute VI_ATTR_RSRC_IMPL_VERSION 1073676291 Type int Range 0 lt value lt 4294967295 install_handler event_type handler user_handle None Installs handlers for event callbacks in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be installed by a client appli cation e user_handle A value specified by an application that can be used for identifying handler
122. ctions that were present in vpp43 are now present in ctwrapper but they take an additional first parameter the foreign library wrapper We suggest that you replace vpp4 3 by accessing the VisaLibrary object under the attribute visalib of the resource manager which provides all foreign functions as bound methods see below No singleton objects The original PyVISA implementation relied on a singleton global objects for the library wrapper named visa_library an instance of the old pyvisa vpp43 VisaLibrary and the resource manager named resource_manager and instance of the old pyvisa visa ResourceManager These were instantiated 3 2 Migrating from PyVISA lt 1 5 25 PyVISA Documentation Release 1 9 dev0 on import and the user could rebind to a different library using the Lload_library method Calling this method however did not affect resource_manager and might lead to an inconsistent state There were additionally a few global structures such a status which stored the last status returned by the library and the warning context to prevent unwanted warnings In 1 5 there is a new VisaLibrary class and a new ResourceManager class they are both in pyvisa highlevel The new classes are not singletons at least not in the strict sense Multiple instances of VisaLibrary and ResourceManager are possible but only if they refer to different foreign libraries In code this means gt gt gt libl visa VisaLi
123. cturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes 3 6 API 105 PyVISA Documentation Release 1 9 dev0 Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_NAME 3221159938 send_end VIATTR_SEND_END_EN specifies whether to assert END during the transfer of the last byte of the buffer VISA Attribute VI_ATTR_SEND_END_EN 1073676310 Type bool serial_number VI_ATTR_USB_SERIAL_NUM specifies the USB serial number of this device VISA Attribute VI_ATTR_USB_SERIAL_NUM 3221160352 session Resource session handle Raises pyvisa errors InvalidSession if session is closed set_visa_attribute name state Sets the state of an attribute Parameters e name Attribute for which the state is to be modified Attributes e state The state of the attribute to be set for the specified object spec_version VIATTR_RSRC_SPEC_VERSION is the resource version that uniquely identifies the version of the VISA specification to which the implementation is compliant The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version The current VISA specification defines the
124. d low level functions After you have instantiated the ResourceManager gt gt gt import visa gt gt gt rm visa ResourceManager you can access the corresponding VisaLibrary instance under the visalib attribute As an example consider the VISA function viMapAddress It appears in the low level layer as the static method viMapAddress of visalib attributed and also appears in the middle level layer as map_address You can recognize low and middle level functions by their names Low level functions carry the same name as in the shared library and they are prefixed by vi Middle level functions have a friendlier more pythonic but still recognizable name Typically camelCase names where stripped from the leading vi and changed to underscore separated lower case names The docs about these methods is located here API Low level You can access the low level functions directly exposed as static methods for example gt gt gt rm visalib viMapAddress lt here goes the arguments gt To call this functions you need to know the function declaration and how to interface it to python To help you out the VisaLibrary object also contains middle level functions It is very likely that you will need to access the VISA constants using these methods You can find the information about these constants here api_constants Middle level The VisaLibrary object exposes the middle level functions which are one to one
125. d operations if None defaults to self query_delay Returns the answer from the device 78 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 Return type str query_ascii_values message converter u f separator u lay None Query the device for values in ascii format returning an iterable of values container lt type list gt de Parameters e message str the message to send e delay delay in seconds between write and read operations if None defaults to self query_delay e converter callable function used to convert each element Defaults to float e separator a callable that split the str into individual elements If a str is given data split separator is used e container container type to use for the output data Type separator str gt collections Iterable int str Returns the answer from the device Return type list query binary values message datatype u f is_big_endian False container lt type list gt de lay None header_fmt w ieee Converts an iterable of numbers into a block of data in the ieee format Parameters e message the message to send to the instrument e datatype the format string for a single element See struct module e is_big_endian boolean indicating endianess Defaults to False e container container type to use for the output data e delay delay in seconds between write and read operat
126. data Data to write to bus e width Number of bits to read e extended Use 64 bits offset independent of the platform Returns return value of the library call Return type pyvisa constants StatusCode 3 6 2 Resource Manager class pyvisa highlevel ResourcelInfo interface_type interface_board_number resource_class re source_name alias Resource extended information Named tuple with information about a resource Returned by some ResourceManager methods Interface_type Interface type of the given resource string pyvisa constants InterfaceType Interface_board_number Board number of the interface of the given resource string Resource_class Specifies the resource class for example INSTR of the given resource string Resource_name This is the expanded version of the given resource string The format should be similar to the VISA defined canonical resource name Alias Specifies the user defined alias for the given resource string class pyvisa highlevel ResourceManager VISA Resource Manager Parameters visa_library VisaLibrary Instance path of the VISA library or VisaLibrary spec string if not given the default for the platform will be used close Close the resource manager session last_status Last status code returned for an operation with this Resource Manager Return type pyvisa constants StatusCode list_resources query u INSTR Returns a tuple of all connected de
127. ddress space specified error_invalid_context None Specified event context is invalid error_invalid_degree None Specified degree is invalid error_invalid_event None Specified event type is not supported by the resource error_invalid_expression None Invalid expression specified for search error_invalid_format None A format specifier in the format string is invalid error_invalid_handler_reference None The specified handler reference is invalid error_invalid_job_i_d None Specified job identifier is invalid error_invalid_length None Invalid length specified error_invalid_line None The value specified by the line parameter is invalid error_invalid_lock_type None The specified type of lock is not supported by this resource error_invalid_mask None Invalid buffer mask specified 3 6 API 169 PyVISA Documentation Release 1 9 dev0 error_invalid_mechanism None Invalid mechanism specified error_invalid_mode None The specified mode is invalid error_invalid_object None The specified session or object reference is invalid error_invalid_offset None Invalid offset specified error_invalid_parameter None The value of an unknown parameter is invalid error_invalid_protocol None The protocol specified is invalid error_invalid_resource_name None Invalid resource reference specified Parsing error error_invalid_setup None Unable to start operation because s
128. ded information of this resource Parameters resource_name Unique symbolic name of a resource Return type pyvisa highlevel ResourceInfo resource_manufacturer_name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_MANF_NAME 3221160308 resource _ name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_NAME 3221159938 send_end VIATTR_SEND_END_EN specifies whether to assert END during the transfer of the last byte of the buffer VISA Attribute VI_ATTR_SEND_END_EN 1073676310 Type bool session Resource session handle Raises pyvisa errors InvalidSession if session is closed set_visa_attribute name state Sets the state of an attribute Parameters e name Attribute for which the state is to be modified Attributes e
129. delay delay in seconds between write and read operations if None defaults to self query_delay Returns the answer from the device Return type str query_ascii_values message converter u f separator u container lt type list gt de lay None Query the device for values in ascii format returning an iterable of values Parameters message str the message to send delay delay in seconds between write and read operations if None defaults to self query_delay converter callable function used to convert each element Defaults to float separator a callable that split the str into individual elements If a str is given data split separator is used container container type to use for the output data Type separator str gt collections Iterable int str 112 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 Returns the answer from the device Return type list query binary values message datatype u f is_big_endian False container lt type list gt de lay None header_fmt u ieee Converts an iterable of numbers into a block of data in the ieee format Parameters e message the message to send to the instrument e datatype the format string for a single element See struct module e is_big_endian boolean indicating endianess Defaults to False e container container type to use for the output data e delay delay
130. differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_MANF_NAME 3221160308 resource _ name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_NAME 3221159938 session Resource session handle Raises pyvisa errors InvalidSession if session is closed set_visa_attribute name state Sets the state of an attribute Parameters e name Attribute for which the state is to be modified Attributes e state The state of the attribute to be set for the specified object spec_version VIATTR_RSRC_SPEC_VERSION is the resource version that uniquely identifies the version of the VISA specification to which the implementation is compliant The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version The current VISA specification defines the value to be 00300000h VISA Attribute VI_LATTR_RSRC_SPEC_VERSION 1073676656 Type int Range 0 lt value lt 4294967295 72 Chapter 3 More information PyVISA Docume
131. ds data from device or interface through the use of a formatted I O read buffer Corresponds to viBufRead function of the VISA library Parameters e session Unique logical identifier to a session e count Number of bytes to be read Returns data read return value of the library call Return type bytes pyvisa constants StatusCode buffer write session data Writes data to a formatted I O write buffer synchronously Corresponds to viBufWrite function of the VISA library Parameters e session Unique logical identifier to a session e data bytes data to be written Returns number of written bytes return value of the library call Return type int opyvisa constants StatusCode clear session Clears a device Corresponds to viClear function of the VISA library Parameters session Unique logical identifier to a session Returns return value of the library call Return type pyvisa constants StatusCode 3 6 API 33 PyVISA Documentation Release 1 9 dev0 close session Closes the specified session event or find list Corresponds to viClose function of the VISA library Parameters session Unique logical identifier to a session event or find list Returns return value of the library call Return type pyvisa constants StatusCode disable_event session event_type mechanism Disables notification of the specified event type s via the specified mechanism s Corresponds to viDisableEvent functio
132. ds to viPeek32 function of the VISA library Parameters e session Unique logical identifier to a session e address Source address to read the value Returns Data read from bus return value of the library call Return type bytes pyvisa constants StatusCode peek_64 session address Read an 64 bit value from the specified address Corresponds to viPeek64 function of the VISA library Parameters e session Unique logical identifier to a session e address Source address to read the value Returns Data read from bus return value of the library call Return type bytes pyvisa constants StatusCode peek_ 8 session address Read an 8 bit value from the specified address Corresponds to viPeek8 function of the VISA library Parameters e session Unique logical identifier to a session e address Source address to read the value Returns Data read from bus return value of the library call Return type bytes pyvisa constants StatusCode poke session address width data Writes an 8 16 or 32 bit value from the specified address Corresponds to viPoke functions of the VISA library Parameters e session Unique logical identifier to a session 3 6 API 47 PyVISA Documentation Release 1 9 dev0 e address Source address to read the value e width Number of bits to read e data Data to be written to the bus Returns return value of the library call Return type pyvisa constants StatusC
133. e VIATTR_RSRC_LOCK_STATE indicates the current locking state of the resource The resource can be unlocked locked with an exclusive lock or locked with a shared lock VISA Attribute VI_LATTR_RSRC_LOCK_STATE 1073676292 Type class pyvisa constants AccessModes manufacturer_id VIL ATTR_ MANE ID is the manufacturer identification number of the device VISA Attribute VI_LATTR_MANF _ID 1073676505 3 6 API 141 PyVISA Documentation Release 1 9 dev0 Type int Range 0 lt value lt 65535 manufacturer_name This string attribute is the manufacturer name VISA Attribute VI_ATTR_MANF_NAME 3221160050 model_code VI_ATTR_MODEL_CODE specifies the model code for the device VISA Attribute VI_ATTR_MODEL_CODE 1073676511 Type int Range 0 lt value lt 65535 model_name This string attribute is the model name of the device VISA Attribute VI_ATTR_MODEL_NAME 3221160055 move_in space offset length width extended False Moves a block of data to local memory from the specified address space and offset Parameters e space Specifies the address space Constants SPACE offset Offset in bytes of the address or register from which to read length Number of elements to transfer where the data width of the elements to transfer is identical to the source data width width Number of bits to read per element e extended Use 64 bits offset independent of the platform move_out spa
134. e e is_big_endian boolean indicating endianess Returns number of bytes written Return type int write_raw message Write a byte message to the device Parameters message bytes the message to be sent Returns number of bytes written Return type int write termination Writer termination character write_values message values termination None encoding None class pyvisa resources USBInstrument args kwargs Communicates with devices of type USB manufacturer ID model code serial number More complex resource names can be specified with the following grammar USB board manufacturer ID model code serial number USB interface number INSTR Do not instantiate directly use pyvisa highlevel ResourceManager open_resource CR w r LF w n assert_trigger Sends a software trigger to the device before_close Called just before closing an instrument chunk_size 20480 clear Clears this resource close Closes the VISA session and marks the handle as invalid control_in request_type_bitmap_field request_id request_value index length 0 Performs a USB control pipe transfer from the device Parameters 3 6 API 99 PyVISA Documentation Release 1 9 dev0 request_type_bitmap_field bmRequestType parameter of the setup stage of a USB control transfer request_id bRequest parameter of the setup stage of a USB control transfer request_value
135. e e read Reads data from device or interface synchronously e write Writes data to device or interface synchronously For other usages or devices you might need to implement other functions Is really up to you and your needs These functions should raise a pyvisa errors VisalOError pyvisa errors VisalOWarning if necessary Complete list of level 2 functions to implement or emit a def read_memory self session space offset width xtended False def write_memory self session space offset data width xtended Fals def move_in self session space offset length width xtended False def peek self session address width def poke self session address width data def assert_interrupt_signal self session mode status_id def assert_trigger self session protocol def assert_utility_signal self session line def buffer_read self session count def buffer_write self session data def clear self session def close self session def disable_event self session event_type mechanism def discard_events self session vent_type mechanism def enable_event self session event_type mechanism context None def flush self session mask def get_attribute self session attribute def gpib_command self session data def gpib_control_atn self session mode def gpib_control_ren self session mode def gpib_send_if
136. e pyvisa resources PXIInstrument attribute 142 model_code pyvisa resources USBInstrument attribute 103 model_code pyvisa resources USBRaw attribute 112 model_code pyvisa resources V XIInstrument attribute 154 model_name pyvisa resources PXIInstrument attribute 142 model_name pyvisa resources USBInstrument attribute 103 model_name pyvisa resources USBRaw attribute 112 model_name pyvisa resources VXIInstrument attribute 154 move pyvisa highlevel VisaLibraryBase method 40 move_asynchronously pyvisa highlevel VisaLibrary Base method 40 move_in pyvisa highlevel VisaLibraryBase method 41 move_in pyvisa resources FirewireInstrument method 136 move_in pyvisa resources PXIInstrument method 142 move_in pyvisa resources PXIMemory method 147 move_in pyvisa resources RegisterBasedResource method 70 move_in pyvisa resources VXIMemory method 159 move_in_16 pyvisa highlevel VisaLibraryBase method 41 move_in_32 method 41 move_in_64 method 42 move_in_8 pyvisa highlevel VisaLibraryBase method 42 pyvisa resources USBRaw at pyvisa highlevel VisaLibrary Base pyvisa highlevel VisaLibrary Base attribute pyvisa highlevel VisaLibrary Base pyvisa highlevel VisaLibrary Base pyvisa highlevel VisaLibrary Base Index 185 PyVISA Documentation Release 1 9 dev0 move_out pyvisa highlevel VisaLibraryBase method
137. e unicode Py2 or str Py3 the message to be sent e values data to be writen to the device e converter callable str function used to convert each value String formatting codes are also accepted Defaults to str e separator a callable that split the str into individual elements If a str is given data split separator is used Type separator collections Iterable T gt str str Returns number of bytes written Return type int write_binary values message values datatype u f is_big_endian False termination None encoding None Write a string message to the device followed by values in binary format The write_termination is always appended to it Parameters e message unicode Py2 or str Py3 the message to be sent e values data to be writen to the device e datatype the format string for a single element See struct module e is_big_endian boolean indicating endianess Returns number of bytes written Return type int write_raw message Write a byte message to the device Parameters message bytes the message to be sent Returns number of bytes written Return type int write termination Writer termination character 3 6 API 91 PyVISA Documentation Release 1 9 dev0 write_values message values termination None encoding None class pyvisa resources TCPIPSocket args kwargs Communicates with to devices of type TCPIP host address port
138. e version and the lowest 8 bits as the sub minor number of the version The current VISA specification defines the value to be 00300000h VISA Attribute VI_LATTR_RSRC_SPEC_VERSION 1073676656 Type int Range 0 lt value lt 4294967295 timeout The timeout in milliseconds for all resource I O operations Special values immediate VI_TMO_IMMEDIATE 0 for convenience any value smaller than 1 is considered as 0 einfinite VI_TMO_INFINITE float inf for convenience None is considered as float inf To set an infinite timeout you can also use gt gt gt del instrument timeout uninstall_handler event_type handler user_handle None Uninstalls handlers for events in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be uninstalled by a client application e user_handle The user handle ctypes object or None returned by install_handler unlock Relinquishes a lock for the specified resource visa_attributes_classes lt class pyvisa attributes AttrVI_ATTR_RM_SESSION gt lt class pyvisa attributes At wait_on_event in_event_type timeout capture_timeout False Waits for an occurrence of the specified event in this resource Parameters e in_event_type Logical identifier of the event s to wait for e timeout Absolute time period in time units that the reso
139. e Attributes Returns The state of the queried attribute for a specified resource Return type unicode Py2 or str Py3 list or other type ignore_warning warnings_constants Ignoring warnings context manager for the current resource Parameters warnings_constants constants identifying the warnings to ignore implementation_version VIATTR_RSRC_IMPL_VERSION is the resource version that uniquely identifies each of the dif ferent revisions or implementations of a resource This attribute value is defined by the individual manufacturer and increments with each new revision The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version VISA Attribute VI_ATTR_RSRC_IMPL_VERSION 1073676291 Type int Range 0 lt value lt 4294967295 3 6 API 85 PyVISA Documentation Release 1 9 dev0 install_handler event_type handler user_handle None Installs handlers for event callbacks in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be installed by a client appli cation e user_handle A value specified by an application that can be used for identifying handlers uniquely for an event type Returns user handle a ctypes object interface_number VI_ATTR_INTF_NUM specifies the board nu
140. e accessing usr local vxipnp linux bin libvisa so 7 usr local vxipnp limux bin libvi First determine the details of your installation with the help of the following debug command python m visa info You will see the bitness of the Python interpreter and at the end you will see the list of VISA libraries that Py VISA was able to find The solution is to or 1 Install and use a VISA library matching your Python bitness Download and install it from National Instruments s VISA Run the debug command again to see if the new library was found by PyVISA If not create a configuration file as described in Configuring the NI backend If there is no VISA library with the correct bitness available try solution 2 Install and use a Python matching your VISA library bitness In Windows and Linux Download and install Python with the matching bitness Run your script again using the new Python In Mac OS X Python is usually delivered as universal binary 32 and 64 bits You can run it in 32 bit by running arch i386 python myscript py or in 64 bits by running arch x86_64 python myscript py You can create an alias by adding the following line alias python32 arch i386 python into your bashrc or profile or bash_profile or whatever file depending on which shell you are using You can also create a virtual environment for this 3 4 9 Where can I get m
141. e as a number last_status Last status code for this session Return type pyvisa constants StatusCode lock timeout u default requested_key None Establish a shared lock to the resource Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key Access key used by another session with which you want your ses sion to share a lock or None to generate a new shared access key Returns A new shared access key if requested_key is None otherwise same value as the re quested_key lock_context args kwds A context that locks Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key When using default of exclusive the lock is an exclusive lock Otherwise it is the access key for the shared lock or None to generate a new shared access key The returned context is the access_key if applicable lock_excl timeout u default Establish an exclusive lock to the resource Parameters timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout lock_state VIATTR_RSRC_LOCK_STATE indicates the current locking state of the resource The resource
142. e destination_space Specifies the address space of the destination e destination_offset Offset of the starting address or register to which to write e destination_width Specifies the data width of the destination e length Number of elements to transfer where the data width of the elements to transfer is identical to the source data width Returns return value of the library call Return type pyvisa constants StatusCode move_asynchronouslLy session source_space source_offset source_width destination_space des tination_offset destination_width length Moves a block of data asynchronously Corresponds to viMoveAsync function of the VISA library Parameters e session Unique logical identifier to a session e source_space Specifies the address space of the source e source_offset Offset of the starting address or register from which to read e source_width Specifies the data width of the source 40 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 e destination_space Specifies the address space of the destination e destination_offset Offset of the starting address or register to which to write e destination_width Specifies the data width of the destination e length Number of elements to transfer where the data width of the elements to transfer is identical to the source data width Returns Job identifier of this asynchronous move operation return value of the li
143. e element essentially treating the destination as a FIFO register VISA Attribute VI_ATTR_DEST_INCREMENT 1073676353 Type int Range 0 lt value lt 1 disable_event event_type mechanism Disables notification of the specified event type s via the specified mechanism s Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be disabled Con stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR VI_ALL_MECH 3 6 API 139 PyVISA Documentation Release 1 9 dev0 discard_events event_type mechanism Discards event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be dicarded Con stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR VI_ALL_MECH enable event event_type mechanism context None Enable event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be enabled Con stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR e context Not currently used leave as None get_visa_attribute name Retrieves the state of an attribute in this resource Parameters name Resource attribute for which the state query is made see Attributes Returns The state of the queried attribute for a specified resource
144. e event queue for the specified type has overflowed usually due to not closing previous events error_raw_read_protocol_violation None Violation of raw read protocol occurred during transfer error_raw_write_protocol_ violation None Violation of raw write protocol occurred during transfer error_resource_busy None The resource is valid but VISA cannot currently access it error_resource_locked None Specified type of lock cannot be obtained or specified operation cannot be performed because the resource is locked error_resource_not_found None Insufficient location information or the device or resource is not present in the system error_response_pending None A previous response is still pending causing a multiple query error 3 6 API 171 PyVISA Documentation Release 1 9 dev0 error_serial_framing None A framing error occurred during transfer error_serial_overrun None An overrun error occurred during transfer A character was not read from the hardware before the next character arrived error_serial_parity None A parity error occurred during transfer error_session_not_locked None The current session did not have any lock on the resource error_srq_not_occurred None Service request has not been received for the session error_system_error None Unknown system error error_timeout None Timeout expired before operation completed error_trigger_not_mapped None The path from t
145. e is a new way that low level communication can be achieved go for it You can use any of the existing backends as a template or start a thread in the issue tracker and we will be happy to help you 3 4 Frequently asked questions 3 4 1 Is PyVISA endorsed by National Instruments No PyVISA is developed independently of National Instrument as a wrapper for the VISA library 3 4 2 Who makes PyVISA PyVISA was originally programmed by Torsten Bronger and Gregor Thalhammer It is based on earlier experiences by Thalhammer 28 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 It was maintained from March 2012 to August 2013 by Florian Bauer It is currently maintained by Hernan E Grecco lt hernan grecco gmail com gt Take a look at AUTHORS for more information 3 4 3 Is PyVISA thread safe Yes PyVISA is thread safe starting from version 1 6 3 4 4 have an error in my program and I am having trouble to fix it PyVISA provides useful logs of all operations Add the following commands to your program and run it again import visa visa log_to_screen 3 4 5 found a bug how can report it Please report it on the Issue Tracker including operating system python version and library version In addition you might add supporting information by pasting the output of this command python m visa info 3 4 6 Error Image not found This error occurs when you have prov
146. e message and read Parameters e message str the message to send 94 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 e delay delay in seconds between write and read operations if None defaults to self query_delay Returns the answer from the device Return type str query _ascii_values message converter u f separator u container lt type list gt de lay None Query the device for values in ascii format returning an iterable of values Parameters e message str the message to send e delay delay in seconds between write and read operations if None defaults to self query_delay e converter callable function used to convert each element Defaults to float e separator a callable that split the str into individual elements If a str is given data split separator is used e container container type to use for the output data Type separator str gt collections Iterable int str Returns the answer from the device Return type list query binary values message datatype u f is_big_endian False container lt type list gt de lay None header_fmt w ieee Converts an iterable of numbers into a block of data in the ieee format Parameters e message the message to send to the instrument e datatype the format string for a single element See struct module e is_big_endian boolean indicating endianess Defaults to False
147. e of the REN line and optionally the device remote local state Constants GPIB_REN Returns return value of the library call 84 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 Return type VISAStatus disable_event event_type mechanism Disables notification of the specified event type s via the specified mechanism s Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be disabled stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR VI_ALL_MECH discard_events event_type mechanism Discards event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be dicarded stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR VI_ALL_MECH enable_event event_type mechanism context None Enable event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be enabled stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR e context Not currently used leave as None encoding Encoding used for read and write operations get_visa_attribute name Retrieves the state of an attribute in this resource Con Con Con Parameters name Resource attribute for which the state query is made se
148. e pyvisa constants StatusCode memory_allocation session size extended False Allocates memory from a resource s memory region Corresponds to viMemAlloc functions of the VISA library Parameters e session Unique logical identifier to a session 3 6 API 39 PyVISA Documentation Release 1 9 dev0 e size Specifies the size of the allocation e extended Use 64 bits offset independent of the platform Returns offset of the allocated memory return value of the library call Return type offset ovvisa constants StatusCode memory_free session offset extended False Frees memory previously allocated using the memory_allocation operation Corresponds to viMemFree function of the VISA library Parameters e session Unique logical identifier to a session e offset Offset of the memory to free e extended Use 64 bits offset independent of the platform Returns return value of the library call Return type pyvisa constants StatusCode move session source_space source_offset source_width destination_space destination_offset destina tion_width length Moves a block of data Corresponds to viMove function of the VISA library Parameters e session Unique logical identifier to a session e source_space Specifies the address space of the source e source_offset Offset of the starting address or register from which to read e source_width Specifies the data width of the source
149. e smaller than 1 is considered as 0 einfinite VI_TMO_INFINITE float inf for convenience None is considered as float inf To set an infinite timeout you can also use gt gt gt del instrument timeout uninstall_handler event_type handler user_handle None Uninstalls handlers for events in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be uninstalled by a client application e user_handle The user handle ctypes object or None returned by install_handler unlock Relinquishes a lock for the specified resource usb_protocol VI_ATTR_USB_PROTOCOL specifies the USB protocol used by this USB interface VISA Attribute VI_ATTR_USB_PROTOCOL 1073676711 Type int Range 0 lt value lt 255 3 6 API 115 PyVISA Documentation Release 1 9 dev0 values_format visa_attributes_classes lt class pyvisa attributes AttrVI_ATTR_RM_SESSION gt lt class pyvisa attributes At wait_on_event in_event_type timeout capture_timeout False Waits for an occurrence of the specified event in this resource Parameters e in_event_type Logical identifier of the event s to wait for e timeout Absolute time period in time units that the resource shall wait for a specified event to occur before returning the time elapsed error The time unit is in milliseconds None means waiting forever if
150. e_class resource class VI_ATTR_RSRC_CLASS specifies the resource class for example INSTR as defined by the canonical resource name VISA Attribute VI_ATTR_RSRC_CLASS 3221159937 resource_info Get the extended information of this resource Parameters resource_name Unique symbolic name of a resource Return type pyvisa highlevel ResourceInfo resource_manufacturer_name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_MANF_NAME 3221160308 resource_name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_LATTR_RSRC_NAME 3221159938 session Resource session handle Raises pyvisa errors InvalidSession if session is closed set_visa_attribute name state Sets the state of an attribute Parameters 3 6 API 143 PyVISA Documentation Relea
151. e_event pyvisa resources VXIBackplane method 163 disable_event method 151 disable_event pyvisa resources VXIMemory method 157 discard_events method 34 discard_events pyvisa resources FirewireInstrument method 134 discard_events pyvisa resources GPIBInstrument method 118 discard_events method 128 discard_events pyvisa resources MessageBasedResource method 61 discard_events method 139 discard_events pyvisa resources PXIMemory method 146 discard_events pyvisa resources RegisterBasedResource method 69 discard_events pyvisa resources Resource method 57 discard_events pyvisa resources SerialInstrument pyvisa resources TCPIPInstrument pyvisa resources USBInstrument pyvisa resources VXIInstrument pyvisa highlevel VisaLibrary Base pyvisa resources GPIBInterface pyvisa resources PXIInstrument method 75 discard_events pyvisa resources TCPIPInstrument method 85 discard_events pyvisa resources TCPIPSocket method 92 discard_events method 100 discard_events pyvisa resources USBRaw method 109 discard_events method 163 discard_events method 151 discard_events pyvisa resources VXIMemory method 157 discard_null pyvisa resources SerialInstrument tribute 75 pyvisa resources USBInstrument pyvisa resources VXIBackplane pyvisa resources VXIInstrument at E enable_event method 34 enable_event
152. ect that contains event_type context and ret value write_memory space offset data width extended False Write in an 8 bit 16 bit 32 bit value to the specified memory space and offset Parameters e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e data Data to write to bus e width Number of bits to read e extended Use 64 bits offset independent of the platform Corresponds to viOut functions of the visa library class pyvisa resources PXIMemory resource_manager resource_name Communicates with to devices of type PXI interface MEMACC Do not instantiate directly use pyvisa highlevel ResourceManager open_resource before_close Called just before closing an instrument clear Clears this resource close Closes the VISA session and marks the handle as invalid destination_increment VI ATTR_DEST_INCREMENT is used in the viMoveOutXX operations to specify by how many elements the destination offset is to be incremented after every transfer The default value of this attribute is 1 that is the destination address will be incremented by 1 after each transfer and the viMoveOutXX operations move into consecutive elements If this attribute is set to 0 the viMove OutXX operations will always write to the same element essentially treating the destination as a FIFO register VISA Attribute VI_ATTR_DE
153. egister read_termination Read termination character read_termination_context args kwds read_values fmt None container lt type list gt Read a list of floating point values from the device Parameters e fmt the format of the values If given it overrides the class attribute values_format Possible values are bitwise disjunctions of the above constants ascii single double and big_endian Default is ascii e container the output datatype Returns the list of read values Return type list register interface_type resource_class resource _class VI_ATTR_RSRC_CLASS specifies the resource class for example INSTR as defined by the canonical resource name VISA Attribute VI_ATTR_RSRC_CLASS 3221159937 resource_info Get the extended information of this resource Parameters resource_name Unique symbolic name of a resource Return type pyvisa highlevel ResourceInfo resource_manufacturer_name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_MANF_NAME 3221160308 resource_name VI ATTR_RSRC_MANF_NAME is a string that corresponds to the manufa
154. eout pyvisa resources Resource attribute 60 timeout pyvisa resources SerialInstrument attribute 82 timeout pyvisa resources TCPIPInstrument attribute 90 timeout pyvisa resources TCPIPSocket attribute 97 timeout pyvisa resources USBInstrument attribute 106 timeout pyvisa resources USBRaw attribute 115 timeout pyvisa resources VXIBackplane attribute 166 timeout pyvisa resources V XIInstrument attribute 156 timeout pyvisa resources VXIMemory attribute 161 U uninstall_all_visa_handlers pyvisa highlevel VisaLibraryBase method 51 uninstall_handler pyvisa highlevel VisaLibraryBase method 51 uninstall_handler pyvisa resources FirewireInstrument method 138 uninstall_handler pyvisa resources GPIBInstrument method 125 uninstall_handler method 133 uninstall_handler pyvisa resources MessageBasedResource method 67 uninstall_handler method 144 uninstall_handler method 150 uninstall_handler pyvisa resources RegisterBasedResource method 73 pyvisa resources GPIBInterface pyvisa resources PXI Instrument pyvisa resources PXIMemory Index 191 PyVISA Documentation Release 1 9 dev0 uninstall_handler pyvisa resources Resource method 61 uninstall_handler method 82 uninstall_handler pyvisa resources TCPIPInstrument method 90 uninstall_handler method 97 uninstall_handler method 107 uninstall_handler pyvisa res
155. ery transfer The default value of this attribute is 1 that is the destination address will be incremented by 1 after each transfer and the viMoveOutXX operations move into consecutive elements If this attribute is set to 0 the viMove OutXX operations will always write to the same element essentially treating the destination as a FIFO register VISA Attribute VI_ATTR_DEST_INCREMENT 1073676353 Type int Range 0 lt value lt 1 disable_event event_type mechanism Disables notification of the specified event type s via the specified mechanism s Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be disabled Con stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR VI_ALL_MECH discard_events event_type mechanism Discards event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be dicarded Con stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR VI_ALL_MECH 3 6 API 157 PyVISA Documentation Release 1 9 dev0 enable_event event_type mechanism context None Enable event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be enabled Con stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR e
156. es the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e data Data to write to bus e extended Use 64 bits offset independent of the platform Returns return value of the library call Return type pyvisa constants StatusCode 3 6 API 45 PyVISA Documentation Release 1 9 dev0 out_8 session space offset data extended False Write in an 8 bit value from the specified memory space and offset Corresponds to viOut8 functions of the VISA library Parameters e session Unique logical identifier to a session e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e data Data to write to bus e extended Use 64 bits offset independent of the platform Returns return value of the library call Return type pyvisa constants StatusCode parse_resource session resource_name Parse a resource string to get the interface information Corresponds to viParseRsrc function of the VISA library Parameters e session Resource Manager session should always be the Default Resource Manager for VISA returned from open_default_resource_manager e resource_name Unique symbolic name of a resource Returns Resource information with interface type and board number return value of the library call Return type pyvisa highlevel ResourceInfo pyvisa constants Statu
157. esources SerialInstrument 80 attribute resource_manufacturer_name pyvisa resources TCPIPInstrument attribute 89 resource_manufacturer_name pyvisa resources TCPIPSocket attribute 96 resource_manufacturer_name pyvisa resources USBInstrument attribute 105 resource_manufacturer_name pyvisa resources USBRaw attribute 114 resource_manufacturer_name pyvisa resources VXIBackplane 165 resource_manufacturer_name pyvisa resources V XIInstrument 155 resource_manufacturer_name pyvisa resources VXIMemory 160 resource_name pyvisa resources FirewireInstrument at tribute 137 resource_name pyvisa resources GPIB Instrument attribute 123 resource_name pyvisa resources GPIBInterface at tribute 131 resource_name pyvisa resources MessageBasedResource attribute 66 resource_name pyvisa resources PXIInstrument at tribute 143 resource_name pyvisa resources PXIMemory attribute 149 resource_name pyvisa resources RegisterBasedResource attribute 72 resource_name pyvisa resources Resoutce attribute 60 resource_name pyvisa resources SerialInstrument attribute 81 resource_name pyvisa resources TCPIPInstrument at tribute 89 resource_name pyvisa resources TCPIPSocket attribute 97 resource_name pyvisa resources USBInstrument at tribute 105 resource_name pyvisa resources USBRaw 114 resource_name pyvisa resources VXIBackplane at tribute 165 resource_name pyvisa re
158. esources MessageBasedResource method 65 read pyvisa resources SerialInstrument method 79 read pyvisa resources TCPIPInstrument method 88 read pyvisa resources TCPIPSocket method 95 read pyvisa resources USBInstrument method 104 read pyvisa resources USBRaw method 113 read_asynchronously pyvisa highlevel VisaLibrary Base method 49 read_memory method 49 pyvisa resources FirewireInstrument method 136 read_memory method 142 read_memory pyvisa resources PXIMemory method 148 read_memory pyvisa resources RegisterBasedResource method 71 read_memory pyvisa resources VXIMemory method 160 read_raw pyvisa resources GPIBInstrument method 122 read_raw pyvisa resources MessageBasedResource method 65 read_raw pyvisa resources SerialInstrument method 80 read_raw pyvisa resources TCPIPInstrument method 88 read_raw pyvisa resources TCPIPSocket method 96 read_raw pyvisa resources USBInstrument method 104 read_raw pyvisa resources USBRaw method 113 read_stb pyvisa highlevel VisaLibraryBase method 49 read_stb pyvisa resources GPIBInstrument method 122 read_stb pyvisa resources MessageBasedResource method 65 read_stb pyvisa resources Seriallnstrument method 80 read_stb pyvisa resources TCPIPInstrument method 88 read_stb pyvisa resources TCPIPSocket method 96 read_stb pyvisa resources USBInstrument method
159. essage unicode Py2 or str Py3 the message to be sent e values data to be writen to the device e datatype the format string for a single element See struct module 116 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 e is_big_endian boolean indicating endianess Returns number of bytes written Return type int write_raw message Write a byte message to the device Parameters message bytes the message to be sent Returns number of bytes written Return type int write termination Writer termination character write_values message values termination None encoding None class pyvisa resources GPIBInstrument args kwargs Communicates with to devices of type GPIB lt primary address gt INSTR More complex resource names can be specified with the following grammar GPIB board primary address secondary address INSTR Do not instantiate directly use pyvisa highlevel ResourceManager open_resource CR w r LF w n allow_dma This attribute specifies whether I O accesses should use DMA VI_TRUE or Programmed I O VI_FALSE In some implementations this attribute may have global effects even though it is documented to be a local attribute Since this affects performance and not functionality that behavior is acceptable VISA Attribute VI_LATTR_DMA_ALLOW_EN 1073676318 Type bool assert_trigger Sends a software trigger to the device
160. ession pyvisa resources FirewireInstrument attribute 137 session pyvisa resources GPIBInstrument attribute 124 session pyvisa resources GPIB Interface attribute 132 session pyvisa resources MessageBasedResource at tribute 66 session pyvisa resources PXIInstrument attribute 143 session pyvisa resources PXIMemory attribute 149 session pyvisa resources RegisterBasedResource at tribute 72 session pyvisa resources Resource attribute 60 session pyvisa resources Seriallnstrument attribute 8 1 session pyvisa resources TCPIPInstrument attribute 89 session pyvisa resources TCPIPSocket attribute 97 session pyvisa resources USBInstrument attribute 106 session pyvisa resources USBRaw attribute 114 session pyvisa resources VXIBackplane attribute 166 session pyvisa resources VXIInstrument attribute 155 session pyvisa resources VXIMemory attribute 161 set_attribute pyvisa highlevel VisaLibrary Base method 50 set_buffer pyvisa highlevel VisaLibraryBase method 50 set_visa_attribute pyvisa resources FirewireInstrument method 137 set_visa_attribute pyvisa resources GPIB Instrument method 124 set_visa_attribute method 132 pyvisa resources GPIBInterface set_visa_attribute pyvisa resources MessageBasedResource method 66 set_visa_attribute method 143 set_visa_attribute method 149 pyvisa resources PXIInstrument pyvisa resources PXIMemory set_visa_attr
161. etup is invalid due to inconsistent state of properties error_invalid_size None Invalid size of window specified error_invalid_width None Invalid source or destination width specified error_io None Could not perform operation because of I O error error_library_not_found None A code library required by VISA could not be located or loaded error_line_in_use None The specified trigger line is currently in use error_machine_not_available None The remote machine does not exist or is not accepting any connections error_memory_not_shared None The device does not export any memory error_no_listeners None No listeners condition is detected both NRFD and NDAC are deasserted error_no_permission None Access to the remote machine is denied error_nonimplemented_operation None The specified operation is unimplemented error_nonsupported_attribute None The specified attribute is not defined or supported by the referenced session event or find list error_nonsupported_attribute_state None The specified state of the attribute is not valid or is not supported as defined by the session event or find list error_nonsupported_format None A format specifier in the format string is not supported 170 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 error_nonsupported_interrupt None The interface cannot generate an interrupt on the requested level or with the requested stat
162. event occurrence of the requested type s available for this session 172 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 success_syncronous None Asynchronous operation request was performed synchronously success_termination_character_read None The specified termination character was read success_trigger_already_mapped None The path from the trigger source line trigSrc to the destination line trigDest is already mapped warning _configuration_not_loaded None The specified configuration either does not exist or could not be loaded The VISA specified defaults are used warning ext_function_not_implemented None The operation succeeded but a lower level driver did not implement the extended functionality warning _nonsupported_attribute_state None Although the specified state of the attribute is valid it is not supported by this resource implementation warning _nonsupported_buffer None The specified buffer is not supported warning _null_object None The specified object reference is uninitialized warning queue_overflow None VISA received more event information of the specified type than the configured queue size could hold warning _unknown_status None The status code passed to the operation could not be interpreted 3 6 API 173 PyVISA Documentation Release 1 9 dev0 174 Chapter 3 More information Python Module Index p pyvisa constants 167
163. f a str is given data split separator is used Type separator collections Iterable T gt str str Returns number of bytes written Return type int write_binary values message values datatype u f is_big_endian False termination None encoding None Write a string message to the device followed by values in binary format The write_termination is always appended to it Parameters e message unicode Py2 or str Py3 the message to be sent e values data to be writen to the device e datatype the format string for a single element See struct module e is_big_endian boolean indicating endianess Returns number of bytes written Return type int write_raw message Write a byte message to the device Parameters message bytes the message to be sent Returns number of bytes written Return type int write termination Writer termination character write_values message values termination None encoding None xoff_char VIATTR_ASRL_XOFF_CHAR specifies the value of the XOFF character used for XON XOFF flow control both directions If XON XOFF flow control software handshaking is not being used the value of this attribute is ignored VISA Attribute VI_LATTR_ASRL_XOFF_CHAR 1073676482 3 6 API 83 PyVISA Documentation Release 1 9 dev0 Type int Range 0 lt value lt 255 xon_char VI_ATTR_ASRL_XON_CHAR specifies the value of the XON character used for XON XOFF flow
164. f the version and the lowest 8 bits as the sub minor number of the version VISA Attribute VI_ATTR_RSRC_IMPL_VERSION 1073676291 Type int Range 0 lt value lt 4294967295 install_handler event_type handler user_handle None Installs handlers for event callbacks in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be installed by a client appli cation e user_handle A value specified by an application that can be used for identifying handlers uniquely for an event type Returns user handle a ctypes object interface_number VI_ATTR_INTF_NUM specifies the board number for the given interface VISA Attribute VI_ATTR_INTF_NUM 1073676662 Type int Range 0 lt value lt 65535 interface_type The interface type of the resource as a number io_protocol VI_ATTR_IO_PROT specifies which protocol to use In VXI you can choose normal word serial or fast data channel FDC In GPIB you can choose normal or high speed HS 488 transfers In serial TCPIP or USB RAW you can choose normal transfers or 488 2 defined strings In USB INSTR you can choose normal or vendor specific transfers VISA Attribute VI_ATTR_IO_PROT 1073676316 Type int 3 6 API 101 PyVISA Documentation Release 1 9 dev0 Range 0 lt value lt 65535 is_4882_ compliant VI ATTR_4882_COMPLIANT specifies whether the device is 488 2 compliant VISA A
165. f this attribute is 1 that is the source address will be incremented by after each transfer and the viMoveInXX operations move from consecutive elements If this attribute is set to 0 the viMoveInXX operations will always read from the same element essentially treating the source as a FIFO register VISA Attribute VI_ATTR_SRC_INCREMENT 1073676352 Type int Range 0 lt value lt 1 spec_version VI_ATTR_RSRC_SPEC_VERSION is the resource version that uniquely identifies the version of the VISA specification to which the implementation is compliant The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version The current VISA specification defines the value to be 00300000h VISA Attribute VI_LATTR_RSRC_SPEC_VERSION 1073676656 Type int Range 0 lt value lt 4294967295 3 6 API 161 PyVISA Documentation Release 1 9 dev0 timeout The timeout in milliseconds for all resource I O operations Special values immediate VI_TMO_IMMEDTATE 0 for convenience any value smaller than 1 is considered as 0 infinite VI_TMO_INFINITE float inf for convenience None is considered as float inf To set an infinite timeout you can also use gt gt gt del instrument timeout uninstall_handler event_type handler use
166. facturer_name VIATTR_RSRC_MANF_ NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes 160 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_MANF_NAME 3221160308 resource _ name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_NAME 3221159938 session Resource session handle Raises pyvisa errors InvalidSession if session is closed set_visa_attribute name state Sets the state of an attribute Parameters e name Attribute for which the state is to be modified Attributes e state The state of the attribute to be set for the specified object source_increment VIL ATTR_SRC_INCREMENT is used in the viMoveInXX operations to specify by how many ele ments the source offset is to be incremented after every transfer The default value o
167. ffset independent of the platform move_out space offset length data width extended False Moves a block of data from local memory to the specified address space and offset Parameters e space Specifies the address space Constants SPACE offset Offset in bytes of the address or register from which to read length Number of elements to transfer where the data width of the elements to transfer is identical to the source data width data Data to write to bus width Number of bits to read per element extended Use 64 bits offset independent of the platform open access_mode lt AccessModes no_lock 0 gt open_timeout 5000 Opens a session to the specified resource Parameters access_mode pyvisa constants AccessModes Specifies the mode by which the resource is to be accessed e open_timeout int Milliseconds before the open operation times out read_memory space offset width extended False Reads in an 8 bit 16 bit 32 bit or 64 bit value from the specified memory space and offset Parameters e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read width Number of bits to read 136 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 e extended Use 64 bits offset independent of the platform Returns Data read from memory Corresponds to viln functi
168. g session before returning an error Defaults to self timeout 86 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 lock_state VIATTR_RSRC_LOCK_STATE indicates the current locking state of the resource The resource can be unlocked locked with an exclusive lock or locked with a shared lock VISA Attribute VI_LATTR_RSRC_LOCK_STATE 1073676292 Type class pyvisa constants AccessModes open access_mode lt AccessModes no_lock 0 gt open_timeout 5000 Opens a session to the specified resource Parameters access_mode pyvisa constants AccessModes Specifies the mode by which the resource is to be accessed e open_timeout int Milliseconds before the open operation times out query message delay None A combination of write message and read Parameters e message str the message to send e delay delay in seconds between write and read operations if None defaults to self query_delay Returns the answer from the device Return type str query_ascii_values message converter u f separator u container lt type list gt de lay None Query the device for values in ascii format returning an iterable of values Parameters e message str the message to send e delay delay in seconds between write and read operations if None defaults to self query_delay e converter callable function used to convert each element Defaults to float e se
169. gs_constants constants identifying the warnings to ignore implementation_version VIATTR_RSRC_IMPL_VERSION is the resource version that uniquely identifies each of the dif ferent revisions or implementations of a resource This attribute value is defined by the individual manufacturer and increments with each new revision The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version VISA Attribute VI_ATTR_RSRC_IMPL_VERSION 1073676291 Type int Range 0 lt value lt 4294967295 install_handler event_type handler user_handle None Installs handlers for event callbacks in this resource Parameters e event_type Logical event identifier 128 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 e handler Interpreted as a valid reference to a handler to be installed by a client appli cation e user_handle A value specified by an application that can be used for identifying handlers uniquely for an event type Returns user handle a ctypes object interface_number VI_ATTR_INTF_NUM specifies the board number for the given interface VISA Attribute VI_ATTR_INTF_NUM 1073676662 Type int Range 0 lt value lt 65535 interface_type The interface type of the resource as a number io_protocol VI_ATTR_IO_PROT specifies which protocol to use In
170. gt keithley assert_trigger gt gt gt keithley wait_for_srq With sending the service request the instrument tells us that the measurement has been finished and that the results are ready for transmission We could read them with keithley query trace data however then we d get 000 0004E 0 000 0005E 0 000 0004E 0 000 0007E 0 000 0000E 0 000 0007E 0 000 0008E 0 000 0004E 0 000 0002E 0 000 0005E 0 which we would have to convert to a Python list of numbers Fortunately the guery_ascii_values method does this work for us gt gt gt voltages keithley query_ascii_values trace data gt gt gt print Average voltage sum voltages len voltages Finally we should reset the instrument s data buffer and SRQ status register so that it s ready for a new run Again this is explained in detail in the instrument s manual gt gt gt keithley query status measurement gt gt gt keithley write trace clear feed control next That s it 18 lines of lucid code Well SCPI is awkward but that s another story 2 6 Resources A resource represents an instrument e g a measurement device There are multiple classes derived from resources representing the different available types of resources eg GPIB Serial Each contains the particular set of attributes an methods that are available by the underlying device You
171. he VISA library Parameters e session Unique logical identifier to a session e data bytes data tor write Returns Number of written bytes return value of the library call Return type int opyvisa constants StatusCode gpib_control_atn session mode Specifies the state of the ATN line and the local active controller state Corresponds to viGpibControlATN function of the VISA library Parameters e session Unique logical identifier to a session 3 6 API 35 PyVISA Documentation Release 1 9 dev0 e mode Specifies the state of the ATN line and optionally the local active controller state Constants VI_GPIB_ATN Returns return value of the library call Return type pyvisa constants StatusCode gpib_control_ren session mode Controls the state of the GPIB Remote Enable REN interface line and optionally the remote local state of the device Corresponds to viGpibControlREN function of the VISA library Parameters e session Unique logical identifier to a session e mode Specifies the state of the REN line and optionally the device remote local state Constants VI_GPIB_REN Returns return value of the library call Return type pyvisa constants StatusCode gpib_pass_control session primary_address secondary _address Tell the GPIB device at the specified address to become controller in charge CIC Corresponds to viGpibPassControl function of the VISA library Parameters e session
172. he trigger source line trigSrc to the destination line trigDest is not currently mapped error_user_buffer None A specified user buffer is not valid or cannot be accessed for the required size error_window_already_mapped None The specified session currently contains a mapped window error_window_not_mapped None The specified session is currently unmapped success None Operation completed successfully success_device_not_present None Session opened successfully but the device at the specified address is not responding success_event_already_disabled None Specified event is already disabled for at least one of the specified mechanisms success_event_already_enabled None Specified event is already enabled for at least one of the specified mechanisms success_max_count_read None The number of bytes read is equal to the input count success_nested_exclusive None Operation completed successfully and this session has nested exclusive locks success_nested_shared None Operation completed successfully and this session has nested shared locks success_no_more_handler_calls_in_chain None Event handled successfully Do not invoke any other handlers on this session for this event success_queue_already_empty None Operation completed successfully but the queue was already empty success_queue_not_empty None Wait terminated successfully on receipt of an event notification There is still at least one more
173. ibute pyvisa resources RegisterBasedResource method 72 set_visa_attribute pyvisa resources Resource method 60 set_visa_attribute method 81 set_visa_attribute pyvisa resources TCPIPInstrument method 89 set_visa_attribute method 97 set_visa_attribute method 106 set_visa_attribute pyvisa resources USBRaw method 114 set_visa_attribute method 166 set_visa_attribute method 155 set_visa_attribute method 161 shared_lock pyvisa constants AccessModes attribute 167 source_increment pyvisa resources PXIInstrument at tribute 144 source_increment pyvisa resources PXIMemory at tribute 149 source_increment pyvisa resources VXIInstrument at tribute 155 source_increment pyvisa resources VXIMemory at tribute 161 spec_version pyvisa resources FirewireInstrument attribute 137 spec_version pyvisa resources GPIBInstrument at tribute 124 spec_version pyvisa resources GPIBInterface attribute 132 spec_version pyvisa resources MessageBasedResource attribute 66 spec_version pyvisa resources PXIInstrument attribute 144 pyvisa resources SerialInstrument pyvisa resources TCPIPSocket pyvisa resources USBInstrument pyvisa resources VXIBackplane pyvisa resources VXIInstrument pyvisa resources V XIMemory 190 Index PyVISA Documentation Release 1 9 dev0 spec_version pyvisa resources PXIMemory attribute 149 spec_version pyvis
174. ided an invalid path for the VISA library Check that the path provided to the constructor or in the configuration file 3 4 7 Error Could not found VISA library This error occurs when you have not provided a path for the VISA library and PyVISA is not able to find it for you You can solve it by providing the library path to the VisaLibrary or ResourceManager constructor gt gt gt visalib VisaLibrary path to library or gt gt gt rm ResourceManager Path to library or creating a configuration file as described in Configuring the NI backend 3 4 8 Error No matching architecture This error occurs when you the Python architecture does not match the VISA architecture Note PyVISA tries to parse the error from the underlying foreign function library to provide a more useful error message If it does not succeed it shows the original one In Mac OS X the original error message looks like this 3 4 Frequently asked questions 29 PyVISA Documentation Release 1 9 dev0 OS Error dlopen Library Frameworks visa framework visa 6 no suitable image found Did find Library Frameworks visa framework visa no matching architecture in universal wrapper Library Frameworks visa framework visa no matching architecture in universal wrapper In Linux the original error message looks like this OS Error Could not open VISA library Error whil
175. implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_NAME 3221159938 session Resource session handle Raises pyvisa errors InvalidSession if session is closed set_visa_attribute name state Sets the state of an attribute Parameters e name Attribute for which the state is to be modified Attributes e state The state of the attribute to be set for the specified object spec_version VIATTR_RSRC_SPEC_VERSION is the resource version that uniquely identifies the version of the VISA specification to which the implementation is compliant The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version The current VISA specification defines the value to be 00300000h VISA Attribute VILATTR_RSRC_SPEC_VERSION 1073676656 Type int Range 0 lt value lt 4294967295 stb Service request status register timeout The timeout in milliseconds for all resource I O operations Special values immediate VI_TMO_IMMEDIATE 0 for convenience any value smaller than 1 is considered as 0 einfinite VI_TMO_INFINITE float
176. in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key When using default of exclusive the lock is an exclusive lock Otherwise it is the access key for the shared lock or None to generate a new shared access key The returned context is the access_key if applicable lock_excl timeout u default Establish an exclusive lock to the resource 3 6 API 135 PyVISA Documentation Release 1 9 dev0 Parameters timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout lock_state VIATTR_RSRC_LOCK_STATE indicates the current locking state of the resource The resource can be unlocked locked with an exclusive lock or locked with a shared lock VISA Attribute VI_LATTR_RSRC_LOCK_STATE 1073676292 Type class pyvisa constants AccessModes move_in space offset length width extended False Moves a block of data to local memory from the specified address space and offset Parameters e space Specifies the address space Constants SPACE offset Offset in bytes of the address or register from which to read length Number of elements to transfer where the data width of the elements to transfer is identical to the source data width width Number of bits to read per element extended Use 64 bits o
177. in particular for GPIB For RS2372 it s awa You can specify the character to add to each outgoing message using the write_termination attribute query_delay and send_end There are two further options related to message termination namely send_end and query_delay send_end is a boolean If it s True the default the EOI line is asserted after each write operation signalling the end of the operation EOI is GPIB specific but similar action is taken for other interfaces The argument query_delay is the time in seconds to wait after each write operation So you could write my_instrument rm open_resource GPIB 10 send_end False delay 1 2 This will set the delay to 1 2 seconds and the EOI line is omitted By the way omitting EOI is not recommended so if you omit it nevertheless you should know what you re doing 2 7 A frontend for multiple backends A small historical note might help to make this section clearer So bear with with me for a couple of lines Originally PyVISA was a Python wrapper to the VISA library More specifically it was ct ypes wrapper around the NI VISA This approach worked fine but made it difficult to develop other ways to communicate with instruments in platforms where NI VISA was not available Users had to change their programs to use other packages with different API Since 1 6 PyVISA is a frontend to VISA It provides a nice Pythonic API and can connect to multiple backends
178. ing None Read a string from the device Reading stops when the device stops sending e g by setting appropriate bus lines or the termination characters sequence was detected Attention Only the last character of the termination characters is really used to stop reading however the whole sequence is compared to the ending of the read string message If they don t match a warning is issued All line ending characters are stripped from the end of the string Return type str read_raw size None Read the unmodified string sent from the instrument to the computer In contrast to read no termination characters are stripped Return type bytes read_stb Service request status register read_termination Read termination character read_termination_context args kwds read_values fmt None container lt type list gt Read a list of floating point values from the device Parameters e fmt the format of the values If given it overrides the class attribute values_format Possible values are bitwise disjunctions of the above constants ascii single double and big_endian Default is ascii e container the output datatype Returns the list of read values Return type list register interface_type resource_class resource _class VI_ATTR_RSRC_CLASS specifies the resource class for example INSTR as defined by the canonical resource name VISA Attribute VI_ATTR_RSRC_CLASS 3221159937
179. int pyvisa constants StatusCode read_stb session Reads a status byte of the service request Corresponds to viReadSTB function of the VISA library Parameters session Unique logical identifier to a session Returns Service request status byte return value of the library call 3 6 API 49 PyVISA Documentation Release 1 9 dev0 Return type int pyvisa constants StatusCode read_to_file session filename count Read data synchronously and store the transferred data in a file Corresponds to viReadToFile function of the VISA library Parameters e session Unique logical identifier to a session e filename Name of file to which data will be written e count Number of bytes to be read Returns Number of bytes actually transferred return value of the library call Return type int pyvisa constants StatusCode resource_manager None Default ResourceManager instance for this library set_attribute session attribute attribute_state Sets the state of an attribute Corresponds to viSetAttribute function of the VISA library Parameters e session Unique logical identifier to a session e attribute Attribute for which the state is to be modified Attributes e attribute_state The state of the attribute to be set for the specified object Returns return value of the library call Return type pyvisa constants StatusCode set_buffer session mask size Sets the size for the formatted I O and
180. ion Unique logical identifier to a session e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e extended Use 64 bits offset independent of the platform Returns Data read from memory return value of the library call Return type int pyvisa constants StatusCode in_32 session space offset extended False Reads in an 32 bit value from the specified memory space and offset Corresponds to viln32 function of the VISA library Parameters e session Unique logical identifier to a session e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e extended Use 64 bits offset independent of the platform Returns Data read from memory return value of the library call Return type int opyvisa constants StatusCode in_64 session space offset extended False Reads in an 64 bit value from the specified memory space and offset Corresponds to viln64 function of the VISA library Parameters e session Unique logical identifier to a session e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e extended Use 64 bits offset independent of the platform Returns Data read from memory return value of the library call Return type int pyvisa constants StatusCode in_8
181. ions if None defaults to self query_delay Return type bytes query delay 0 0 query_values message delay None Query the device for values returning an iterable of values The datatype expected is obtained from values_format Parameters e message str the message to send e delay delay in seconds between write and read operations if None defaults to self query_delay Returns the answer from the device Return type list read termination None encoding None Read a string from the device Reading stops when the device stops sending e g by setting appropriate bus lines or the termination characters sequence was detected Attention Only the last character of the termination characters is really 3 6 API 79 PyVISA Documentation Release 1 9 dev0 used to stop reading however the whole sequence is compared to the ending of the read string message If they don t match a warning is issued All line ending characters are stripped from the end of the string Return type str read_raw size None Read the unmodified string sent from the instrument to the computer In contrast to read no termination characters are stripped Return type bytes read_stb Service request status register read_termination Read termination character read_termination_context args kwds read_values fmt None container lt type list gt Read a list of floating point values from the device Parameters
182. is in milliseconds None means waiting forever if necessary e capture_timeout When True will not produce a VisalOError VI_ERROR_TMO but instead return a WaitResponse with timed_out True Returns A WaitResponse object that contains event_type context and ret value class pyvisa resources FirewireInstrument resource_manager resource_name Communicates with to devices of type VXI VXI logical address INSTR More complex resource names can be specified with the following grammar VXI board VXI logical ad dress INSTR Do not instantiate directly use pyvisa highlevel ResourceManager open_resource 3 6 API 133 PyVISA Documentation Release 1 9 dev0 before_close Called just before closing an instrument clear Clears this resource close Closes the VISA session and marks the handle as invalid disable_event event_type mechanism Disables notification of the specified event type s via the specified mechanism s Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be disabled Con stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR VI_ALL_MECH discard_events event_type mechanism Discards event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be dicarded Con stants VI_QUEUE VI_HNDLR VI_SUS
183. isplay purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_LATTR_RSRC_NAME 3221159938 serial_number VI_ATTR_USB_SERIAL_NUM specifies the USB serial number of this device VISA Attribute VI_LATTR_USB_SERIAL_NUM 3221160352 session Resource session handle Raises pyvisa errors InvalidSession if session is closed 114 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 set_visa_attribute name state Sets the state of an attribute Parameters e name Attribute for which the state is to be modified Attributes e state The state of the attribute to be set for the specified object spec_version VI_ATTR_RSRC_SPEC_VERSION is the resource version that uniquely identifies the version of the VISA specification to which the implementation is compliant The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version The current VISA specification defines the value to be 00300000h VISA Attribute VI_LATTR_RSRC_SPEC_VERSION 1073676656 Type int Range 0 lt value lt 4294967295 stb Service request status register timeout The timeout in milliseconds for all resource I O operations Special values immediate VI_TMO_IMMEDIATE 0 for convenience any valu
184. lInstrument pyvisa resources TCPIPSocket pyvisa resources USBInstrument pyvisa resources USBRaw pyvisa resources TCPIPSocket pyvisa resources USBRaw pyvisa highlevel VisaLibraryBase pyvisa resources PXIInstrument Index 193 PyVISA Documentation Release 1 9 dev0 write_memory pyvisa resources VXIMemory method 162 write_raw pyvisa resources GPIBInstrument method 126 write_raw pyvisa resources MessageBasedResource method 68 write_raw pyvisa resources SerialInstrument method 83 write_raw pyvisa resources TCPIPInstrument method 91 write_raw pyvisa resources TCPIPSocket method 99 write_raw pyvisa resources USBInstrument method 108 write_raw pyvisa resources USBRaw method 117 write_termination pyvisa resources GPIBInstrument at tribute 126 write_termination pyvisa resources MessageBasedResource attribute 68 write_termination pyvisa resources SerialInstrument at tribute 83 write_termination pyvisa resources TCPIPInstrument at tribute 91 write_termination pyvisa resources TCPIPSocket at tribute 99 write_termination pyvisa resources USBInstrument at tribute 108 write_termination pyvisa resources USBRaw attribute 117 write_values pyvisa resources GPIBInstrument method 126 write_values pyvisa resources MessageBasedResource method 68 write_values pyvisa resources SerialInstrument method 83 write_v
185. lInstrument attribute 74 CR pyvisa resources TCPIPInstrument attribute 84 CR pyvisa resources TCPIPSocket attribute 92 CR pyvisa resources USBInstrument attribute 99 CR pyvisa resources USBRaw attribute 109 D data_bits pyvisa resources SerialInstrument attribute 75 destination_increment pyvisa resources PXIInstrument attribute 139 destination_increment pyvisa resources PXIMemory at tribute 145 destination_increment pyvisa resources VXIInstrument attribute 151 destination_increment pyvisa resources VXIMemory at tribute 157 disable_event method 34 disable_event pyvisa resources FirewireInstrument method 134 disable_event pyvisa resources GPIB Instrument method 118 disable_event method 127 disable_event pyvisa resources MessageBasedResource method 61 disable_event method 139 disable_event pyvisa resources PXIMemory method 145 disable_event pyvisa resources RegisterBasedResource method 68 pyvisa highlevel VisaLibraryBase pyvisa resources GPIBInterface pyvisa resources PXIInstrument 178 Index PyVISA Documentation Release 1 9 dev0 disable_event pyvisa resources Resource method 57 disable_event pyvisa resources SerialInstrument method 75 disable_event method 85 disable_event pyvisa resources TCPIPSocket method 92 disable_event method 100 disable_event pyvisa resources USBRaw method 109 disabl
186. lass pyvisa resources PXIInstrument resource_manager resource_name Communicates with to devices of type PXI lt device gt INSTR More complex resource names can be specified with the following grammar PX bus device function INSTR or PXI interface bus device function INSTR or PXI interface CHASSISchassis number SLOTslot number FUNCfunction INSTR Do not instantiate directly use pyvisa highlevel ResourceManager open_resource allow_dma This attribute specifies whether I O accesses should use DMA VI_TRUE or Programmed I O VI_FALSE In some implementations this attribute may have global effects even though it is documented to be a local attribute Since this affects performance and not functionality that behavior is acceptable VISA Attribute VI_LATTR_DMA_ALLOW_EN 1073676318 Type bool before_close Called just before closing an instrument clear Clears this resource close Closes the VISA session and marks the handle as invalid destination_increment VI ATTR_DEST_INCREMENT is used in the viMoveOutXX operations to specify by how many elements the destination offset is to be incremented after every transfer The default value of this attribute is 1 that is the destination address will be incremented by 1 after each transfer and the viMoveOutXX operations move into consecutive elements If this attribute is set to 0 the viMove OutXX operations will always write to the sam
187. led by a client appli cation e user_handle A value specified by an application that can be used for identifying handlers uniquely for an event type Returns user handle a ctypes object interface_number VI_ATTR_INTF_NUM specifies the board number for the given interface VISA Attribute VI_ATTR_INTF_NUM 1073676662 Type int Range 0 lt value lt 65535 interface_type The interface type of the resource as a number io_protocol VI_ATTR_IO_PROT specifies which protocol to use In VXI you can choose normal word serial or fast data channel FDC In GPIB you can choose normal or high speed HS 488 transfers In serial TCPIP or USB RAW you can choose normal transfers or 488 2 defined strings In USB INSTR you can choose normal or vendor specific transfers VISA Attribute VI_ATTR_IO_PROT 1073676316 Type int Range 0 lt value lt 65535 3 6 API 93 PyVISA Documentation Release 1 9 dev0 last_status Last status code for this session Return type pyvisa constants StatusCode lock timeout u default requested_key None Establish a shared lock to the resource Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key Access key used by another session with which you want your ses sion to share a lock or None to generate a new shared access key Returns A new
188. level VisaLibraryBase method 33 close pyvisa resources FirewireInstrument method 134 close pyvisa resources GPIBInstrument method 117 close pyvisa resources GPIBInterface method 127 close pyvisa resources MessageBasedResource method 61 close pyvisa resources PXIInstrument method 139 close pyvisa resources PXIMemory method 145 close pyvisa resources RegisterBasedResource method 68 close pyvisa resources Resource method 57 close pyvisa resources SerialInstrument method 75 close pyvisa resources TCPIPInstrument method 84 close pyvisa resources TCPIPSocket method 92 close pyvisa resources USBInstrument method 99 close pyvisa resources USBRaw method 109 close pyvisa resources VXIBackplane method 163 close pyvisa resources VXIInstrument method 151 close pyvisa resources VXIMemory method 157 control_atn pyvisa resources GPIB Instrument method 117 control_atn Q pyvisa resources GPIBInterface method 127 control_inQ pyvisa resources USBInstrument method 99 control_ren pyvisa resources GPIB Instrument method 118 control_ren pyvisa resources GPIBInterface method 127 control_ren pyvisa resources TCPIPInstrument method 84 control_ren pyvisa resources USBInstrument method 100 CR pyvisa resources GPIBInstrument attribute 117 CR pyvisa resources MessageBasedResource attribute 61 CR pyvisa resources Seria
189. level VisaLibraryBase method 48 poke_8 pyvisa highlevel VisaLibraryBase method 48 primary_address pyvisa resources GPIBInstrument at tribute 121 primary_address pyvisa resources GPIBInterface at tribute 131 protocol4882_strs pyvisa constants IOProtocol at tribute 168 pxi pyvisa constants InterfaceType attribute 168 PXIInstrument class in pyvisa resources 139 PXIMemory class in pyvisa resources 145 pyvisa constants module 167 Q query pyvisa resources GPIBInstrument method 121 query pyvisa resources MessageBasedResource method 64 query pyvisa resources Seriallnstrument method 78 query pyvisa resources TCPIPInstrument method 87 query pyvisa resources TCPIPSocket method 94 query pyvisa resources USBInstrument method 103 query pyvisa resources USBRaw method 112 query_ascii_values pyvisa resources GPIB Instrument method 121 query_ascii_values pyvisa resources MessageBasedResource method 64 186 Index PyVISA Documentation Release 1 9 dev0 query_ascii_values pyvisa resources SerialInstrument method 79 query_ascii_values pyvisa resources TCPIPInstrument method 87 query_ascii_values pyvisa resources TCPIPSocket method 95 query_ascii_values method 103 query_ascii_values method 112 query_binary_values pyvisa resources GPIB Instrument method 121 pyvisa resources USBInstrument pyvisa resources USB
190. library call Return type str pyvisa constants StatusCode map_address session map_space map_base map_size access False suggested None Maps the specified memory space into the process s address space Corresponds to viMapAddress function of the VISA library Parameters session Unique logical identifier to a session map_space Specifies the address space to map Constants SPACE map_base Offset in bytes of the memory to be mapped map_size Amount of memory to map in bytes access suggested If not Constants VI_NULL 0 the operating system attempts to map the memory to the address specified in suggested There is no guarantee however that the memory will be mapped to that address This operation may map the memory into an address region different from suggested Returns address in your process space where the memory was mapped return value of the library call Return type address pyvisa constants StatusCode map_trigger session trigger_source trigger_destination mode Map the specified trigger source line to the specified destination line Corresponds to viMapTrigger function of the VISA library Parameters e session Unique logical identifier to a session e trigger_source Source line from which to map Constants VI_TRIG e trigger_destination Destination line to which to map Constants VI_TRIG mode Returns return value of the library call Return typ
191. licable lock_excl timeout u default Establish an exclusive lock to the resource Parameters timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout lock_state VIATTR_RSRC_LOCK_STATE indicates the current locking state of the resource The resource can be unlocked locked with an exclusive lock or locked with a shared lock VISA Attribute VI_LATTR_RSRC_LOCK_STATE 1073676292 Type class pyvisa constants AccessModes open access_mode lt AccessModes no_lock 0 gt open_timeout 5000 Opens a session to the specified resource Parameters e access_mode pyvisa constants AccessModes Specifies the mode by which the resource is to be accessed e open_timeout int Milliseconds before the open operation times out 120 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 pass_control primary_address secondary_address Tell the GPIB device at the specified address to become controller in charge CIC Corresponds to viGpibPassControl function of the VISA library Parameters e primary address Primary address of the GPIB device to which you want to pass control e secondary address Secondary address of the targeted GPIB device If the tar geted device does not have a secondary address this parameter should contain the value Constants NO_SEC_ADDR Returns return value of
192. mapped from the foreign library as bound methods Each middle level function wraps one low level function In this case gt gt gt rm visalib map_address lt here goes the arguments gt The calling convention and types are handled by the wrapper 2 9 Architecture 19 PyVISA Documentation Release 1 9 dev0 20 Chapter 2 User guide CHAPTER 3 More information 3 1 VISA resource names If you use the function open_resource you must tell this function the VISA resource name of the instrument you want to connect to Generally it starts with the bus type followed by a double colon followed by the number within the bus For example GPIB 10 denotes the GPIB instrument with the number 10 If you have two GPIB boards and the instrument is connected to board number 1 you must write GPIB1 10 As for the bus things like GPIB USB ASRL for serial parallel interface are possible So for connecting to an instrument at COM2 the resource name is ASRL2 Since only one instrument can be connected with one serial interface there is no double colon parameter However most VISA systems allow aliases such as COM2 or LPT1 You may also add your own aliases The resource name is case insensitive It doesn t matter whether you say ASRL2 or asr12 For further infor mation I have to refer you to a comprehensive VISA description like http
193. mber for the given interface VISA Attribute VI_ATTR_INTF_NUM 1073676662 Type int Range 0 lt value lt 65535 interface_type The interface type of the resource as a number last_status Last status code for this session Return type pyvisa constants StatusCode lock timeout u default requested_key None Establish a shared lock to the resource Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key Access key used by another session with which you want your ses sion to share a lock or None to generate a new shared access key Returns A new shared access key if requested_key is None otherwise same value as the re quested_key lock_context args kwds A context that locks Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key When using default of exclusive the lock is an exclusive lock Otherwise it is the access key for the shared lock or None to generate a new shared access key The returned context is the access_key if applicable lock_excl timeout u default Establish an exclusive lock to the resource Parameters timeout Absolute time period in milliseconds that a resource waits to get unlocked by the lockin
194. me Unique symbolic name of a resource Return type pyvisa highlevel ResourceInfo resource_manufacturer_name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_MANF_NAME 3221160308 resource _ name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes 3 6 API 165 PyVISA Documentation Release 1 9 dev0 Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_NAME 3221159938 session Resource session handle Raises pyvisa errors InvalidSession if session is closed set_visa_attribute name state Sets the state of an attribute Parameters e name Attribute for which the state is to be modified Attributes e state The state of the attribute to be set for the specified object spec_version VI_ATTR_RSRC_SPEC_VERSION is the resource version that uniquely identifies the version
195. ment See struct module e is_big_endian boolean indicating endianess Defaults to False e container container type to use for the output data e delay delay in seconds between write and read operations if None defaults to self query_delay Return type bytes query delay 0 0 query_values message delay None Query the device for values returning an iterable of values The datatype expected is obtained from values_format Parameters e message str the message to send e delay delay in seconds between write and read operations if None defaults to self query_delay Returns the answer from the device Return type list read termination None encoding None Read a string from the device Reading stops when the device stops sending e g by setting appropriate bus lines or the termination characters sequence was detected Attention Only the last character of the termination characters is really used to stop reading however the whole sequence is compared to the ending of the read string message If they don t match a warning is issued All line ending characters are stripped from the end of the string Return type str 104 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 read_raw size None Read the unmodified string sent from the instrument to the computer In contrast to read no termination characters are stripped Return type bytes read_stb Service request status r
196. mentation Release 1 9 dev0 Range 0 lt value lt 4294967295 install_handler event_type handler user_handle None Installs handlers for event callbacks in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be installed by a client appli cation e user_handle A value specified by an application that can be used for identifying handlers uniquely for an event type Returns user handle a ctypes object interface_number VI_ATTR_INTF_NUM specifies the board number for the given interface VISA Attribute VI_ATTR_INTF_NUM 1073676662 Type int Range 0 lt value lt 65535 interface_type The interface type of the resource as a number last_status Last status code for this session Return type pyvisa constants StatusCode lock timeout u default requested_key None Establish a shared lock to the resource Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key Access key used by another session with which you want your ses sion to share a lock or None to generate a new shared access key Returns A new shared access key if requested_key is None otherwise same value as the re quested_key lock_context args kwds A context that locks Parameters e timeout Absolute time period
197. mode pyvisa constants AccessModes Specifies the mode by which the resource is to be accessed e open_timeout int Milliseconds before the open operation times out pass_control primary_address secondary_address Tell the GPIB device at the specified address to become controller in charge CIC Corresponds to viGpibPassControl function of the VISA library Parameters e primary address Primary address of the GPIB device to which you want to pass control 130 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 e secondary address Secondary address of the targeted GPIB device If the tar geted device does not have a secondary address this parameter should contain the value Constants NO_SEC_ADDR Returns return value of the library call Return type VISAStatus primary address VIATTR_GPIB_PRIMARY_ADDR specifies the primary address of the GPIB device used by the given session For the GPIB INTFC Resource this attribute is Read Write VISA Attribute VI_ATTR_GPIB_PRIMARY_ADDR 1073676658 Type int Range 0 lt value lt 30 register interface_type resource_class remote_enabled VI_ATTR_GPIB_REN_STATE returns the current state of the GPIB REN Remote ENable inter face line VISA Attribute VI_ATTR_GPIB_REN_STATE 1073676673 Type class pyvisa constants LineState resource_class VI_ATTR_RSRC_CLASS specifies the resource class for example INSTR as defined by the can
198. mory attribute 149 resource_info pyvisa resources RegisterBasedResource attribute 72 resource_info pyvisa resources Resource attribute 59 resource_info pyvisa resources Seriallnstrument at tribute 80 resource_info pyvisa resources TCPIPInstrument at tribute 89 resource_info pyvisa resources TCPIPSocket attribute 96 resource_info pyvisa resources USBInstrument at tribute 105 resource_info pyvisa resources USBRaw attribute 114 resource_info pyvisa resources V XIBackplane attribute 165 resource_info pyvisa resources VXIInstrument at tribute 154 resource_info pyvisa resources VXIMemory attribute 160 resource_info pyvisa highlevel ResourceManager method 56 resource_manager pyvisa highlevel VisaLibraryBase at tribute 50 resource_manufacturer_name pyvisa resources FirewireInstrument at tribute 137 resource_manufacturer_name pyvisa resources GPIBInstrument attribute 123 resource_manufacturer_name pyvisa resources GPIBInterface attribute 131 resource_manufacturer_name pyvisa resources MessageBasedResource attribute 66 resource_manufacturer_name pyvisa resources PXIInstrument attribute 143 resource_manufacturer_name pyvisa resources PXIMemory attribute 149 resource_manufacturer_name pyvisa resources RegisterBasedResource attribute 72 resource_manufacturer_name pyvisa resources Resource attribute 59 resource_manufacturer_name pyvisa r
199. n Pll explain the program step by step First we have to initialise the instrument gt gt gt keithley rm open_resource GPIB 12 gt gt gt keithley write rst status preset xcls Here we create the instrument variable keithley which is used for all further operations on the instrument Immediately after it we send the initialisation and reset message to the instrument 10 Chapter 2 User guide PyVISA Documentation Release 1 9 dev0 The next step is to write all the measurement parameters in particular the interval time 500ms and the number of readings 10 to the instrument I won t explain it in detail Have a look at an SCPI and or Keithley 2000 manual gt gt gt interval_in_ms 500 gt gt gt number_of_readings 10 gt gt gt keithley write status measurement enable 512 xsre 1 gt gt gt keithley write sample count d number_of_readings gt gt gt keithley write trigger source bus gt gt gt keithley write trigger delay f interval_in_ms 1000 0 gt gt gt keithley write trace points sd number_of_readings gt gt gt keithley write trace feed sensel feed control next Okay now the instrument is prepared to do the measurement The next three lines make the instrument waiting for a trigger pulse trigger it and wait until it sends a service request gt gt gt keithley write initiate gt gt
200. n defines the value to be 00300000h VISA Attribute VI_LATTR_RSRC_SPEC_VERSION 1073676656 Type int Range 0 lt value lt 4294967295 timeout The timeout in milliseconds for all resource I O operations Special values immediate VI_TMO_IMMEDTATE 0 for convenience any value smaller than 1 is considered as 0 infinite VI_TMO_INFINITE float inf for convenience None is considered as float inf To set an infinite timeout you can also use gt gt gt del instrument timeout uninstall_handler event_type handler user_handle None Uninstalls handlers for events in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be uninstalled by a client application e user_handle The user handle ctypes object or None returned by install_handler unlock Relinquishes a lock for the specified resource visa_attributes_classes lt class pyvisa attributes AttrVI_ATTR_RM_SESSION gt lt class pyvisa attributes At wait_on_event in_event_type timeout capture_timeout False Waits for an occurrence of the specified event in this resource Parameters e in_event_type Logical identifier of the event s to wait for e timeout Absolute time period in time units that the resource shall wait for a specified event to occur before returning the time elapsed error The time unit
201. n XON character has been received VISA Attribute VI_LATTR_ASRL_ALLOW_TRANSMIT 1073676734 Type bool assert_trigger Sends a software trigger to the device baud_rate VI_ATTR_ASRL_BAUD is the baud rate of the interface It is represented as an unsigned 32 bit in teger so that any baud rate can be used but it usually requires a commonly used rate such as 300 1200 2400 or 9600 baud VISA Attribute VI_ATTR_ASRL_BAUD 1073676321 Type int Range 0 lt value lt 4294967295 before_close Called just before closing an instrument break_length This controls the duration in milliseconds of the break signal asserted when VI_ATTR_ASRL_END_OUT is set to VILASRL_END_BREAK If you want to control the assertion state and length of a break signal manually use the VI_ATTR_ASRL_BREAK_ STATE attribute instead VISA Attribute VI_LATTR_ASRL_BREAK_LEN 1073676733 Type int Range 32768 lt value lt 32767 break_state 74 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 If set to VI_STATE_ASSERTED it suspends character transmission and places the transmission line in a break state until this attribute is reset to VI_LSTATE_UNASSERTED This attribute lets you manually control the assertion state and length of a break signal If you want VISA to send a break signal after each write operation automatically use the VI_LATTR_ASRL_BREAK_LEN and VI_ATTR_ASRL_END_OUT attributes instead VISA At
202. n of the VISA library Parameters e session Unique logical identifier to a session e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be disabled stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR VI_ALL_MECH Returns return value of the library call Return type pyvisa constants StatusCode discard_events session event_type mechanism Discards event occurrences for specified event types and mechanisms in a session Corresponds to viDiscardEvents function of the VISA library Parameters e session Unique logical identifier to a session e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be discarded stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR VI_ALL_MECH Returns return value of the library call Return type pyvisa constants StatusCode enable_event session event_type mechanism context None Enable event occurrences for specified event types and mechanisms in a session Corresponds to viEnableEvent function of the VISA library Parameters e session Unique logical identifier to a session e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be enabled stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR e context Returns return value of the library call Return type pyvisa constants StatusCode Con Con Con 34 Chapter 3 More information PyVI
203. n_version VI_ATTR_RSRC_IMPL_VERSION is the resource version that uniquely identifies each of the dif ferent revisions or implementations of a resource This attribute value is defined by the individual manufacturer and increments with each new revision The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version VISA Attribute VI_ATTR_RSRC_IMPL_VERSION 1073676291 Type int Range 0 lt value lt 4294967295 install_handler event_type handler user_handle None Installs handlers for event callbacks in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be installed by a client appli cation e user_handle A value specified by an application that can be used for identifying handlers uniquely for an event type Returns user handle a ctypes object 152 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 interface_number VI_ATTR_INTF_NUM specifies the board number for the given interface VISA Attribute VI_ATTR_INTF_NUM 1073676662 Type int Range 0 lt value lt 65535 interface_type The interface type of the resource as a number io_protocol VI_ATTR_IO_PROT specifies which protocol to use In VXI you can choose normal word serial or fast data channel FDC In GPIB yo
204. n_version pyvisa resources Resource at tribute 58 implementation_version pyvisa resources SerialInstrument attribute 76 implementation_version pyvisa resources TCPIPInstrument attribute 85 implementation_version pyvisa resources TCPIPSocket attribute 93 implementation_version pyvisa resources USBInstrument attribute 101 implementation_version pyvisa resources USBRaw at tribute 110 implementation_version pyvisa resources VXIBackplane attribute 163 implementation_version pyvisa resources VXIInstrument attribute 152 implementation_version pyvisa resources VXIMemory attribute 158 in_16 pyvisa highlevel VisaLibraryBase method 37 in_32 pyvisa highlevel VisaLibraryBase method 37 in_64 pyvisa highlevel VisaLibraryBase method 37 in_8 pyvisa highlevel VisaLibraryBase method 37 install_handler pyvisa highlevel VisaLibrary Base method 38 install_handler pyvisa resources FirewireInstrument method 135 install_handler pyvisa resources GPIB Instrument method 119 install_handler method 128 install_handler pyvisa resources MessageBasedResource method 62 install_handler method 140 install_handler pyvisa resources PXIMemory method 146 install_handler pyvisa resources RegisterBasedResource method 69 install_handler pyvisa resources Resource method 58 pyvisa resources GPIBInterface pyvisa resources PXIInstrument 182 Inde
205. nates when all requested data is transferred or when an error occurs termination_break None The write transmits a break after all the characters for the write are sent termination_char None The transfer terminate by searching for appending the termination character class pyvisa constants InterfaceType The hardware interface asrl None Serial devices connected to either an RS 232 or RS 485 controller firewire None Firewire device 3 6 API 167 PyVISA Documentation Release 1 9 dev0 gpib None GPIB Interface gpib_vxi None GPIB VXI VME eXtensions for Instrumentation pxi None PXI device rio None Rio device rsnrp None Rohde and Schwarz Device via Passport tcpip None TCPIP device usb None Universal Serial Bus USB hardware bus vxi None VXI VME eXtensions for Instrumentation VME MXI Multisystem eXtension Interface class pyvisa constants AddressState class pyvisa constants IOProtocol fdc None Fast data channel FDC protocol for VXI hs 488 None High speed 488 transfer for GPIB protocol4882_strs None 488 style transfer for serial usbtmc_vendor None Test measurement class vendor specific for USB class pyvisa constants LineState class pyvisa constants StatusCode Specifies the status codes that NI VISA driver level operations can return error_abort None The operation was aborted error_allocation None Insufficient system resou
206. ncoding None Write a string message to the device The write_termination is always appended to it Parameters message unicode Py2 or str Py3 the message to be sent Returns number of bytes written Return type int write_ascii_values message values converter u f separator u termination None encod ing None Write a string message to the device followed by values in ascii format The write_termination is always appended to it Parameters e message unicode Py2 or str Py3 the message to be sent e values data to be writen to the device e converter callable str function used to convert each value String formatting codes are also accepted Defaults to str e separator a callable that split the str into individual elements If a str is given data split separator is used Type separator collections Iterable T gt str str Returns number of bytes written 98 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 Return type int write_binary values message values datatype u f is_big_endian False termination None encoding None Write a string message to the device followed by values in binary format The write_termination is always appended to it Parameters e message unicode Py2 or str Py3 the message to be sent e values data to be writen to the device e datatype the format string for a single element See struct modul
207. ndently of the interface e g GPIB RS232 USB Ethernet As an example reading self identification from a Keithley Multimeter with GPIB number 12 is as easy as three lines of Python code gt gt gt import visa gt gt gt rm visa ResourceManager gt gt gt rm list_resources ASRL1 INSTR ASRL2 INSTR GPIBO 12 INSTR gt gt gt inst rm open_resource GPIBO 12 INSTR gt gt gt print inst query IDN That s the whole program really It works on Windows Linux and Mac with arbitrary adapters e g National Instruments Agilent Tektronix Stanford Research Systems Contents 1 PyVISA Documentation Release 1 9 dev0 2 Contents CHAPTER 1 General overview The programming of measurement instruments can be real pain There are many different protocols sent over many different interfaces and bus systems e g GPIB RS232 USB Ethernet For every programming language you want to use you have to find libraries that support both your device and its bus system In order to ease this unfortunate situation the Virtual Instrument Software Architecture VISA specification was de fined in the middle of the 90ies VISA is a standard for configuring programming and troubleshooting instrumentation systems comprising GPIB VXI PXI Serial Ethernet and or USB interfaces Today VISA is implemented on all significant operating systems A couple of vendors offer VISA
208. ndler user_handle None def unlock self session def unmap_address self session def unmap_trigger self session trigger_source trigger_destination def usb_control_in self session request_type_bitmap_field request_id request_value def usb_control_out self session request_type_bitmap_field request_id request_value def vxi_command_query self session mode command def wait_on_event self session in_event_type timeout def write self session data def write_asynchronously self session data def write_from_file self session filename count 2 8 PyVISA Shell The shell moved into PyVISA from the Lantz Project is a text based user interface to interact with instruments You can invoke it from the command line python m visa shell that will show something the following prompt Welcome to the VISA shell Type help or to list commands visa At any time you can type or help to get a list of valid commands visa help Documented commands type help lt topic gt 16 Chapter 2 User guide PyVISA Documentation Release 1 9 dev0 EOF attr close exit help list open query visa help list List all connected resources read write Tab completion is also supported The most basic task is listing all connected devices visa list 0 ASRL
209. necessary e capture_timeout When True will not produce a VisalOError VI_LERROR_TMO but instead return a WaitResponse with timed_out True Returns A WaitResponse object that contains event_type context and ret value write message termination None encoding None Write a string message to the device The write_termination is always appended to it Parameters message unicode Py2 or str Py3 the message to be sent Returns number of bytes written Return type int write_ascii_values message values converter u f separator u termination None encod ing None Write a string message to the device followed by values in ascii format The write_termination is always appended to it Parameters e message unicode Py2 or str Py3 the message to be sent e values data to be writen to the device e converter callable str function used to convert each value String formatting codes are also accepted Defaults to str e separator a callable that split the str into individual elements If a str is given data split separator is used Type separator collections Iterable T gt str str Returns number of bytes written Return type int write_binary values message values datatype u f is_big_endian False termination None encoding None Write a string message to the device followed by values in binary format The write_termination is always appended to it Parameters e m
210. nstants Ignoring warnings context manager for the current resource Parameters warnings_constants constants identifying the warnings to ignore implementation_version VIATTR_RSRC_IMPL_VERSION is the resource version that uniquely identifies each of the dif ferent revisions or implementations of a resource This attribute value is defined by the individual manufacturer and increments with each new revision The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version VISA Attribute VI_ATTR_RSRC_IMPL_VERSION 1073676291 Type int Range 0 lt value lt 4294967295 install_handler event_type handler user_handle None Installs handlers for event callbacks in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be installed by a client appli cation 146 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 e user_handle A value specified by an application that can be used for identifying handlers uniquely for an event type Returns user handle a ctypes object interface_number VI_ATTR_INTF_NUM specifies the board number for the given interface VISA Attribute VI_ATTR_INTF_NUM 1073676662 Type int Range 0 lt value lt 65535 interface_type The interface type of the resourc
211. nstrument with instrument number 14 so you ask the ResourceManager to open GPIBO 14 INSTR and assign the returned object to the my_instrument Notice open_resource has given you an instance of GPIBInstrument class a subclass of the more generic Resource gt gt gt print my_instrument lt GPIBInstrument GPIB 14 gt There many Resource subclasses representing the different types of resources but you do not have to worry as the ResourceManager will provide you with the appropiate class You can check the methods and attributes of each class in the Resource classes Then you query the device with the following message IDN Which is the standard GPIB message for what are you or in some cases what s on your display at the moment query is a short form for a write operation to send a message followed by a read So gt gt gt my_instrument query IDN is the same as gt gt gt my_instrument write xIDN gt gt gt print my_instrument read 2 3 2 Example for serial RS232 device Consider an Oxford ITC4 temperature controller which is connected through COM2 with my computer The following code prints its self identification on the screen itc4 rm open_resource COM2 itc4 write V print itc4 read 2 3 Tutorial 7 PyVISA Documentation Release 1 9 dev0 Instead of separate
212. nt Milliseconds before the open operation times out query message delay None A combination of write message and read Parameters e message str the message to send e delay delay in seconds between write and read operations if None defaults to self query_delay Returns the answer from the device Return type str query_ascii_values message converter u f separator u container lt type list gt de lay None Query the device for values in ascii format returning an iterable of values Parameters e message str the message to send 3 6 API 103 PyVISA Documentation Release 1 9 dev0 e delay delay in seconds between write and read operations if None defaults to self query_delay e converter callable function used to convert each element Defaults to float e separator a callable that split the str into individual elements If a str is given data split separator is used e container container type to use for the output data Type separator str gt collections Iterable int str Returns the answer from the device Return type list query binary values message datatype u f is_big_endian False container lt type list gt de lay None header_fmt w ieee Converts an iterable of numbers into a block of data in the ieee format Parameters e message the message to send to the instrument e datatype the format string for a single ele
213. nt attribute 76 EOI line 13 error_abort pyvisa constants StatusCode attribute 168 pyvisa highlevel VisaLibrary Base pyvisa resources PXIInstrument pyvisa resources USBInstrument pyvisa resources VXIInstrument attribute Index 179 PyVISA Documentation Release 1 9 dev0 error_allocation pyvisa constants StatusCode attribute 168 error_attribute_read_only attribute 168 error_bus_error pyvisa constants StatusCode attribute 168 error_closing_failed tribute 168 error_connection_lost pyvisa constants StatusCode at tribute 168 error_file_access pyvisa constants StatusCode attribute 168 error_file_i_o pyvisa constants StatusCode attribute 169 error_handler_not_installed pyvisa constants StatusCode attribute 169 error_in_progress pyvisa constants StatusCode at tribute 169 error_input_protocol_violation pyvisa constants StatusCode attribute 169 error_interface_number_not_configured pyvisa constants StatusCode attribute 169 error_interrupt_pending pyvisa constants StatusCode at tribute 169 error_invalid_access_key attribute 169 error_invalid_access_mode pyvisa constants StatusCode attribute 169 error_invalid_address_space pyvisa constants StatusCode attribute 169 error_invalid_context pyvisa constants StatusCode at tribute 169 error_invalid_degree attribute 169 error_invalid_event pyvisa constants StatusCode at tribute 169 error_invalid_expression
214. nt resource Parameters warnings_constants constants identifying the warnings to ignore implementation_version VIATTR_RSRC_IMPL_VERSION is the resource version that uniquely identifies each of the dif ferent revisions or implementations of a resource This attribute value is defined by the individual manufacturer and increments with each new revision The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version VISA Attribute VI_ATTR_RSRC_IMPL_VERSION 1073676291 Type int Range 0 lt value lt 4294967295 install_handler event_type handler user_handle None Installs handlers for event callbacks in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be installed by a client appli cation e user_handle A value specified by an application that can be used for identifying handlers uniquely for an event type Returns user handle a ctypes object interface_number VI_ATTR_INTF_NUM specifies the board number for the given interface VISA Attribute VI_ATTR_INTF_NUM 1073676662 Type int Range 0 lt value lt 65535 interface_type The interface type of the resource as a number io_protocol VI_ATTR_IO_PROT specifies which protocol to use In VXI you can choose normal word serial or fast data
215. nt takes a delay argument that adds a pause after each write operation This also can be changed using the delay attribute In PyVISA 1 6 delay is removed Delays after write operations must be added to the application code Instead a new attribute and argument query_delay is available This allows you to pause between write and read operations inside query Additionally query takes an optional argument called query allowing you to change it for each method call Deprecated term_chars and automatic removal of CR LF In the original PyVISA implementation Instrument takes a term_chars argument to change at the read and write termination characters If this argument is None CR LF is appended to each outgoing message and not expected for incoming messages although removed if present In PyVISA 1 6 term_chars is replaced by read_termination and write_termination In this way you can set independently the termination for each operation Automatic removal of CR LF is also gone in 1 6 3 3 Contributing to PyVISA You can contribute in different ways 3 3 1 Report issues You can report any issues with the package the documentation to the PyVISA issue tracker Also feel free to submit feature requests comments or questions In some cases platform specific information is required If you think this is the case run the following command and paste the output into the issue python m visa info It is useful th
216. nt_type Logical event identifier e mechanism Specifies event handling mechanisms to be dicarded Con stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR VI_ALL_MECH enable event event_type mechanism context None Enable event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be enabled Con stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR e context Not currently used leave as None enable _repeat_addressing VIATTR_GPIB_READDR_EN specifies whether to use repeat addressing before each read or write operation VISA Attribute VI_ATTR_GPIB_READDR_EN 1073676315 Type bool enable_unaddressing VI_ATTR_GPIB_UNADDR_EN specifies whether to unaddress the device UNT and UNL after each read or write operation VISA Attribute VI_ATTR_GPIB_UNADDR_EN 1073676676 Type bool 118 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 encoding Encoding used for read and write operations get_visa_attribute name Retrieves the state of an attribute in this resource Parameters name Resource attribute for which the state query is made see Attributes Returns The state of the queried attribute for a specified resource Return type unicode Py2 or str Py3 list or other type ignore_warning warnings_constants Ignoring warnings context manager for the curre
217. ntation Release 1 9 dev0 timeout The timeout in milliseconds for all resource I O operations Special values immediate VI_TMO_IMMEDTATE 0 for convenience any value smaller than 1 is considered as 0 infinite VI_TMO_ INFINITE float inf for convenience None is considered as float inf To set an infinite timeout you can also use gt gt gt del instrument timeout uninstall_handler event_type handler user_handle None Uninstalls handlers for events in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be uninstalled by a client application e user_handle The user handle ctypes object or None returned by install_handler unlock Relinquishes a lock for the specified resource visa_attributes_classes lt class pyvisa attributes AttrVI_ATTR_RM_SESSION gt lt class pyvisa attributes At wait_on_event in_event_type timeout capture_timeout False Waits for an occurrence of the specified event in this resource Parameters e in_event_type Logical identifier of the event s to wait for e timeout Absolute time period in time units that the resource shall wait for a specified event to occur before returning the time elapsed error The time unit is in milliseconds None means waiting forever if necessary e capture_timeout When True will not produce a Visal
218. number of bytes written Return type int write termination Writer termination character write_values message values termination None encoding None 108 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 class pyvisa resources USBRaw args kwargs Communicates with to devices of type USB manufacturer ID model code serial number RAW More complex resource names can be specified with the following grammar USB board manufacturer ID model code serial number USB interface number RAW Do not instantiate directly use pyvisa highlevel ResourceManager open_resource CR w r LF u n assert_trigger Sends a software trigger to the device before_close Called just before closing an instrument chunk_size 20480 clear Clears this resource close Closes the VISA session and marks the handle as invalid disable_event event_type mechanism Disables notification of the specified event type s via the specified mechanism s Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be disabled Con stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR VI_ALL_MECH discard_events event_type mechanism Discards event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be dica
219. oating point values from the device Parameters e fmt the format of the values If given it overrides the class attribute values_format Possible values are bitwise disjunctions of the above constants ascii single double and big_endian Default is ascii e container the output datatype Returns the list of read values Return type list register interface_type resource_class resource _class VI_ATTR_RSRC_CLASS specifies the resource class for example INSTR as defined by the canonical resource name VISA Attribute VI_LATTR_RSRC_CLASS 3221159937 resource_info Get the extended information of this resource Parameters resource_name Unique symbolic name of a resource Return type pyvisa highlevel ResourceInfo resource_manufacturer_name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_MANF_NAME 3221160308 resource _ name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for d
220. od 144 wait_on_event pyvisa resources PXIMemory method 150 wait_on_event pyvisa resources RegisterBasedResource method 73 wait_on_event pyvisa resources Resource method 61 wait_on_event pyvisa resources SerialInstrument pyvisa resources GPIB Interface pyvisa resources PXIInstrument method 82 wait_on_event pyvisa resources TCPIPInstrument method 90 wait_on_event pyvisa resources TCPIPSocket method 98 wait_on_event method 107 wait_on_event pyvisa resources USBRaw method 116 wait_on_event method 166 wait_on_event method 156 wait_on_event pyvisa resources VXIMemory method 162 warning_configuration_not_loaded pyvisa constants StatusCode attribute 173 warning_ext_function_not_implemented pyvisa constants StatusCode attribute 173 warning _nonsupported_attribute_state pyvisa constants StatusCode attribute 173 warning_nonsupported_buffer pyvisa constants StatusCode attribute 173 warning_null_object pyvisa constants StatusCode attribute 173 warning _queue_overflow attribute 173 pyvisa resources USBInstrument pyvisa resources VXIBackplane pyvisa resources V XIInstrument pyvisa constants StatusCode warning_unknown_status attribute 173 write pyvisa highlevel VisaLibraryBase method 54 write pyvisa resources GPIBInstrument method 125 write pyvisa resources MessageBasedResource method 67 write pyvisa resources Seri
221. ode poke_16 session address data Write an 16 bit value from the specified address Corresponds to viPoke16 function of the VISA library Parameters e session Unique logical identifier to a session e address Source address to read the value e data value to be written to the bus Returns return value of the library call Return type pyvisa constants StatusCode poke_32 session address data Write an 32 bit value from the specified address Corresponds to viPoke32 function of the VISA library Parameters e session Unique logical identifier to a session e address Source address to read the value e data value to be written to the bus Returns return value of the library call Return type pyvisa constants StatusCode poke_64 session address data Write an 64 bit value from the specified address Corresponds to viPoke64 function of the VISA library Parameters e session Unique logical identifier to a session e address Source address to read the value e data value to be written to the bus Returns return value of the library call Return type pyvisa constants StatusCode poke_8 session address data Write an 8 bit value from the specified address Corresponds to viPoke8 function of the VISA library Parameters e session Unique logical identifier to a session 48 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 e address Source address to re
222. of the VISA specification to which the implementation is compliant The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version The current VISA specification defines the value to be 00300000h VISA Attribute VI_LATTR_RSRC_SPEC_VERSION 1073676656 Type int Range 0 lt value lt 4294967295 timeout The timeout in milliseconds for all resource I O operations Special values immediate VI_TMO_IMMEDIATE 0 for convenience any value smaller than 1 is considered as 0 infinite VI_TMO_ INFINITE float inf for convenience None is considered as float inf To set an infinite timeout you can also use gt gt gt del instrument timeout uninstall_handler event_type handler user_handle None Uninstalls handlers for events in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be uninstalled by a client application e user_handle The user handle ctypes object or None returned by install_handler unlock Relinquishes a lock for the specified resource visa_attributes_classes lt class pyvisa attributes AttrVI_ATTR_RM_SESSION gt lt class pyvisa attributes At 166 Chapter 3 More information PyVISA Documentation Release 1 9 dev0
223. of the platform Returns Data read from the bus return value of the library call Return type list oyvisa constants StatusCode move_in_8 session space offset length extended False Moves an 8 bit block of data from the specified address space and offset to local memory Corresponds to viMoveln8 functions of the VISA library Parameters e session Unique logical identifier to a session e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e length Number of elements to transfer where the data width of the elements to transfer is identical to the source data width e extended Use 64 bits offset independent of the platform Returns Data read from the bus return value of the library call Return type list oyvisa constants StatusCode move_out session space offset length data width extended False Moves a block of data from local memory to the specified address space and offset Corresponds to viMoveOut functions of the VISA library Parameters e session Unique logical identifier to a session e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read 42 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 e length Number of elements to transfer where the data width of the elements to transfer is identical to the sour
224. ogrammatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_MANF_NAME 3221160308 resource _ name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_NAME 3221159938 session Resource session handle Raises pyvisa errors InvalidSession if session is closed set_visa_attribute name state Sets the state of an attribute Parameters e name Attribute for which the state is to be modified Attributes e state The state of the attribute to be set for the specified object source_increment VI ATTR_SRC_INCREMENT is used in the viMoveInXX operations to specify by how many ele ments the source offset is to be incremented after every transfer The default value of this attribute is 1 that is the source address will be incremented by 1 after each transfer and the viMoveInXX operations move from consecutive elements If this attribute is set to 0 the viMoveInXX operations will always read from the same element essentially treating the source as a FIFO register VISA Attribute VI_ATTR_SRC_INCREMENT 1073676352 Type int
225. olute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout lock_state VIATTR_RSRC_LOCK_STATE indicates the current locking state of the resource The resource can be unlocked locked with an exclusive lock or locked with a shared lock VISA Attribute VI_ATTR_RSRC_LOCK_STATE 1073676292 Type class pyvisa constants AccessModes open access_mode lt AccessModes no_lock 0 gt open_timeout 5000 Opens a session to the specified resource 3 6 API 63 PyVISA Documentation Release 1 9 dev0 Parameters e access_mode pyvisa constants AccessModes Specifies the mode by which the resource is to be accessed e open_timeout int Milliseconds before the open operation times out query message delay None A combination of write message and read Parameters e message str the message to send e delay delay in seconds between write and read operations if None defaults to self query_delay Returns the answer from the device Return type str query_ascii_values message converter u f separator u lay None Query the device for values in ascii format returning an iterable of values container lt type list gt de Parameters e message str the message to send e delay delay in seconds between write and read operations if None defaults to self query_delay e conver
226. onical resource name VISA Attribute VI_LATTR_RSRC_CLASS 3221159937 resource_info Get the extended information of this resource Parameters resource_name Unique symbolic name of a resource Return type pyvisa highlevel ResourceInfo resource_manufacturer_name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_MANF_NAME 3221160308 resource_name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes 3 6 API 131 PyVISA Documentation Release 1 9 dev0 Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_NAME 3221159938 secondary address VI ATTR_GPIB_SECONDARY_ADDR specifies the secondary address of the GPIB device used by the given session For the GPIB INTFC Resource this attribute is Read Write VISA Attribute VI_ATTR_GPIB_SECONDARY_ADDR 1073676659 Type int Range 0 lt value lt 30
227. ons of the visa library register interface_type resource_class resource _class VI_ATTR_RSRC_CLASS specifies the resource class for example INSTR as defined by the canonical resource name VISA Attribute VI_ATTR_RSRC_CLASS 3221159937 resource_info Get the extended information of this resource Parameters resource_name Unique symbolic name of a resource Return type pyvisa highlevel ResourceInfo resource_manufacturer_name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_MANF_NAME 3221160308 resource _ name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_NAME 3221159938 session Resource session handle Raises pyvisa errors InvalidSession if session is closed set_visa_attribute name state Sets the state of an attribute
228. or in 65535 send_command data Write GPIB command bytes on the bus Corresponds to viGpibCommand function of the VISA library Parameters data bytes data tor write Returns Number of written bytes return value of the library call Return type int VISAStatus send_end VIATTR_SEND_END_EN specifies whether to assert END during the transfer of the last byte of the buffer VISA Attribute VI_ATTR_SEND_END_EN 1073676310 Type bool send_ifc Pulse the interface clear line IFC for at least 100 microseconds Corresponds to viGpibSendIFC function of the VISA library Returns return value of the library call Return type VISAStatus session Resource session handle Raises pyvisa errors InvalidSession if session is closed set_visa_attribute name state Sets the state of an attribute Parameters e name Attribute for which the state is to be modified Attributes e state The state of the attribute to be set for the specified object spec_version VIATTR_RSRC_SPEC_VERSION is the resource version that uniquely identifies the version of the VISA specification to which the implementation is compliant The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the 132 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 version and the lowest 8 bits as the sub minor number of the version The current VISA specificatio
229. or low level I O communication buffer s Corresponds to viSetBuf function of the VISA library Parameters e session Unique logical identifier to a session e mask Specifies the type of buffer Constants VILREAD_BUF VI_WRITE_BUF VLIO_IN_BUF VI_IO_OUT_BUF e size The size to be set for the specified buffer s Returns return value of the library call Return type pyvisa constants StatusCode status_description session status Returns a user readable description of the status code passed to the operation Corresponds to viStatusDesc function of the VISA library Parameters e session Unique logical identifier to a session e status Status code to interpret Returns 50 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 e The user readable string interpretation of the status code passed to the operation e return value of the library call Return type e unicode Py2 or str Py3 e pyvisa constants StatusCode terminate session degree job_id Requests a VISA session to terminate normal execution of an operation Corresponds to viTerminate function of the VISA library Parameters e session Unique logical identifier to a session e degree Constants NULL e job_id Specifies an operation identifier Returns return value of the library call Return type pyvisa constants StatusCode uninstall_all_ visa_handlers session Uninstalls all previously installed handlers for a
230. ore information about VISA e The original VISA docs VISA specification scroll down to the end VISA library specification VISA specification for textual languages e The very good VISA manuals from National Instruments s VISA NI VISA User Manual 30 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 NI VISA Programmer Reference Manual NI VISA help file in HTML 3 5 NI VISA Installation In every OS the NI VISA library bitness i e 32 or 64 bit has to match the Python bitness So first you need to install a NI VISA that works with your OS and then choose the Python version matching the installed NI VISA bitness PyVISA includes a debugging command to help you troubleshoot this and other things python m visa info According to National Instruments NI VISA 5 4 1 is available for Note NI VISA is not available for your system take a look at the Frequently asked questions 3 5 1 Mac OS X Download NI VISA for Mac OS X Supports e Mac OS X 10 7 x x86 and x86 64 e Mac OS X 10 8 x 64 bit VISA applications are supported for a limited set of instrumentation buses The supported buses are ENET Serial USB and TCPIP Logging VISA operations in NI I O Trace from 64 bit VISA applications is not supported 3 5 2 Windows Download NI VISA for Windows Suports Windows Server 2003 R2 32 bit version only Windows Server 2008 R2 64 bit version only
231. otification of the specified event type s via the specified mechanism s Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be disabled Con stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR VI_ALL_MECH discard_events event_type mechanism Discards event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be dicarded Con stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR VI_ALL_MECH enable_event event_type mechanism context None Enable event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be enabled Con stants VI_QUEUE VI_LHNDLR VI_LSUSPEND_HNDLR 3 6 API 57 PyVISA Documentation Release 1 9 dev0 e context Not currently used leave as None get_visa_attribute name Retrieves the state of an attribute in this resource Parameters name Resource attribute for which the state query is made see Attributes Returns The state of the queried attribute for a specified resource Return type unicode Py2 or str Py3 list or other type ignore_warning warnings_constants Ignoring warnings context manager for the current resource Parameters warnings_constants constants identifying the
232. ources USBRaw method 115 uninstall_handler method 166 uninstall_handler method 156 uninstall_handler method 162 pyvisa resources SerialInstrument pyvisa resources TCPIPSocket pyvisa resources USBInstrument pyvisa resources VXIBackplane pyvisa resources VXIInstrument pyvisa resources VXIMemory USBInstrument class in pyvisa resources 99 USBRaw class in pyvisa resources 108 usbtmc_vendor pyvisa constants IOProtocol attribute 168 V values_format pyvisa resources GPIBInstrument at tribute 125 values_format pyvisa resources MessageBasedResource attribute 67 values_format pyvisa resources SerialInstrument at tribute 82 values_format pyvisa resources TCPIPInstrument attribute 90 values_format pyvisa resources TCPIPSocket attribute 98 values_format pyvisa resources USBInstrument at tribute 107 uninstall_visa_handler pyvisa highlevel VisaLibraryBase values_format pyvisa resources USBRaw attribute 116 method 51 unlock pyvisa highlevel VisaLibraryBase method 51 unlock pyvisa resources FirewireInstrument method 138 unlock pyvisa resources GPIBInstrument method 125 unlock pyvisa resources GPIBInterface method 133 unlock pyvisa resources MessageBasedResource method 67 unlock pyvisa resources PXIInstrument method 144 unlock pyvisa resources PXIMemory method 150 unlock pyvisa resources RegisterBasedResource method 73
233. parator a callable that split the str into individual elements If a str is given data split separator is used e container container type to use for the output data Type separator str gt collections Iterable int str Returns the answer from the device Return type list query binary values message datatype u f is_big_endian False container lt type list gt de lay None header_fmt w ieee Converts an iterable of numbers into a block of data in the ieee format Parameters e message the message to send to the instrument e datatype the format string for a single element See struct module 3 6 API 87 PyVISA Documentation Release 1 9 dev0 e is_big_endian boolean indicating endianess Defaults to False e container container type to use for the output data e delay delay in seconds between write and read operations if None defaults to self query_delay Return type bytes query delay 0 0 query_values message delay None Query the device for values returning an iterable of values The datatype expected is obtained from values_format Parameters e message str the message to send e delay delay in seconds between write and read operations if None defaults to self query_delay Returns the answer from the device Return type list read termination None encoding None Read a string from the device Reading stops when the device stops sending e g by setting
234. pyvisa constants AccessModes attribute 167 attribute pyvisa constants StatusCode at pyvisa constants StatusCode pyvisa constants StatusCode pyvisa constants StatusCode at F fdc pyvisa constants IOProtocol attribute 168 firewire pyvisa constants InterfaceType attribute 167 FirewireInstrument class in pyvisa resources 133 flow_control pyvisa resources SerialInstrument at tribute 76 flush pyvisa highlevel VisaLibraryBase method 34 flushQ pyvisa resources SerialInstrument method 76 G get_attribute method 35 get_debug_info pyvisa highlevel VisaLibrary Base static method 35 get_last_status_in_session pyvisa highlevel VisaLibraryBase method 35 get_library_paths pyvisa highlevel VisaLibraryBase static method 35 get_visa_attribute pyvisa resources FirewireInstrument method 134 get_visa_attribute pyvisa resources GPIB Instrument method 119 get_visa_attribute method 128 pyvisa highlevel VisaLibrary Base pyvisa resources GPIBInterface get_visa_attribute pyvisa resources MessageBasedResource method 62 get_visa_attribute method 140 get_visa_attribute method 146 pyvisa resources PXIInstrument pyvisa resources PXIMemory get_visa_attribute pyvisa resources RegisterBasedResource method 69 get_visa_attribute pyvisa resources Resource method 58 get_visa_attribute method 76 get_visa_attribute
235. pyvisa constants StatusCode attribute 172 success_nested_exclusive attribute 172 success_nested_shared pyvisa constants StatusCode at tribute 172 success_no_more_handler_calls_in_chain pyvisa constants StatusCode attribute 172 success_queue_already_empty pyvisa constants StatusCode attribute 172 success_queue_not_empty pyvisa constants StatusCode attribute 172 success_syncronous pyvisa constants StatusCode at tribute 172 pyvisa highlevel VisaLibrary Base pyvisa constants StatusCode success_termination_character_read pyvisa constants StatusCode attribute 173 success_trigger_already_mapped pyvisa constants StatusCode attribute 173 T tcpip pyvisa constants InterfaceType attribute 168 TCPIPInstrument class in pyvisa resources 84 TCPIPSocket class in pyvisa resources 92 terminate pyvisa highlevel VisaLibraryBase method 51 termination_break pyvisa constants SerialTermination attribute 167 termination_char pyvisa constants SerialTermination at tribute 167 timeout pyvisa resources FirewireInstrument attribute 138 timeout pyvisa resources GPIBInstrument attribute 124 timeout pyvisa resources GPIBInterface attribute 133 timeout pyvisa resources MessageBasedResource attribute 66 timeout pyvisa resources PXIInstrument attribute 144 timeout pyvisa resources PXIMemory attribute 150 timeout pyvisa resources RegisterBasedResource at tribute 72 tim
236. queried attribute for a specified resource Return type unicode Py2 or str Py3 list or other type ignore_warning warnings_constants Ignoring warnings context manager for the current resource Parameters warnings_constants constants identifying the warnings to ignore implementation_version 76 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 VIATTR_RSRC_IMPL_VERSION is the resource version that uniquely identifies each of the dif ferent revisions or implementations of a resource This attribute value is defined by the individual manufacturer and increments with each new revision The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version VISA Attribute VI_ATTR_RSRC_IMPL_VERSION 1073676291 Type int Range 0 lt value lt 4294967295 install_handler event_type handler user_handle None Installs handlers for event callbacks in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be installed by a client appli cation e user_handle A value specified by an application that can be used for identifying handlers uniquely for an event type Returns user handle a ctypes object interface_number VI_ATTR_INTF_NUM specifies the board number for the given interface V
237. r_handle None Uninstalls handlers for events in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be uninstalled by a client application e user_handle The user handle ctypes object or None returned by install_handler unlock Relinquishes a lock for the specified resource visa_attributes_classes lt class pyvisa attributes AttrVI_ATTR_RM_SESSION gt lt class pyvisa attributes At wait_on_event in_event_type timeout capture_timeout False Waits for an occurrence of the specified event in this resource Parameters e in_event_type Logical identifier of the event s to wait for e timeout Absolute time period in time units that the resource shall wait for a specified event to occur before returning the time elapsed error The time unit is in milliseconds None means waiting forever if necessary e capture_timeout When True will not produce a VisalOError VI_ERROR_TMO but instead return a WaitResponse with timed_out True Returns A WaitResponse object that contains event_type context and ret value write_memory space offset data width extended False Write in an 8 bit 16 bit 32 bit value to the specified memory space and offset Parameters e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e data Data to write to bus
238. rces to perform necessary memory allocation error_attribute_read_only None The specified attribute is read only error_bus_error None Bus error occurred during transfer error_closing_failed None Unable to deallocate the previously allocated data structures corresponding to this session or object refer ence error_connection_lost None The connection for the specified session has been lost 168 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 error_file_access None An error occurred while trying to open the specified file Possible causes include an invalid path or lack of access rights error _file_i_o None An error occurred while performing I O on the specified file error_handler_not_installed None A handler is not currently installed for the specified event error_in_progress None Unable to queue the asynchronous operation because there is already an operation in progress error_input_protocol_ violation None Device reported an input protocol error during transfer error_interface_number_not_configured None The interface type is valid but the specified interface number is not configured error_interrupt_pending None An interrupt is still pending from a previous call error_invalid_access_key None The access key to the resource associated with this session is invalid error _invalid_access_mode None Invalid access mode error_invalid_address_space None Invalid a
239. rded Con stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR VI_ALL_MECH enable_event event_type mechanism context None Enable event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be enabled Con stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR e context Not currently used leave as None encoding Encoding used for read and write operations get_visa_attribute name Retrieves the state of an attribute in this resource Parameters name Resource attribute for which the state query is made see Attributes Returns The state of the queried attribute for a specified resource 3 6 API 109 PyVISA Documentation Release 1 9 dev0 Return type unicode Py2 or str Py3 list or other type ignore_warning warnings_constants Ignoring warnings context manager for the current resource Parameters warnings_constants constants identifying the warnings to ignore implementation_version VIATTR_RSRC_IMPL_VERSION is the resource version that uniquely identifies each of the dif ferent revisions or implementations of a resource This attribute value is defined by the individual manufacturer and increments with each new revision The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest
240. retrieves the response to a previous query Corresponds to viVxiCommandQuery function of the VISA library Parameters e session Unique logical identifier to a session e mode Specifies whether to issue a command and or retrieve a response Con stants VI_VXI_CMD VI_VXI_RESP e command The miscellaneous command to send Returns The response retrieved from the device return value of the library call Return type int pyvisa constants StatusCode wait_on_event session in_event_type timeout Waits for an occurrence of the specified event for a given session Corresponds to viWaitOnEvent function of the VISA library Parameters e session Unique logical identifier to a session e in_event_type Logical identifier of the event s to wait for e timeout Absolute time period in time units that the resource shall wait for a specified event to occur before returning the time elapsed error The time unit is in milliseconds Returns e Logical identifier of the event actually received e A handle specifying the unique occurrence of an event 3 6 API 53 PyVISA Documentation Release 1 9 dev0 e return value of the library call Return type e eventtype e event e pyvisa constants StatusCode write session data Writes data to device or interface synchronously Corresponds to viWrite function of the VISA library Parameters e session Unique logical identifier to a session e data str data
241. rface or endpoint e length wLength parameter of the setup stage of a USB control transfer This value also specifies the size of the data buffer to receive the data from the optional data stage of the control transfer Returns e The data buffer that receives the data from the optional data stage of the control transfer e return value of the library call 52 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 Return type e bytes e pyvisa constants StatusCode usb_control_out session request_type_bitmap_field request_id request_value index data u Performs a USB control pipe transfer to the device Corresponds to viUsbControlOut function of the VISA library Parameters e session Unique logical identifier to a session e request_type_ bitmap_field bmRequestType parameter of the setup stage of a USB control transfer e request_id bRequest parameter of the setup stage of a USB control transfer e request_value wValue parameter of the setup stage of a USB control transfer e index wIndex parameter of the setup stage of a USB control transfer This is usually the index of the interface or endpoint e data The data buffer that sends the data in the optional data stage of the control transfer Returns return value of the library call Return type pyvisa constants StatusCode vxi_command_query session mode command Sends the device a miscellaneous command or query and or
242. ring that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_MANF_NAME 3221160308 resource _ name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_NAME 3221159938 secondary address VI_ATTR_GPIB_SECONDARY_ADDR specifies the secondary address of the GPIB device used by the given session For the GPIB INTFC Resource this attribute is Read Write 3 6 API 123 PyVISA Documentation Release 1 9 dev0 VISA Attribute VI_ATTR_GPIB_SECONDARY_ADDR 1073676659 Type int Range 0 lt value lt 30 or in 65535 send_command data Write GPIB command bytes on the bus Corresponds to viGpibCommand function of the VISA library Parameters data bytes data tor write Returns Number of written bytes return value of the library call Return type int VISAStatus send_end VIATTR_SEND_END_
243. s 58 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key Access key used by another session with which you want your ses sion to share a lock or None to generate a new shared access key Returns A new shared access key if requested_key is None otherwise same value as the re quested_key lock_context args kwds A context that locks Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key When using default of exclusive the lock is an exclusive lock Otherwise it is the access key for the shared lock or None to generate a new shared access key The returned context is the access_key if applicable lock_excl timeout u default Establish an exclusive lock to the resource Parameters timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout lock_state VIATTR_RSRC_LOCK_STATE indicates the current locking state of the resource The resource can be unlocked locked with an exclusive lock or locked with a shared lock VISA Attribute VI_ATTR_RSRC_LOCK_STATE 1073676
244. s fmt None container lt type list gt Read a list of floating point values from the device Parameters e fmt the format of the values If given it overrides the class attribute values_format Possible values are bitwise disjunctions of the above constants ascii single double and big_endian Default is ascii e container the output datatype Returns the list of read values Return type list register interface_type resource_class resource _class VI_ATTR_RSRC_CLASS specifies the resource class for example INSTR as defined by the canonical resource name VISA Attribute VI_ATTR_RSRC_CLASS 3221159937 resource_info Get the extended information of this resource Parameters resource_name Unique symbolic name of a resource Return type pyvisa highlevel ResourceInfo resource_manufacturer_name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes 96 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_MANF_NAME 3221160308 resource _ name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that
245. s StatusCode 171 error_not_enabled tribute 171 error_not_system_controller pyvisa constants StatusCode attribute 171 error_output_protocol_violation pyvisa constants StatusCode attribute 171 error_queue_error pyvisa constants StatusCode at tribute 171 error_queue_overflow pyvisa constants StatusCode at tribute 171 error_raw_read_protocol_violation pyvisa constants StatusCode attribute 171 error_raw_write_protocol_violation pyvisa constants StatusCode attribute 171 error_resource_busy pyvisa constants StatusCode attribute 171 error_resource_locked pyvisa constants StatusCode at tribute 171 error_resource_not_found pyvisa constants StatusCode attribute 171 error_response_pending pyvisa constants StatusCode at tribute 171 error_serial_framing attribute 171 error_serial_overrun attribute 172 error_serial_parity pyvisa constants StatusCode at tribute 172 error_session_not_locked pyvisa constants StatusCode attribute 172 error_srq_not_occurred pyvisa constants StatusCode at tribute 172 error_system_error tribute 172 error_timeout pyvisa constants StatusCode attribute 172 error_trigger_not_mapped pyvisa constants StatusCode attribute 172 error_user_buffer pyvisa constants StatusCode at tribute 172 error_window_already_mapped pyvisa constants StatusCode attribute 172 error_window_not_mapped pyvisa constants StatusCode attribute 172 exclusive_lock
246. s larger than the default chunk length you should increase its value by saying e g 12 Chapter 2 User guide PyVISA Documentation Release 1 9 dev0 my_instrument chunk_size 102400 This example sets it to 100 kilobytes 2 6 3 Termination characters Somehow the computer must detect when the device is finished with sending a message It does so by using different methods depending on the bus system In most cases you don t need to worry about termination characters because the defaults are very good However if you have trouble you may influence termination characters with PyVISA Termination characters may be one character or a sequence of characters Whenever this character or sequence occurs in the input stream the read operation is terminated and the read message is given to the calling application The next read operation continues with the input stream immediately after the last termination sequence In PyVISA the termination characters are stripped off the message before it is given to you You may set termination characters for each instrument e g my_instrument read_termination r r is carriage return usually appearing in the manuals as CR Alternatively you can give it when creating your instrument object my_instrument rm open_resource GPIB 10 read_termination r The default value depends on the bus system Generally the sequence is empty
247. s to be accessed e open_timeout int Milliseconds before the open operation times out register interface_type resource_class resource class VI_ATTR_RSRC_CLASS specifies the resource class for example INSTR as defined by the canonical resource name VISA Attribute VI_ATTR_RSRC_CLASS 3221159937 154 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 resource_info Get the extended information of this resource Parameters resource_name Unique symbolic name of a resource Return type pyvisa highlevel ResourceInfo resource_manufacturer_name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_MANF_NAME 3221160308 resource _ name VIATTR_RSRC_MANF_NAME is a string that corresponds to the manufacturer name of the vendor that implemented the VISA library This attribute is not related to the device manufacturer attributes Note The value of this attribute is for display purposes only and not for programmatic decisions as the value can differ between VISA implementations and or revisions VISA Attribute VI_ATTR_RSRC_NAME 3221159938
248. s uniquely for an event type Returns user handle a ctypes object interface_number VI_ATTR_INTF_NUM specifies the board number for the given interface VISA Attribute VI_ATTR_INTF_NUM 1073676662 Type int Range 0 lt value lt 65535 interface_type The interface type of the resource as a number 158 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 last_status Last status code for this session Return type pyvisa constants StatusCode lock timeout u default requested_key None Establish a shared lock to the resource Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key Access key used by another session with which you want your ses sion to share a lock or None to generate a new shared access key Returns A new shared access key if requested_key is None otherwise same value as the re quested_key lock_context args kwds A context that locks Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key When using default of exclusive the lock is an exclusive lock Otherwise it is the access key for the shared lock or None to generate a new shared access key The returned context is the access
249. sCode parse_resource_extended session resource_name Parse a resource string to get extended interface information Corresponds to viParseRsrcEx function of the VISA library Parameters e session Resource Manager session should always be the Default Resource Manager for VISA returned from open_default_resource_manager e resource_name Unique symbolic name of a resource Returns Resource information return value of the library call Return type pyvisa highlevel ResourceInfo pyvisa constants StatusCode peek session address width Read an 8 16 or 32 bit value from the specified address Corresponds to viPeek functions of the VISA library Parameters e session Unique logical identifier to a session e address Source address to read the value e width Number of bits to read Returns Data read from bus return value of the library call 46 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 Return type bytes pyvisa constants StatusCode peek_16 session address Read an 16 bit value from the specified address Corresponds to viPeek16 function of the VISA library Parameters e session Unique logical identifier to a session e address Source address to read the value Returns Data read from bus return value of the library call Return type bytes pyvisa constants StatusCode peek_32 session address Read an 32 bit value from the specified address Correspon
250. se 1 9 dev0 e name Attribute for which the state is to be modified Attributes e state The state of the attribute to be set for the specified object source_increment VI ATTR_SRC_INCREMENT is used in the viMoveInXX operations to specify by how many ele ments the source offset is to be incremented after every transfer The default value of this attribute is 1 that is the source address will be incremented by 1 after each transfer and the viMoveInXX operations move from consecutive elements If this attribute is set to 0 the viMoveInXX operations will always read from the same element essentially treating the source as a FIFO register VISA Attribute VI_ATTR_SRC_INCREMENT 1073676352 Type int Range 0 lt value lt 1 spec_version VI_ATTR_RSRC_SPEC_VERSION is the resource version that uniquely identifies the version of the VISA specification to which the implementation is compliant The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version The current VISA specification defines the value to be 00300000h VISA Attribute VI_LATTR_RSRC_SPEC_VERSION 1073676656 Type int Range 0 lt value lt 4294967295 timeout The timeout in milliseconds for all resource I O operations Special values immediate VI_TMO_IMMEDIATE 0 for convenience an
251. send_end VIATTR_SEND_END_EN specifies whether to assert END during the transfer of the last byte of the buffer VISA Attribute VI_ATTR_SEND_END_EN 1073676310 Type bool session Resource session handle Raises pyvisa errors InvalidSession if session is closed set_visa_attribute name state Sets the state of an attribute Parameters e name Attribute for which the state is to be modified Attributes e state The state of the attribute to be set for the specified object source_increment VI ATTR_SRC_INCREMENT is used in the viMoveInXX operations to specify by how many ele ments the source offset is to be incremented after every transfer The default value of this attribute is 1 that is the source address will be incremented by after each transfer and the viMoveInXX operations move from consecutive elements If this attribute is set to 0 the viMoveInXX operations will always read from the same element essentially treating the source as a FIFO register VISA Attribute VI_ATTR_SRC_INCREMENT 1073676352 3 6 API 155 PyVISA Documentation Release 1 9 dev0 Type int Range 0 lt value lt 1 spec_version VI_ATTR_RSRC_SPEC_VERSION is the resource version that uniquely identifies the version of the VISA specification to which the implementation is compliant The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of th
252. separator is comma 2 4 4 Writing binary values To upload a function shape to arbitrary wave generator the command might be WLISt WAVeform DATA lt waveform name gt lt function data gt where lt waveform name gt tells the device under which name to store the data gt gt gt values list range 100 gt gt gt inst write_binary_values WLISt WAVeform DATA somename values Again you can specify the datatype and endianness gt gt gt inst write_binary_values WLISt WAVeform DATA somename values datatype d is_big_endian Fa 2 4 5 Preconfiguring the transfer format Most of the cases each device will transfer data in the same format every time And making the call so detailed everytime can be annoying For this purpose PyVISA provides a way to preconfigure the default Each Message Based Resources exposes an attribute named values_format which is an object with the following properties is_binary datatype is_big_endian container For example to set e g little endian doubles and a numpy array 2 4 Reading and Writing values 9 PyVISA Documentation Release 1 9 dev0 gt gt gt inst values_format is_binary True gt gt gt inst values_format datatype d gt gt gt inst values_format is_big_endian Fals gt gt gt inst values_format container numpy array or shorter gt gt gt inst values_format use_binary d False numpy array
253. shared access key if requested_key is None otherwise same value as the re quested_key lock_context args kwds A context that locks Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key When using default of exclusive the lock is an exclusive lock Otherwise it is the access key for the shared lock or None to generate a new shared access key The returned context is the access_key if applicable lock_excl timeout u default Establish an exclusive lock to the resource Parameters timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout lock_state VIATTR_RSRC_LOCK_STATE indicates the current locking state of the resource The resource can be unlocked locked with an exclusive lock or locked with a shared lock VISA Attribute VI_ATTR_RSRC_LOCK_STATE 1073676292 Type class pyvisa constants AccessModes open access_mode lt AccessModes no_lock 0 gt open_timeout 5000 Opens a session to the specified resource Parameters e access_mode pyvisa constants AccessModes Specifies the mode by which the resource is to be accessed e open_timeout int Milliseconds before the open operation times out query message delay None A combination of writ
254. sms to be dicarded Con stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR VI_ALL_MECH enable_event event_type mechanism context None Enable event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be enabled Con stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR e context Not currently used leave as None encoding Encoding used for read and write operations 100 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 get_visa_attribute name Retrieves the state of an attribute in this resource Parameters name Resource attribute for which the state query is made see Attributes Returns The state of the queried attribute for a specified resource Return type unicode Py2 or str Py3 list or other type ignore_warning warnings_constants Ignoring warnings context manager for the current resource Parameters warnings_constants constants identifying the warnings to ignore implementation_version VI_ATTR_RSRC_IMPL_VERSION is the resource version that uniquely identifies each of the dif ferent revisions or implementations of a resource This attribute value is defined by the individual manufacturer and increments with each new revision The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number o
255. sources VXIInstrument at tribute 155 resource_name pyvisa resources VXIMemory attribute 161 ResourceInfo class in pyvisa highlevel 55 ResourceManager class in pyvisa highlevel 55 rio pyvisa constants InterfaceType attribute 168 attribute attribute attribute attribute Index 189 PyVISA Documentation Release 1 9 dev0 rsnrp pyvisa constants InterfaceType attribute 168 S secondary_address pyvisa resources GPIBInstrument at tribute 123 secondary_address pyvisa resources GPIBInterface at tribute 132 send_command pyvisa resources GPIBInstrument method 124 send_command method 132 send_end 13 send_end pyvisa resources GPIBInstrument attribute 124 send_end pyvisa resources GPIB Interface attribute 132 send_end pyvisa resources SerialInstrument attribute pyvisa resources GPIB Interface 81 send_end pyvisa resources TCPIPInstrument attribute 89 send_end pyvisa resources USBInstrument attribute 106 send_end pyvisa resources VXIInstrument attribute 155 send_ifc pyvisa resources GPIBInstrument method 124 send_ifc pyvisa resources GPIBInterface method 132 serial number pyvisa resources USBInstrument at tribute 106 serial_number pyvisa resources USBRaw attribute 114 SerialInstrument class in pyvisa resources 73 SerialTermination class in pyvisa constants 167 session pyvisa highlevel ResourceManager attribute 56 s
256. specified event in this resource Parameters e in_event_type Logical identifier of the event s to wait for e timeout Absolute time period in time units that the resource shall wait for a specified event to occur before returning the time elapsed error The time unit is in milliseconds None means waiting forever if necessary e capture_timeout When True will not produce a VisalOError VI_ERROR_TMO but instead return a WaitResponse with timed_out True Returns A WaitResponse object that contains event_type context and ret value write message termination None encoding None Write a string message to the device The write_termination is always appended to it Parameters message unicode Py2 or str Py3 the message to be sent Returns number of bytes written 82 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 Return type int write_ascii_values message values converter u f separator u termination None encod ing None Write a string message to the device followed by values in ascii format The write_termination is always appended to it Parameters e message unicode Py2 or str Py3 the message to be sent e values data to be writen to the device e converter callable str function used to convert each value String formatting codes are also accepted Defaults to str e separator a callable that split the str into individual elements I
257. ss session Unmaps memory space previously mapped by map_address Corresponds to viUnmapAddress function of the VISA library Parameters session Unique logical identifier to a session Returns return value of the library call Return type pyvisa constants StatusCode unmap_trigger session trigger_source trigger_destination Undo a previous map from the specified trigger source line to the specified destination line Corresponds to viUnmapTrigger function of the VISA library Parameters e session Unique logical identifier to a session e trigger_source Source line used in previous map Constants VI_TRIG e trigger_destination Destination line used in previous map Con stants VI_TRIG Returns return value of the library call Return type pyvisa constants StatusCode usb_control_in session request_type_bitmap_field request_id request_value index length 0 Performs a USB control pipe transfer from the device Corresponds to viUsbControlIn function of the VISA library Parameters e session Unique logical identifier to a session e request_type bitmap_field bmRequestType parameter of the setup stage of a USB control transfer e request_id bRequest parameter of the setup stage of a USB control transfer e request_value wValue parameter of the setup stage of a USB control transfer e index wIndex parameter of the setup stage of a USB control transfer This is usually the index of the inte
258. ss key Returns A new shared access key if requested_key is None otherwise same value as the re quested_key lock_context args kwds A context that locks Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key When using default of exclusive the lock is an exclusive lock Otherwise it is the access key for the shared lock or None to generate a new shared access key The returned context is the access_key if applicable lock_excl timeout u default Establish an exclusive lock to the resource Parameters timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout lock_state VIATTR_RSRC_LOCK_STATE indicates the current locking state of the resource The resource can be unlocked locked with an exclusive lock or locked with a shared lock VISA Attribute VI_LATTR_RSRC_LOCK_STATE 1073676292 Type class pyvisa constants AccessModes ndac_state This attribute shows the current state of the GPIB NDAC Not Data ACcepted interface line VISA Attribute VI_ATTR_GPIB_NDAC_STATE 1073676386 Type class pyvisa constants LineState open access_mode lt AccessModes no_lock 0 gt open_timeout 5000 Opens a session to the specified resource Parameters access_
259. state The state of the attribute to be set for the specified object 3 6 API 89 PyVISA Documentation Release 1 9 dev0 spec_version VI_ATTR_RSRC_SPEC_VERSION is the resource version that uniquely identifies the version of the VISA specification to which the implementation is compliant The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version The current VISA specification defines the value to be 00300000h VISA Attribute VI_LATTR_RSRC_SPEC_VERSION 1073676656 Type int Range 0 lt value lt 4294967295 stb Service request status register timeout The timeout in milliseconds for all resource I O operations Special values immediate VI_TMO_IMMEDIATE 0 for convenience any value smaller than 1 is considered as 0 infinite VI_TMO_INFINITE float inf for convenience None is considered as float inf To set an infinite timeout you can also use gt gt gt del instrument timeout uninstall_handler event_type handler user_handle None Uninstalls handlers for events in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be uninstalled by a client application e user_handle The user handle ctypes object or None returned by inst
260. string sent from the instrument to the computer In contrast to read no termination characters are stripped Return type bytes read_stb Service request status register read_termination Read termination character read_termination_context args kwds read_values fmt None container lt type list gt Read a list of floating point values from the device Parameters 122 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 e fmt the format of the values If given it overrides the class attribute values_format Possible values are bitwise disjunctions of the above constants ascii single double and big_endian Default is ascii e container the output datatype Returns the list of read values Return type list register interface_type resource_class remote_enabled VI_ATTR_GPIB_REN_STATE returns the current state of the GPIB REN Remote ENable inter face line VISA Attribute VI_ATTR_GPIB_REN_STATE 1073676673 Type class pyvisa constants LineState resource_class VI_ATTR_RSRC_CLASS specifies the resource class for example INSTR as defined by the canonical resource name VISA Attribute VI_LATTR_RSRC_CLASS 3221159937 resource_info Get the extended information of this resource Parameters resource_name Unique symbolic name of a resource Return type pyvisa highlevel ResourceInfo resource_manufacturer_name VIATTR_RSRC_MANF_NAME is a st
261. t Range 0 lt value lt 4294967295 stb Service request status register stop_bits 3 6 API 81 PyVISA Documentation Release 1 9 dev0 VIATTR_ASRL_STOP_BITS is the number of stop bits used to indicate the end of a frame The value VI_ASRL_STOP_ONES indicates one and one half 1 5 stop bits VISA Attribute VI_ATTR_ASRL_STOP_BITS 1073676324 Type class pyvisa constants StopBits timeout The timeout in milliseconds for all resource I O operations Special values immediate VI_TMO_IMMEDTATE 0 for convenience any value smaller than 1 is considered as 0 einfinite VI_TMO_INFINITE float inf for convenience None is considered as float inf To set an infinite timeout you can also use gt gt gt del instrument timeout uninstall_handler event_type handler user_handle None Uninstalls handlers for events in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be uninstalled by a client application e user_handle The user handle ctypes object or None returned by install_handler unlock Relinquishes a lock for the specified resource values_format visa_attributes_classes lt class pyvisa attributes AttrVI_ATTR_RM_SESSION gt lt class pyvisa attributes At wait_on_event in_event_type timeout capture_timeout False Waits for an occurrence of the
262. t currently used leave as None encoding Encoding used for read and write operations get_visa_attribute name Retrieves the state of an attribute in this resource Parameters name Resource attribute for which the state query is made see Attributes 92 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 Returns The state of the queried attribute for a specified resource Return type unicode Py2 or str Py3 list or other type ignore_warning warnings_constants Ignoring warnings context manager for the current resource Parameters warnings_constants constants identifying the warnings to ignore implementation_version VIATTR_RSRC_IMPL_VERSION is the resource version that uniquely identifies each of the dif ferent revisions or implementations of a resource This attribute value is defined by the individual manufacturer and increments with each new revision The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version VISA Attribute VI_ATTR_RSRC_IMPL_VERSION 1073676291 Type int Range 0 lt value lt 4294967295 install_handler event_type handler user_handle None Installs handlers for event callbacks in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be instal
263. te 170 error_machine_not_available pyvisa constants StatusCode attribute 170 error_memory_not_shared pyvisa constants StatusCode attribute 170 error_no_listeners pyvisa constants StatusCode at tribute 170 error_no_permission attribute 170 error_nonimplemented_operation pyvisa constants StatusCode attribute 170 error_nonsupported_attribute pyvisa constants StatusCode attribute 170 error_nonsupported_attribute_state pyvisa constants StatusCode attribute 170 error_nonsupported_format pyvisa constants StatusCode attribute 170 error_nonsupported_interrupt pyvisa constants StatusCode attribute 170 error_nonsupported_line pyvisa constants StatusCode attribute 171 error_nonsupported_mechanism pyvisa constants StatusCode attribute 171 error_nonsupported_mode pyvisa constants StatusCode attribute 171 error_nonsupported_offset pyvisa constants StatusCode attribute 171 error_nonsupported_offset_alignment pyvisa constants StatusCode attribute 171 error_nonsupported_operation pyvisa constants StatusCode attribute 171 pyvisa constants StatusCode at pyvisa constants StatusCode pyvisa constants StatusCode at pyvisa constants StatusCode 180 Index PyVISA Documentation Release 1 9 dev0 error_nonsupported_varying_ widths pyvisa constants StatusCode attribute 171 error_nonsupported_width pyvisa constants StatusCode attribute 171 error_not_cic pyvisa constant
264. ter callable function used to convert each element Defaults to float e separator a callable that split the str into individual elements If a str is given data split separator is used e container container type to use for the output data Type separator str gt collections Iterable int str Returns the answer from the device Return type list query binary values message datatype u f is_big_endian False container lt type list gt de lay None header_fmt u ieee Converts an iterable of numbers into a block of data in the ieee format Parameters e message the message to send to the instrument e datatype the format string for a single element See struct module e is_big_endian boolean indicating endianess Defaults to False e container container type to use for the output data e delay delay in seconds between write and read operations if None defaults to self query_delay Return type bytes query delay 0 0 64 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 query_values message delay None Query the device for values returning an iterable of values The datatype expected is obtained from values_format Parameters e message str the message to send e delay delay in seconds between write and read operations if None defaults to self query_delay Returns the answer from the device Return type list read termination None encod
265. the library call Return type session opyvvisa constants StatusCode out_16 session space offset data extended False Write in an 16 bit value from the specified memory space and offset Corresponds to viOut16 functions of the VISA library Parameters e session Unique logical identifier to a session e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e data Data to write to bus e extended Use 64 bits offset independent of the platform Returns return value of the library call Return type pyvisa constants StatusCode out_32 session space offset data extended False Write in an 32 bit value from the specified memory space and offset Corresponds to viOut32 functions of the VISA library Parameters e session Unique logical identifier to a session e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e data Data to write to bus e extended Use 64 bits offset independent of the platform Returns return value of the library call Return type pyvisa constants StatusCode out_64 session space offset data extended False Write in an 64 bit value from the specified memory space and offset Corresponds to viOut64 functions of the VISA library Parameters e session Unique logical identifier to a session e space Specifi
266. tn_state pyvisa resources GPIBInterface attribute 127 B baud_rate pyvisa resources SerialInstrument attribute 74 before_close pyvisa resources FirewireInstrument method 133 before_close pyvisa resources GPIB Instrument method 117 before_close pyvisa resources GPIBInterface method 127 before_close pyvisa resources MessageBasedResource method 61 before_close pyvisa resources PXIInstrument method 139 before_close pyvisa resources PXIMemory method 145 before_close pyvisa resources RegisterBasedResource method 68 before_close pyvisa resources Resource method 57 before_close pyvisa resources SerialInstrument method 74 before_close pyvisa resources TCPIPInstrument method 84 before_close pyvisa resources TCPIPSocket method 92 before_close method 99 before_close pyvisa resources USBRaw method 109 before_close pyvisa resources VXIBackplane method 163 before_close method 151 before_close pyvisa resources VXIMemory method 157 break_length pyvisa resources SerialInstrument tribute 74 break_state pyvisa resources SerialInstrument attribute 74 buffer_read method 33 pyvisa resources USBInstrument pyvisa resources VXIInstrument at pyvisa highlevel VisaLibrary Base 177 PyVISA Documentation Release 1 9 dev0 buffer_write method 33 bytes_in_buffer pyvisa resources Seriallnstrument at tribute 75
267. to be written Returns Number of bytes actually transferred return value of the library call Return type int pyvisa constants StatusCode write_asynchronous Ly session data Writes data to device or interface asynchronously Corresponds to viWriteAsync function of the VISA library Parameters e session Unique logical identifier to a session e data data to be written Returns Job ID of this asynchronous write operation return value of the library call Return type jobid pyvisa constants StatusCode write_from_file session filename count Take data from a file and write it out synchronously Corresponds to viWriteFromFile function of the VISA library Parameters e session Unique logical identifier to a session e filename Name of file from which data will be read e count Number of bytes to be written Returns Number of bytes actually transferred return value of the library call Return type int pyvisa constants StatusCode write_memory session space offset data width extended False Write in an 8 bit 16 bit 32 bit value to the specified memory space and offset Corresponds to viOut functions of the VISA library Parameters e session Unique logical identifier to a session e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read 54 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 e
268. tribute VI_ATTR_ASRL_BREAK_STATE 1073676732 Type class pyvisa constants LineState bytes_in buffer VIATTR_ASRL_AVAIL_NUM shows the number of bytes available in the low level I O receive buffer VISA Attribute VI_ATTR_ASRL_AVAIL_NUM 1073676460 Type int Range 0 lt value lt 4294967295 chunk_size 20480 clear Clears this resource close Closes the VISA session and marks the handle as invalid data_bits VI_ATTR_ASRL_DATA BITS is the number of data bits contained in each frame from 5 to 8 The data bits for each frame are located in the low order bits of every byte stored in memory VISA Attribute VI_ATTR_ASRL_DATA_ BITS 1073676322 Type int Range 5 lt value lt 8 disable_event event_type mechanism Disables notification of the specified event type s via the specified mechanism s Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be disabled stants VI_QUEUE VI_HNDLR VI_SUSPEND_HNDLR VI_ALL_MECH discard_events event_type mechanism Discards event occurrences for specified event types and mechanisms in this resource Parameters e event_type Logical event identifier e mechanism Specifies event handling mechanisms to be dicarded stants VI_QUEUE VI_LHNDLR VI_SUSPEND_HNDLR VI_ALL_MECH discard_null Con Con 3 6 API 75 PyVISA Documentation Release 1 9 dev0 If set to V
269. ttribute VI_ATTR_4882_COMPLIANT 1073676703 Type bool last_status Last status code for this session Return type pyvisa constants StatusCode lock timeout u default requested_key None Establish a shared lock to the resource Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key Access key used by another session with which you want your ses sion to share a lock or None to generate a new shared access key Returns A new shared access key if requested_key is None otherwise same value as the re quested_key lock_context args kwds A context that locks Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key When using default of exclusive the lock is an exclusive lock Otherwise it is the access key for the shared lock or None to generate a new shared access key The returned context is the access_key if applicable lock_excl timeout u default Establish an exclusive lock to the resource Parameters timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout lock_state VIATTR_RSRC_LOCK_STATE indicates the current locking
270. u can choose normal or high speed HS 488 transfers In serial TCPIP or USB RAW you can choose normal transfers or 488 2 defined strings In USB INSTR you can choose normal or vendor specific transfers VISA Attribute VI_ATTR_IO_PROT 1073676316 Type int Range 0 lt value lt 65535 is_4882_ compliant VIATTR_4882_COMPLIANT specifies whether the device is 488 2 compliant VISA Attribute VI_ATTR_4882_COMPLIANT 1073676703 Type bool last_status Last status code for this session Return type pyvisa constants StatusCode lock timeout u default requested_key None Establish a shared lock to the resource Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key Access key used by another session with which you want your ses sion to share a lock or None to generate a new shared access key Returns A new shared access key if requested_key is None otherwise same value as the re quested_key lock_context args kwds A context that locks Parameters e timeout Absolute time period in milliseconds that a resource waits to get unlocked by the locking session before returning an error Defaults to self timeout e requested_key When using default of exclusive the lock is an exclusive lock Otherwise it is the access key for the shared lock or None to generate a new shared
271. ues_format visa_attributes_classes lt class pyvisa attributes AttrVI_ATTR_RM_SESSION gt lt class pyvisa attributes At wait_on_event in_event_type timeout capture_timeout False Waits for an occurrence of the specified event in this resource Parameters e in_event_type Logical identifier of the event s to wait for e timeout Absolute time period in time units that the resource shall wait for a specified event to occur before returning the time elapsed error The time unit is in milliseconds None means waiting forever if necessary e capture_timeout When True will not produce a VisalOError VI_ERROR_TMO but instead return a WaitResponse with timed_out True Returns A WaitResponse object that contains event_type context and ret value write message termination None encoding None Write a string message to the device The write_termination is always appended to it Parameters message unicode Py2 or str Py3 the message to be sent Returns number of bytes written Return type int write_ascii_values message values converter u f separator u termination None encod ing None Write a string message to the device followed by values in ascii format The write_termination is always appended to it 3 6 API 67 PyVISA Documentation Release 1 9 dev0 Parameters e message unicode Py2 or str Py3 the message to be sent e values data to be writen to the device
272. unction 1 12 1 INSTR PXI0 MEMACC PXI MEMACC session TCPIP dev company comTUPslPRrdevice using VXI 11 or LXI located at the specified address This uses the default LAN Device Name of inst0 TCPIPO 1 2 3 4 9997 FOGKKIP IP access to port 999 at the specified IP address USB 0x1234 125 A 22 USB Test amp Measurement class device with manufacturer ID 0x1234 model code 125 Si INSTR and serial number A22 5 This uses the device s first available USBTMC interface This is usually number 0 USB 0x5678 0x33 5 NO8Aw LURBANDnclass device with manufacturer ID 0x5678 model code 0x33 and serial number SN999 This uses the device s interface number 1 visa hostname ASRIL ITAN amp BBurce ASRL1 INSTR on the specified remote system VXI 1 BACKPLANE Mainframe resource for chassis 1 on the default VXI system which is interface 0 VXI MEMACC Board level register access to the VXI interface VXI0 1 INSTR A VXI device at logical address 1 in VXI interface VXIO VXI0 SERVANT Servant device side resource for VXI interface 0 3 2 Migrating from PyVISA lt 1 5 Note if you want PyVISA 1 4 compatibility use PyVISA 1 5 that provides Python 3 support better visa library detection heuristics Windows Linux and OS X support and no singleton object PyVISA 1 6 introduces a few compatibility breaks Some of these decisions were inspired by the visalib package as a part of Lantz
273. unlock pyvisa resources Resource method 61 unlock pyvisa resources SerialInstrument method 82 unlock pyvisa resources TCPIPInstrument method 90 unlock pyvisa resources TCPIPSocket method 98 unlock pyvisa resources USBInstrument method 107 unlock pyvisa resources USBRaw method 115 unlock pyvisa resources V XIBackplane method 166 unlock pyvisa resources VXIInstrument method 156 unlock pyvisa resources VXIMemory method 162 unmap_address pyvisa highlevel VisaLibrary Base method 52 unmap_trigger method 52 usb pyvisa constants InterfaceType attribute 168 usb_control_in pyvisa highlevel VisaLibrary Base method 52 usb_control_out method 53 usb_control_out method 107 usb_protocol pyvisa resources USBInstrument attribute 107 usb_protocol pyvisa resources USBRaw attribute 115 pyvisa highlevel VisaLibrary Base pyvisa highlevel VisaLibrary Base pyvisa resources USBInstrument visa_attributes_classes pyvisa resources FirewireInstrument attribute 138 visa_attributes_classes pyvisa resources GPIBInstrument attribute 125 visa_attributes_classes attribute 133 pyvisa resources GPIBInterface visa_attributes_classes pyvisa resources MessageBasedResource attribute 67 visa_attributes_classes pyvisa resources PXIInstrument attribute 144 visa_attributes_classes pyvisa resources PXIMemory at tribute 150 visa_attributes_classes pyvisa reso
274. urce shall wait for a specified event to occur before returning the time elapsed error The time unit is in milliseconds None means waiting forever if necessary e capture_timeout When True will not produce a VisalOError VI_LERROR_TMO but instead return a WaitResponse with timed_out True Returns A WaitResponse object that contains event_type context and ret value 156 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 class pyvisa resources VXIMemory resource_manager resource_name Communicates with to devices of type VXI board MEMACC More complex resource names can be specified with the following grammar VXI board MEMACC Do not instantiate directly use pyvisa highlevel ResourceManager open_resource allow_dma This attribute specifies whether I O accesses should use DMA VI_TRUE or Programmed I O VI_FALSE In some implementations this attribute may have global effects even though it is documented to be a local attribute Since this affects performance and not functionality that behavior is acceptable VISA Attribute VI_ATTR_DMA_ALLOW_EN 1073676318 Type bool before_close Called just before closing an instrument clear Clears this resource close Closes the VISA session and marks the handle as invalid destination_increment VIL ATTR_DEST_INCREMENT is used in the viMoveOutXX operations to specify by how many elements the destination offset is to be incremented after ev
275. urces RegisterBasedResource attribute 73 visa_attributes_classes attribute 61 visa_attributes_classes pyvisa resources SerialInstrument attribute 82 visa_attributes_classes pyvisa resources TCPIPInstrument attribute 90 visa_attributes_classes attribute 98 visa_attributes_classes pyvisa resources USBInstrument attribute 107 visa_attributes_classes attribute 116 visa_attributes_classes pyvisa resources VXIBackplane attribute 166 visa_attributes_classes pyvisa resources VXIInstrument attribute 156 visa_attributes_classes pyvisa resources VXIMemory at tribute 162 VisaLibraryBase class in pyvisa highlevel 32 vxi pyvisa constants InterfaceType attribute 168 pyvisa resources Resource pyvisa resources TCPIPSocket pyvisa resources USBRaw 192 Index PyVISA Documentation Release 1 9 dev0 vxi_command_query pyvisa highlevel VisaLibraryBase method 53 VXIBackplane class in pyvisa resources 162 VXInstrument class in pyvisa resources 151 VXIMemory class in pyvisa resources 157 W wait_for_srq pyvisa resources GPIBInstrument method 125 wait_on_event pyvisa highlevel VisaLibrary Base method 53 wait_on_event pyvisa resources FirewireInstrument method 138 wait_on_event pyvisa resources GPIBInstrument method 125 wait_on_event method 133 wait_on_event pyvisa resources MessageBasedResource method 67 wait_on_event meth
276. us return value of the library call Return type list oyvisa constants StatusCode move_in_32 session space offset length extended False Moves an 32 bit block of data from the specified address space and offset to local memory Corresponds to viMoveln32 functions of the VISA library Parameters e session Unique logical identifier to a session e space Specifies the address space Constants SPACE 3 6 API 41 PyVISA Documentation Release 1 9 dev0 e offset Offset in bytes of the address or register from which to read e length Number of elements to transfer where the data width of the elements to transfer is identical to the source data width e extended Use 64 bits offset independent of the platform Returns Data read from the bus return value of the library call Return type list oyvisa constants StatusCode move_in_64 session space offset length extended False Moves an 64 bit block of data from the specified address space and offset to local memory Corresponds to viMoveln64 functions of the VISA library Parameters e session Unique logical identifier to a session e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e length Number of elements to transfer where the data width of the elements to transfer is identical to the source data width e extended Use 64 bits offset independent
277. usID value error_nonsupported_line None The specified trigger source line trigSrc or destination line trigDest is not supported by this VISA implementation or the combination of lines is not a valid mapping error_nonsupported_mechanism None The specified mechanism is not supported for the specified event type error_nonsupported_mode None The specified mode is not supported by this VISA implementation error_nonsupported_offset None Specified offset is not accessible from this hardware error_nonsupported_offset_alignment None The specified offset is not properly aligned for the access width of the operation error_nonsupported_operation None The session or object reference does not support this operation error_nonsupported_ varying widths None Cannot support source and destination widths that are different error_nonsupported_width None Specified width is not supported by this hardware error_not_cic None The interface associated with this session is not currently the Controller in Charge error_not_enabled None The session must be enabled for events of the specified type in order to receive them error_not_system_controller None The interface associated with this session is not the system controller error_output_protocol_violation None Device reported an output protocol error during transfer error_queue_error None Unable to queue asynchronous operation error_queue_overflow None Th
278. use 60 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 gt gt gt del instrument timeout uninstall_handler event_type handler user_handle None Uninstalls handlers for events in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be uninstalled by a client application e user_handle The user handle ctypes object or None returned by install_handler unlock Relinquishes a lock for the specified resource visa_attributes_classes lt class pyvisa attributes AttrVI_ATTR_RM_SESSION gt lt class pyvisa attributes At wait_on_event in_event_type timeout capture_timeout False Waits for an occurrence of the specified event in this resource Parameters e in_event_type Logical identifier of the event s to wait for e timeout Absolute time period in time units that the resource shall wait for a specified event to occur before returning the time elapsed error The time unit is in milliseconds None means waiting forever if necessary e capture_timeout When True will not produce a VisalOError VI_ERROR_TMO but instead return a WaitResponse with timed_out True Returns A WaitResponse object that contains event_type context and ret value class pyvisa resources MessageBasedResource args kwargs Base class for resources that use message based communication CR w r
279. usive lock or locked with a shared lock VISA Attribute VI_LATTR_RSRC_LOCK_STATE 1073676292 Type class pyvisa constants AccessModes 70 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 move_in space offset length width extended False Moves a block of data to local memory from the specified address space and offset Parameters e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read length Number of elements to transfer where the data width of the elements to transfer is identical to the source data width width Number of bits to read per element extended Use 64 bits offset independent of the platform move_out space offset length data width extended False Moves a block of data from local memory to the specified address space and offset Parameters e space Specifies the address space Constants SPACE offset Offset in bytes of the address or register from which to read length Number of elements to transfer where the data width of the elements to transfer is identical to the source data width data Data to write to bus width Number of bits to read per element extended Use 64 bits offset independent of the platform open access_mode lt AccessModes no_lock 0 gt open_timeout 5000 Opens a session to the specified resource Parameters e
280. vices matching query Parameters query regular expression used to match devices list_resources_info query u INSTR Returns a dictionary mapping resource names to resource extended information of all connected devices matching query Parameters query regular expression used to match devices Returns Mapping of resource name to ResourceInfo Return type dict str ovvisa highlevel ResourceInfo open_bare_resource resource_name access_mode lt AccessModes no_lock 0 gt open_timeout 0 Open the specified resource without wrapping into a class Parameters 3 6 API 55 PyVISA Documentation Release 1 9 dev0 e resource_name name or alias of the resource to open e access_mode pyvisa constants AccessModes access mode e open_timeout time out to open Returns Unique logical identifier reference to a session open_resource resource_name access_mode lt AccessModes no_lock 0 gt open_timeout 0 re source_pyclass None kwargs Return an instrument for the resource name Parameters e resource_name name or alias of the resource to open e access_mode pyvisa constants AccessModes access mode e open_timeout time out to open e resource_pyclass resource python class to use to instantiate the Resource De faults to None select based on the resource name e kwargs keyword arguments to be used to change instrument attributes after construc tion Return type pyvisa
281. visa_attributes_classes lt class pyvisa attributes AttrVI_ATTR_RM_SESSION gt lt class pyvisa attributes At wait_on_event in_event_type timeout capture_timeout False Waits for an occurrence of the specified event in this resource Parameters e in_event_type Logical identifier of the event s to wait for e timeout Absolute time period in time units that the resource shall wait for a specified event to occur before returning the time elapsed error The time unit is in milliseconds None means waiting forever if necessary e capture_timeout When True will not produce a VisalOError VI_ERROR_TMO but instead return a WaitResponse with timed_out True Returns A WaitResponse object that contains event_type context and ret value write_memory space offset data width extended False Write in an 8 bit 16 bit 32 bit value to the specified memory space and offset Parameters 150 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 e space Specifies the address space Constants SPACE e offset Offset in bytes of the address or register from which to read e data Data to write to bus e width Number of bits to read e extended Use 64 bits offset independent of the platform Corresponds to viOut functions of the visa library class pyvisa resources VXIInstrument resource_manager resource_name Communicates with to devices of type VXI VXI logical address
282. warnings to ignore implementation_version VI_ATTR_RSRC_IMPL_VERSION is the resource version that uniquely identifies each of the dif ferent revisions or implementations of a resource This attribute value is defined by the individual manufacturer and increments with each new revision The format of the value has the upper 12 bits as the major number of the version the next lower 12 bits as the minor number of the version and the lowest 8 bits as the sub minor number of the version VISA Attribute VI_ATTR_RSRC_IMPL_VERSION 1073676291 Type int Range 0 lt value lt 4294967295 install_handler event_type handler user_handle None Installs handlers for event callbacks in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be installed by a client appli cation e user_handle A value specified by an application that can be used for identifying handlers uniquely for an event type Returns user handle a ctypes object interface_number VI_ATTR_INTF_NUM specifies the board number for the given interface VISA Attribute VI_ATTR_INTF_NUM 1073676662 Type int Range 0 lt value lt 65535 interface_type The interface type of the resource as a number last_status Last status code for this session Return type pyvisa constants StatusCode lock timeout u default requested_key None Establish a shared lock to the resource Parameter
283. write and read operations you can do both with one query call Thus the above source code is equivalent to print itc4 query V It couldn t be simpler 2 4 Reading and Writing values Some instruments allow to transfer to and from the computer larger datasets with a single query A typical example is an oscilloscope which you can query for the whole voltage trace Or an arbitrary wave generator to which you have to transfer the function you want to generate Basically data like this can be transferred in two ways in ASCII form slow but human readable and binary fast but more difficult to debug PyVISA Message Based Resources have two different methods for this called pyvisa resources MessageBasedResource query_ascii_values and pyvisa resources MessageBasedResource query_binary_values It also has the convenient pyvisa resources MessageBasedResource query_values which will use follow a previously established configuration 2 4 1 Reading ASCII values If your oscilloscope open in the variable inst has been configured to transfer data in ASCII when the CURV command is issued you can just query the values like this gt gt gt values inst query_ascii_values CURV values will be 1ist containing the values from the device In many cases you do not want a 1ist but rather a different container type such as a numpy array You can of course cast the data afterwards like this
284. www ni com pdf manuals 370423a pdf 3 1 1 VISA Resource Syntax and Examples This is adapted from the VISA manual The following table shows the grammar for the address string Optional string segments are shown in square brackets D 21 PyVISA Documentation Release 1 9 dev0 Interface Syntax ENET Serial ASRL 0 host address serial port INSTR INSTR GPIB INSTR GPIB board primary address secondary address INSTR GPIB INTFC GPIB board INTFC PXI BACKPLANE PXI interface chassis number BACKPLANE PXI INSTR PX bus device function INSTR PXI INSTR PX interface bus device function INSTR PXI INSTR PX interface CHASSISchassis number SLOTslot number FUNCfunction INSTR PXI MEMACC PX interface MEMACC Remote NI VISA visa host address server port remote resource Serial INSTR ASRLboard INSTR TCPIP INSTR TCPIP board host address LAN device name INSTR TCPIP SOCKET TCPIP board host address port SOCKET USB INSTR USB board manufacturer ID model code serial number USB interface number INSTR USB RAW USB board manufacturer ID model code serial number USB interface number RAW VXI BACKPLANE VXI board VXI logical address BACKPLANE VXI INSTR VXI board VXI logical address INSTR VXI MEMACC VXI board MEMACC VXI SERVANT VXI board SERVANT Use the GPIB
285. x PyVISA Documentation Release 1 9 dev0 install_handler pyvisa resources SerialInstrument method 77 install_handler pyvisa resources TCPIPInstrument method 85 install_handler pyvisa resources TCPIPSocket method 93 install_handler method 101 install_handler pyvisa resources USBRaw method 110 install_handler method 164 install_handler method 152 install_handler method 158 install_visa_handler pyvisa highlevel VisaLibraryBase method 38 interface_number pyvisa resources FirewireInstrument attribute 135 interface_number pyvisa resources GPIBInstrument at tribute 119 interface_number attribute 129 pyvisa resources USBInstrument pyvisa resources VXIBackplane pyvisa resources V XIInstrument pyvisa resources VXIMemory pyvisa resources GPIBInterface interface_type pyvisa resources GPIBInterface at tribute 129 interface_type pyvisa resources MessageBasedResource attribute 63 interface_type pyvisa resources PXIInstrument at tribute 141 interface_type pyvisa resources PXIMemory attribute 147 interface_type pyvisa resources RegisterBasedResource attribute 70 interface_type pyvisa resources Resource attribute 58 interface_type pyvisa resources Seriallnstrument at tribute 77 interface_type pyvisa resources TCPIPInstrument attribute 86 interface_type pyvisa resources TCPIPSocket attribute 93 interface_type pyvis
286. y value smaller than 1 is considered as 0 einfinite VI_TMO_ INFINITE float inf for convenience None is considered as float inf To set an infinite timeout you can also use gt gt gt del instrument timeout uninstall_handler event_type handler user_handle None Uninstalls handlers for events in this resource Parameters e event_type Logical event identifier e handler Interpreted as a valid reference to a handler to be uninstalled by a client application e user_handle The user handle ctypes object or None returned by install_handler unlock Relinquishes a lock for the specified resource visa_attributes_classes lt class pyvisa attributes AttrVI_ATTR_RM_SESSION gt lt class pyvisa attributes At 144 Chapter 3 More information PyVISA Documentation Release 1 9 dev0 wait_on_event in_event_type timeout capture_timeout False Waits for an occurrence of the specified event in this resource Parameters e in_event_type Logical identifier of the event s to wait for e timeout Absolute time period in time units that the resource shall wait for a specified event to occur before returning the time elapsed error The time unit is in milliseconds None means waiting forever if necessary e capture_timeout When True will not produce a VisalOError VI_ERROR_TMO but instead return a WaitResponse with timed_out True Returns A WaitResponse obj
287. y3 the message to be sent Returns number of bytes written Return type int write_ascii_values message values converter u f separator u termination None encod ing None Write a string message to the device followed by values in ascii format The write_termination is always appended to it Parameters e message unicode Py2 or str Py3 the message to be sent e values data to be writen to the device e converter callable str function used to convert each value String formatting codes are also accepted Defaults to str e separator a callable that split the str into individual elements If a str is given data split separator is used Type separator collections Iterable T gt str str Returns number of bytes written Return type int write_binary values message values datatype u f is_big_endian False termination None encoding None Write a string message to the device followed by values in binary format The write_termination is always appended to it Parameters e message unicode Py2 or str Py3 the message to be sent e values data to be writen to the device e datatype the format string for a single element See struct module e is_big_endian boolean indicating endianess Returns number of bytes written Return type int write_raw message Write a byte message to the device Parameters message bytes the message to be sent Returns
288. yVISA Documentation Release 1 9 dev0 def move_out_16 self session space offset length data xtended False def move_out_32 self session space offset length data xtended False def move_out_64 self session space offset length data xtended False def open self session resource_name def open_default_resource_manager self def out_8 self session space offset data xtended False def out_16 self session space offset data xtended False def out_32 self session space offset data xtended False def out_64 self session space offset data xtended False def parse_resource self session resource_name def parse_resource_extended self session resource_name def peek_8 self session address def peek_16 self session address def peek_32 self session address def peek_64 self session address def poke_8 self session address data def poke_16 self session address data def poke_32 self session address data def poke_64 self session address data def read self session count def read_asynchronously self session count def read_stb self session def read_to_file self session filename count def set_attribute self session attribute attribute_state def set_buffer self session mask size def status_description self session status def terminate self session degree job_id def uninstall_handler self session event_type ha
289. you might want to read Migrating from PyVISA lt 1 5 2 3 1 An example Let s go in medias res and have a look at a simple example 6 Chapter 2 User guide PyVISA Documentation Release 1 9 dev0 gt gt gt import visa gt gt gt rm visa ResourceManager gt gt gt rm list_resources ASRL1 INSTR ASRL2 INSTR GPIBO 14 INSTR gt gt gt my_instrument rm open_resource GPIBO 14 INSTR gt gt gt print my_instrument query IDN This example already shows the two main design goals of PyVISA preferring simplicity over generality and doing it the object oriented way After importing visa we create a ResourceManager object If called without arguments PyVISA will use the default backend NI which tries to find the VISA shared library for you You can check the location of the shared library used simply by gt gt gt print rm lt ResourceManager path to visa so gt Note In some cases PyVISA is not able to find the library for you resulting in an OSError To fix it find the library path yourself and pass it to the ResourceManager constructor You can also specify it in a configuration file as discussed in Configuring the NI backend Once that you have a ResourceManager you can list the available resources using the list_resources method The output is a tuple listing the VISA resource names In this case there is a GPIB i

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