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Quad Digital Voltmeter - Stanford Research Systems

1. Parameters shown in and are not always required Parameters in are required to set a value and should be omitted for queries Parameters in are optional in both set and query commands Pa rameters listed without surrounding characters are always required Do not send or or as part of the command Multiple parameters are separated by commas Multiple commands may be sent on one command line by separating them with semi colons so long as the input buffer does not overflow Commands are terminated by either CR or LF characters Null commands and whitespaces are ignored Execution of the command does not begin until the command terminator is received Token parameters generically shown as Z in the command descrip tions can be specified either as a keyword or as an integer value Command descriptions list the valid keyword options with each keyword followed by its corresponding integer value For example to set the response termination sequence to CR LF the following two commands are equivalent TERM CRLF or TERM 3 For queries that return token values the return format keyword or integer is specified with the TOKN command SIM970 Quad Digital Voltmeter SRS 3 8 Remote Operation 3 4 2 Notation The following table summarizes the notation used in the command descriptions Symbol Definition Bit number 0 7 Unsigned integer Channel number 1 4 n
2. TRIP n Overvoltage Trip Clear query the overvoltage trip status of Channel n SOUT Stop Streaming Turn off the continuous output of multiple VOLT responses SIM970 Quad Digital Voltmeter SRS Remote Operation MESG n s Display Message 3 4 5 Display a text message on Channel n or clear the message if s is not specified The message is overwritten by the next reading display unless DISX n OFF is set The message parameter s is given without special quotation marks but is subject to the following formatting rules e Sis case insensitive e The first character of s must be either _ 1 or I e Use the _ character to specify a blank space e Valid display characters are the digits 0123456789 the letters ABCDEFGHIJLNOPQRSTUYZ and the and marks The letters K M V W and X are not displayable and will appear as blanks Letters may be displayed in lowercase or in uppercase Note that the leading indicator cannot be illuminated with the MESG command this allows the user to easily distinguish reading results from remote messages Configuration commands For configuration commands that accept a channel number n setting n 0 selects all four channels Replies to commands that query all four channels are separated by commas LOCL Local Interface Set the SIM970 into local mode All channels are placed into one of the four Range settings Table 2 1 and triggers are set to LOCAL
3. PARI z Parity Set query the parity to z NONE 0 ODD 1 EVEN 2 MARK 3 SPACE 4 SIM970 Quad Digital Voltmeter SRS 3 18 Remote Operation 3 5 Status Model status registers The SIM970 status registersfollow the hierarchical IEEE 488 2 format A block diagram of the status register array is given in Figure 3 1 There are two categories of registers in the SIM970 status model Event Registers Enable Registers These read only registers record the occurrence of defined events If the event occurs the corresponding bit is set to 1 Upon querying an event register all set bits within it are cleared These are sometimes known as sticky bits since once set a bit can only be cleared by reading its value Event register names end with SR These read write registers define a bitwise mask for their cor responding event register If a bit position is set in an event register while the same bit position is also set in the enable register then the corresponding summary bit message is set Enable register names end with SE Communication Error Status DCAS Device Clear CESR CESE Standard Event Status Status Byte ESR ESE Channel Status Trip2 Channel 2 uga Trip1 Channel 1 o CHSR CHSE Figure 3 1 Status register model for the SIM970 Quad Digital Volt meter ASRS SIM970 Quad Digital Voltmeter 3 5 Status Model 3 5 1 Stat
4. j Channel Status Enable Set query the Channel Status Enable Register bit i to j PSTA z Pulse STATUS Mode Set query the Pulse STATUS mode to z OFF 0 ON 1 When PSTA ON is set all new service requests will only pulse the STATUS signal LOW for a minimum of 1 us The default behavior is to latch STATUS LOW until a STB query is received LBTN Last Button Query the number of the last button pressed The response is 1 2 3 or 4 based on which channel s button was last pressed 0 is returned if no button was pressed since the last LBTN 3 4 8 Interface commands The Interface commands provide control over the interface between the SIM970 and the host computer ASRS SIM970 Quad Digital Voltmeter 3 4 Commands RST Reset Reset the SIM970 to its default configuration The effects of RST are a subset of what happens during power on RST sets the following e All four channels to Range 1 autoranging ALL The display and the front panel buttons to ON The trigger mode to LOCAL The trigger count TCNT and the remaining trigger count TREM to 1 e The trigger period TPER to 1000 ms e The token mode to OFF e One LOCAL trigger is issued immediately After RST autoranging may quickly bring the SIM970 into a Range other than Range 1 The reset does not attempt to clear the overload trip state of a channel IDN Identify Query the devi
5. 0 means all Character string Literal token Required for queries illegal for set commands Parameter always required Required parameter for set commands illegal for queries Optional parameter for both set and query forms ASRS SIM970 Quad Digital Voltmeter 3 4 Commands 3 9 3 4 3 General commands HELP Instrument Help Outputs a condensed version of Section 3 4 to the remote interface HELP may be used with or without the query sign with the same effects 3 4 4 Measure commands For measure commands that accept a channel number n setting n 0 selects all four channels Replies to commands that query all four channels are separated by commas VOLT n j Measured Voltage Query the voltage for Channel n If j is specified it denotes the number of successive readings to return VOLT n 1 is equivalent to VOLT n If j 0 is specified then readings are returned continuously until the SOUT command is sent The maximum j 65535 The first value is returned immediately following the query this value is the last known measured voltage corrected for the offset and gain errors Subsequent readings are sent to the remote interface when autocalibration sequences on the particular channel complete Section 2 1 3 VGND n Measured Ground Query the ground voltage offset correction for Channel n VREF n Measured Reference Query the 5 V reference voltage gain correction for Channel n
6. real voltage offset where offset 0 gainerror The gain errorresults in the voltage reading multiplied by some fac SRS SIM970 Quad Digital Voltmeter 2 1 Operating Modes tor compared to the true value voltage read by the instrument real voltage gain where gain 1 Most of the gain error is caused by resistance drift in the input atten uator Some of it is due to gain errors in the circuitry that follows the input attenuator and to errors in the converter Four autocalibration regimes are possible Autocalibration Error corrected How often For other settings NONE Offset Once Every combination Gain Once Attenuator ON Gain Never Attenuator OFF or OUT GND Offset Continuously Every combination Gain Once Attenuator ON Gain Never Attenuator OFF or OUT GNDREF3 Offset Continuously Every combination Gain Continuously Every combination GNDREF4 Offset Continuously Every combination Gain Continuously Every combination Autocalibration is performed by the instrument by taking alternat ing readings of the input voltage the internal ground and the inter nal reference the ground and reference readings are taken as these voltages pass through the same signal path as the input voltage Therefore it is possible to calibrate the input attenuator and subse quent circuitry by comparing the attenuated reference signal with the original The sequence of readings for each of the
7. z PSTA z 3 17 Parity 3 14 Pulse STATUS Mode S SCAL n 1 j SOUT 3 11 Display Scale 3 9 Stop Streaming T 3 12 Trigger Count 3 17 Response Termination 3 12 Trigger Mode 3 17 Token Mode 3 13 Trigger Period 3 12 Trigger Count Remaining 3 9 Overvoltage Trip VGND n VOLT nL j VREF n Measured Ground Measured Voltage Measured Reference ww w l VO o oO SIM970 Quad Digital Voltmeter ASRS 3 6 Remote Operation 3 3 Introduction Remote operation of the SIM970 is through a simple command lan guage documented in this chapter Both set and query forms of most commands are supported allowing the user complete control of the amplifier from a remote computer either through the SIM900 Main frame or directly via RS 232 see Section 1 6 2 1 See Table 1 1 for the specification of the DB 15 SIM Interface Con nector 3 3 1 Power on configuration 3 3 2 Buffers 3 3 3 Device Clear 3 4 Commands The initial settings for the remote interface are 9600 baud with no parity and no flow control and with local echo disabled CONS OFF Where appropriate the power on default value for parameters is listed in boldface in the command descriptions The SIM970 stores incoming bytes from the host interface in a 16 byte input buffer Characters accumulate in the input buffer until a command terminator either CR or LF is received at which point the message is parsed and executed
8. ASRS SIM970 Quad Digital Voltmeter 2 1 Operating Modes 2 7 of 8 0 readings This time constant equals 2 22 2 67 seconds for FPLC 60 Hz 50 Hz if the autocalibration regime is GND or GNDREF4 the time constant is 1 11 1 33 seconds if the autocalibration is NONE These time values are only valid for LOCAL triggering with its fixed sample rate Turning the filter ON reduces the reading to reading noise The filter also increases the instrument s settling time The filter is temporarily deactivated if there is a large change in the input voltage so as to improve the settling characteristic In order to change the digital filter setting from the remote interface issue the FLTR command SIM970 Quad Digital Voltmeter 4 SRS Description of Operation 2 2 Autoranging autoranging bits Weight B In addition to the operating mode the behavior of the instrument is determined by the autoranging settings the front panel lockout and the display blanking and display messaging options and the trigger mode With front panel operation autoranging can be on or off If the autoranging is ON the magnitude of the input voltage determines the current range for a given channel one of Ranges 1 through 4 in Table 2 1 The SIM970 under and over ranges according to the threshold specifications on Page vii Under the remote interface the instrument s user can achieve a finer degree of control over the autoranging behavior T
9. Measure VOLT n j 3 9 Measured Voltage VGND n 3 9 Measured Ground VREF n 3 9 Measured Reference TRIP n 3 9 Overvoltage Trip SOUT 3 9 Stop Streaming MESG n s 3 10 Display Message Configuration LOCL 3 10 Local Interface FPLC j Power Line Cycle Frequency DISX n z 3 10 Display Enable Disable FRNT n z 3 11 Front Panel Enable SCAL n j 3 11 Display Scale DVDR n z 3 11 Input Attenuator CHOP n z 3 11 Autocalibration FLTR n z 3 11 Digital Filter AUTO n 2 3 11 Autoranging State Trigger TMOD 2 3 12 Trigger Mode TCNT j 3 12 Trigger Count TREM j 3 12 Trigger Count Remaining TPER k 3 13 Trigger Period TRG 3 13 Trigger ASRS SIM970 Quad Digital Voltmeter 3 1 Index of Common Commands Status CLS 3 13 Clear Status STB i 3 13 Status Byte SRE 1 1 j 3 13 Service Request Enable ESR 1 3 13 Standard Event Status ESE i j 3 13 Standard Event Status Enable CESR i 3 14 Communication Error Status CESE i j 3 14 Communication Error Status Enable CHSR i 3 14 Channel Status CHSE i 3 14 Channel Status Enable PSTA z 3 14 Pulse STATUS Mode LBTN 3 14 Last Button Interface RST 3 15 Reset IDN 3 15 Identify TST 3 15 Self Test OPC 3 15 Operation Complete CONS z 3 16 Console Mode LEXE 3 16 Execution Error LCME 3 16 Command Error LDDE 3 17 Device Error TOKN z 3 17 T
10. Null parameter s 8 Parameter buffer overflow 10 Bad integer 11 Bad integer token 12 Bad token value 14 Unknown token ASRS SIM970 Quad Digital Voltmeter 3 4 Commands 3 17 LDDE Device Error Query the Last Device Dependent Error code Valid codes are Definition S a O No device error since last LDDE Cannot start Hardware fault Reading incomplete Converter overflow Converter underflow Reference bad Illegal mode ND OP 0NR Errors 4 and 5 may occur during a normal power on self test Error 7 is in response to a user s request for an illegal mode Section 2 3 3 TOKN z Token Mode Set query the token query mode to Z OFF 0 ON 1 If TOKN ON is set then queries to the SIM970 that return tokens will return a text keyword otherwise they return a decimal integer value Thus the only possible responses to the TOKN query are ON and 0 TERM z Response Termination Set query the term sequence to Z NONE 0 CR 1 LF 2 CRLF 3 or LFCR 4 The term sequence is appended to all query responses sent by the module and is constructed of ASCII character s 13 carriage return and 10 line feed The token mnemonic gives the sequence of characters 3 4 9 Serial communication commands Note that the SIM970 does not support serial flow control BAUD k Baud Rate Set query the baud rate to k At power on the baud rate defaults to 9600
11. Query responses from the SIM970 are buffered in a 64 byte output queue If the input buffer overflows then all data in both the input buffer and the output queue are discarded and an error is recorded in the CESR and ESR status registers The SIM970 host interface can be asynchronously reset to its power on configuration by sending an RS 232 style break signal From the SIM900 Mainframe this is accomplished with the SRST command if directly interfacing via RS 232 then use a serial break signal After receiving the Device Clear the interface is reset to 9600 baud and the CONS mode is turned OFF Note that this only resets the commu nication interface the basic function of the SIM970 is left unchanged to reset the voltmeter use RST The Device Clear signal will also terminate all streaming outputs from the SIM970 due to a VOLT query of multiple readings This section provides syntax and operational descriptions for remote commands ASRS SIM970 Quad Digital Voltmeter 3 4 Commands 3 4 1 Command syntax tokens The four letter mnemonic shown in CAPS in each command se quence specifies the command The rest of the sequence consists of parameters Commands may take either set or query form depending on whether the character follows the mnemonic Set only commands are listed without the query only commands show the after the mnemonic and optionally query commands are marked with a
12. Restoring the Default Configuration 1 6 1 6 SIM Interface nr amp Sue g ie see ee Eee 1 7 Description of Operation 2 1 2 1 Operating Modes s escaig pea o YR IAS 2 2 2 2 PULOLAA BING 5 8 8 ee gore Pie a Reh SPs 2 8 2 3 Controlling the Mode and Auto Settings 2 9 2 4 Other Instrument Features 2 10 25 APIS PORN oine Gv te coin a o Pk we ay a 2 10 Remote Operation 3 1 3 1 Index of Common Commands 3 2 3 2 Alphabetic List of Commands 3 4 33 Introduction nn on nn 3 6 34 Commands a 2 eine eee ee ee 3 6 3 5 Status Model a 23 4 3321 a bw ee 3 18 ii Contents ASRS SIM970 Quad Digital Voltmeter General Information The SIM970 Quad Digital Voltmeter part of Stanford Research Sys tems Small Instrumentation Modules family consists of four isolated digital voltmeter DVM channels Five and a half digits of resolution and overall accuracy are available for inputs within 20 volts Safety and Preparation for Use da WARNING The front panel inputs to the SIM970 are isolated from the Earth the power line outlet ground the metal chassis of the module and from each other No dangerous voltages are generated by the module However if a dangerous voltage is applied to an input it may be present on the outer casing of the input coaxial BNC connector and may cause injury or death Do not exceed 20 volts to the Earth at the positive center
13. also be cleared from the remote interface by issuing the command TRIP While a channel is tripped the SIM970 is safe and guaranteed to perform to specifications after the overload condition ceases The ASRS SIM970 Quad Digital Voltmeter 1 4 Power On 1 5 1 4 Power On magnitude of the input voltage must never exceed 60 V in order for the SIM970 to be safe and return to its specified performance The shield terminal of each front panel coaxial connector is not insulated and is potentially exposed to the user Applying dangerous voltages to this terminal is unsafe and may cause injury or death Although the inputs to the SIM970 are galvanically isolated from the Earth i e the chassis ground it is not recommended to exceed 20 V between the center input terminal and the Earth or between the shield terminal and the Earth The instrument is not guaranteed to perform to its specifications while these values are exceeded The SIM970 is guaranteed to perform to the specifications after the over load condition between an input terminal and the Earth ceases if none of the input terminals ever exceed 200 V relative to the Earth Upon power on the instrument performs a self test A message is displayed on the front panel during this time Gt dr 0 C n J uP All of the green annunciator LEDs subsequently turn on At the end of the test the LEDs turn off and the instrument starts taking voltage readings The
14. decimal point in the position expected after the scale change The first reading that appears on the display and at the remote interface after the dashes will have been taken under the new range settings The behavior of the SIM970 under remote triggering is identical to that under external triggering with only one difference Instead of an external TIL LOW edge at the TRIGGER input the source of a REMOTE trigger is the receipt of a TRG command at the remote interface External triggers received while under remote triggering will be ig nored and the other way around with the following exception If the SIM970 is idling after a complete reading sequence under EXTERNAL triggering and TMOD REMOTE is received it is necessary to give one more external trigger after that in order for the trig ger mode change to complete If an additional TTL trigger is not practical the transition EXTERNAL REMOTE can be made by first is suing TMOD LOCAL followed by TMOD REMOTE The same applies to switching the mode from REMOTE to EXTERNAL in the latter case issue one TRG after TMOD EXTERNAL SIM970 Quad Digital Voltmeter SRS Description of Operation ASRS SIM970 Quad Digital Voltmeter 3 Remote Operation In This Chapter This chapter describes operating the SIM970 over the serial interface 3 1 3 2 3 3 3 4 3 5 Index of Common Commands 3 2 Alphabetic List of Commands 3 4 Introduc
15. input signals in excess of 2 V will trip the protection circuitry The difference between DVDR OFF and OUT is the input resistance of the channel When OFF the channel still presents a 10 MQ load to the user when the attenuator is OUT the input impedance is gt 3 GQ CHOP n 1 z Autocalibration Set query the autocalibration regime for Channel n to Z NONE 0 GND 1 GNDREF4 2 or GNDREF3 3 See Section 2 1 3 for details FLTR n 2 Digital Filter Set query the digital filter state for Channel n to z OFF 0 ON 1 AUTO n z Autoranging State Set query the autoranging settings for Channel n The parameter Z is interpreted differently for integer or token values Valid tokens are OFF Turns all autoranging control bits auto bits off ALL Turns all auto bits on SCALE Enables automatic scale selection the scale is determined by the voltage reading SIM970 Quad Digital Voltmeter SRS Remote Operation DIVIDER Enables automatic input attenuator selection the attenuator is set based on the scale value CHOP Enables automatic selection of the autocalibration regime au tocalibration is set based on the scale value FILTER Enables automatic digital filter selection the filter is set based 3 4 6 Trigger commands on the scale value With the exception of OFF and ALL each token only turns on a single control bit while leaving the remaining bits u
16. 0 readings s GND 3 6 3 0 readings s GNDREF 3 2 4 2 0 readings s GNDREF4 3 6 3 0 readings s The display update frequency for Ranges 1 through 4 is the same 3 6 readings per second if FPLC is 60 Hz and 3 0 readings per second if FPLC is 50 Hz In order to change the autocalibration regime from the remote inter face use the CHOP command For maximum accuracy choose autocalibration regime GND if the in put attenuator is OFF or OUT and the regime GNDREF3 or GNDREF4 if the attenuator is ON Choosing autocalibration GND or NONE for attenu ator ON results in a somewhat decreased reading noise at the expense of an increased reading drift The digital filter produces a running exponential average of the re sults of input voltage readings The acceptable settings for the filter are ON and OFF For each legal combination of the scale the attenu ator and the autocalibration settings it is legal to have the filter ON and it is legal to have the filter OFF Range 4 has the filter ON whereas Ranges 1 through 3 turn the filter OFF The input to the filter is input voltage readings corrected for the offset error and the gain error Numerically the filter is a sim ple IIR infinite impulse response algorithm with a time constant 1 See Section 2 5 for the description of the instrument triggering options 2 This applies to LOCAL triggering only see Section 2 5 for the description of the instrument triggering options
17. Operation and Service Manual Quad Digital Voltmeter SIM970 SRS Stanford Research Systems Revision 1 19 e May 28 2010 Certification Stanford Research Systems certifies that this product met its published specifications at the time of shipment Warranty This Stanford Research Systems product is warranted against defects in materials and workman ship for a period of one 1 year from the date of shipment Service For warranty service or repair this product must be returned to a Stanford Research Systems authorized service facility Contact Stanford Research Systems or an authorized representative before returning this product for repair Information in this document is subject to change without notice Copyright Stanford Research Systems Inc 2003 2010 All rights reserved Stanford Research Systems Inc 1290 D Reamwood Avenue Sunnyvale CA 94089 USA Phone 408 744 9040 e Fax 408 744 9049 www thinkSRS com e e mail info thinkSRS com Printed in U S A Document number 9 01559 903 SRS SIM970 Quad Digital Voltmeter Contents General Information iii Safety and Preparation for Use iii MD Sr ee a E Ae eis Cie iv Notation 2 cido ts ole oh eh ee v Spe ificationsi 2 22 rs nee vi Getting Started 1 1 1 1 Introduction to the Instrument 1 2 1 2 Front Panel Operation 3 Ts hk ala 1 3 1 9 input Protection za nr RER oS 1 4 be Bower MN nee ae En Bar al 1 5 1 5
18. V 1000 mV 200 mV Attenuator OFF Autocalibration NONE Illegal Legal Legal Legal Autocalibration GND Illegal Range 2 Range 3 Range 4 Autocalibration GNDREF3 Ilegal Illegal Ilegal Ilegal Autocalibration GNDREF4 Illegal Illegal Illegal Illegal Attenuator ON Autocalibration NONE Legal Legal Legal Legal Autocalibration GND Legal Legal Legal Legal Autocalibration GNDREF3 Range 1 Legal Legal Legal Autocalibration GNDREF4 Legal Legal Legal Legal Attenuator OUT Autocalibration NONE Illegal Legal Legal Legal Autocalibration GND Illegal Legal Legal Legal Autocalibration GNDREF3 Ilegal Illegal Illegal Ilegal Autocalibration GNDREF4 Illegal Illegal Illegal Illegal 2 5 2 External triggering trigger latency For EXTERNAL and REMOTE triggering Table 2 3 Operating modes of the SIM970 for non local triggering reading of the local ground Voltage readings are made available to the display and the remote interface at the time an autocalibration sequence Table 2 2 is complete on a particular channel As a conse quence under certain conditions the displays can be seen updating the readings out of phase with one another If voltage readings for several channels are requested from the remote interface these can also arrive out of phase The instrument powers up into the locally triggered mode To switch to local triggering from one of the other modes issue TMOD LOCAL If the instrument is in the locally triggered mode an
19. annel is equal to 10 MQ For the attenuator OUT the resistance exceeds 3 GQ To change the input attenuator setting from the remote interface use the DVDR command SIM970 Quad Digital Voltmeter SRS 2 4 Description of Operation 5V Pa Ref A Center x1 A D r Converter 9M C u 10M Shield 1M Internal Ground Figure 2 1 Simplified schematic of the input stage circuit of the SIM970 Not all scale and autocalibration settings are compatible with input atten uator OFF or OUT See Section 2 3 3 Illegal Modes for more details The format of the data available through the remote interface is uniquely determined by the attenuator setting That is the settings for the scale and the autocalibration do not affect the position of the decimal point in the data that the SIM970 supplies through the remote interface Input attenuator setting Remote interface data format OFF Y XXXXXXX ON YX XXXXXX OUT Y XXXXXXX MN ny is either the minus character or is the space Y is the character 0 1 or 2 X is one of the characters 0 through 9 2 1 3 Autocalibration Autocalibration corrects the voltage reading for two kinds of errors offset error an offset error and a gain error The offset errorresults in a constant offset term added to the true value of the input voltage voltage read by the instrument
20. autocalibration regimes is as follows Autocalibration Sequence of readings NONE Input GND Input Ground GNDREF3 Input Reference Ground GNDREF4 Input Reference Input Ground Table 2 2 Autocalibration reading sequences for the SIM970 After each complete sequence of readings the front panel displays are updated with the new value of the input voltage corrected for the offset and if available gain errors and the new value of the input voltage becomes available to the remote interface An exception to this rule is the regime GNDREF4 in which the new corrected value is ASRS SIM970 Quad Digital Voltmeter Description of Operation 2 1 4 Digital filter shown on the displays and is available to the remote interface after a Reference reading is taken and after a Ground reading is taken For errors corrected once a reading of the internal ground and or reference is taken at the time the mode switches to the present mode This reading is used to correct all subsequent input voltage readings For LOCAL triggering the internal sampling frequency of the instru ment is fixed at 7 2 Hz if the power line frequency FPLC is 60 Hz and at 6 0 Hz if FPLC is 50 Hz Therefore the frequency at which cor rected voltage readings are displayed on the front panel and are avail able to the remote interface depends on the autocalibration regime as follows FPLC Hz Autocalibration 60 50 NONE 7 2 6
21. automatic trigger FPLC j Power Line Cycle Frequency Set query the power line rejection frequency to j 50 60 in Hz The FPLC value is retained in non volatile memory and is not mod ified by a power on reset DISX n z Display Enable Disable Set query the display for Channel n to z OFF 0 ON 1 When DISX n ON is set each new reading result is presented on the front panel display upon the completion of an autocalibration sequence DISX n OFF initially blanks the display but then allows MESG messages to be presented SRS SIM970 Quad Digital Voltmeter 3 4 Commands FRNT n z Front Panel Enable Set query the front panel lockout status for Channel n to z OFF 0 ON 1 When FRNT n OFF is sent the SIM970 stops responding to all front panel button presses for Channel n SCAL n j Display Scale Set query the front panel display scale for Channel n to j 20 2 1000 or 200 The setting j is one count greater than the maximum displayable value corresponding to 20 V 2 V 1000 mV or 200 mV DVDR n 2 Input Attenuator Set query the 1 10 input attenuator setting for Channel n to z OFF 0 ON 1 or OUT 2 When ON the 10 MQ 1 10 input attenuator is switched into the signal path permitting input signals up to 20 V to be measured without tripping the protection circuitry When OFF or OUT the input signal is not attenuated and
22. ce identification string The identification string is formatted as Stanford_Research_Systems SIM970 s n ver where SIM970 is the model number is a 6 digit serial number and is the firmware revision level TST Self Test There is no internal self test in the SIM970 after the power on so this query always returns 0 OPC Operation Complete Sets the OPC flag in the ESR register The query form OPC writes a 1 into the output queue when com plete but does not affect the ESR register SIM970 Quad Digital Voltmeter SRS Remote Operation Console Mode Set query the console mode to Z OFF 0 ON 1 CONS causes each character received at the input buffer to be copied to the output queue LEXE Execution Error Query the Last Execution Error code Valid codes are Value Definition 0 No execution error since last LEXE 1 Illegal value 2 Wrong token 3 Invalid bit 16 Nothing to do 17 Illegal message 18 Wrong mode Error 18 only occurs in response to trigger mode change requests that come while the instrument is BUSY and to TRG triggers received while not in the REMOTE trigger mode LCME Command Error Query the Last Command Error code Valid codes are Value Definition 0 No command error since last LCME 1 Illegal command 2 Undefined command 3 Ilegal query 4 Illegal set 5 Missing parameter s 6 Extra parameter s 7
23. connector signals are specified in Table 1 1 Direction Pin Signal Src gt Dest Description 1 SIGNALGND ME SIM Ground reference for signal 2 STATUS SIM gt MF Status service request GND asserted 5 V idle 3 RTS MF gt SIM HW Handshake unused in SIM970 4 CTS SIM gt MF HW Handshake unused in SIM970 5 REF_10MHZ MF gt SIM 10 MHz reference optional connection 6 5V MF gt SIM Power supply No connection in SIM970 7 15V MF SIM Power supply No connection in SIM970 8 PS_RTN MF gt SIM Power supply return 9 CHASSIS_GND Chassis ground 10 TXD MF SIM Async data start bit 0 5 V 1 GND 11 RXD SIM MF Async data start bit 0 5 V 1 GND 12 REF_10MHZ MF gt SIM 10 MHz reference optional connection 13 5V MF SIM Power supply 14 15V MF SIM Power supply No connection in SIM970 15 24V MF gt SIM Power supply No connection in SIM970 1 6 2 Direct interfacing Table 1 1 SIM interface connector pin assignments DB 15 The SIM970 is intended for operation in the SIM900 Mainframe but users may wish to directly interface the module to their own systems without the use of additional hardware The mating connector needed is astandard DB 15 receptacle such as Amp part number 747909 2 or equivalent A clean well regulated supply voltage of 5 0 V DC must be provided following the pinout specified in Table 1 1 G
24. d receives a TTL LOW at the TRIGGER input the SIM970 switches to its external trigger mode In this mode if the instrument is not busy taking reading sequences i e the BUSY output is LOW each LOW going edge at the TRIGGER input causes one or several sequences of readings to be taken on all channels Unlike the behavior in the LOCAL mode autocalibration sequences on the four channels are aligned That is a certain interval of time called trigger latency after the LOW going edge is received all four channels will start taking a reading of the input voltage at the same time After this reading is taken the channels will follow with taking the necessary autocalibration readings in each channel s sequence Clearly a situation is possible in which some channels have more SIM970 Quad Digital Voltmeter SRS Description of Operation trigger period readings to take than others Table 2 2 In this case channels that have less readings to take pad their sequences with readings of the input voltage which are ignored The result of a sequence of readings on a particular channel is available to the displays and the remote interface as soon as the sequence on that channel is complete The BUSY output stays HIGH from the time an external trigger is received until the last reading of the longest sequence is complete The following is an example of autocalibration sequences under EXTERNAL triggering with different settings for the fo
25. en segment digits will stop and the displays will turn dark Use the command DISX to turn displays on and off After the updates to the display have been turned off it is pos sible to paint alphanumeric messages on the display See the command MESG for more information If the updates have not been turned off by DISX n OFF n is channel number prior to issu ing MESG the message will only stay on the display for one display cycle a fraction of a second under local triggering but possibly many seconds for EXTERNAL or REMOTE triggering A trigger is an event that signals the SIM970 to take one or several volt age readings The SIM970 has three trigger modes LOCAL EXTERNAL and REMOTE To change the mode issue the TMOD command For all legal modes shown in Table 2 3 the digital filter may be either enabled or disabled For Ranges 1 through 4 digital filter settings are Range Digital filter 1 OFF 2 OFF 3 OFF 4 OFF In the locally triggered mode the instrument takes continuous read ings The BUSY output is always HIGH Although the four channels take readings synchronously there is no alignment between the sam ples of the input voltage That is each of the four channels can be in each of the legal autocalibration settings when e g Channel 1 is taking a reading of the input voltage Channel 2 can be taking a ASRS SIM970 Quad Digital Voltmeter 2 5 Triggering 2 11 Scale 20 V 2
26. ent with num ber arguments and with tokens See AUTO for more details Under front panel operation all of the auto bits are off or all of ASRS SIM970 Quad Digital Voltmeter 2 3 Controlling the Mode and Auto Settings 2 9 them are on To turn all the bits off from the remote interface is sue AUTO n 0 or AUTO n OFF where n is the channel number To turn all of them on issue AUTO n 15 or AUTO n ALL The front panel Auto LED annunciator for a given channel is active if AUTO is not 0 for the channel 2 3 Controlling the Mode and Auto Settings 2 3 1 Remote interface control The scale input attenuator autocalibration and digital filter settings for each channel can be controlled independently from the remote interface When issuing the respective commands the user should be aware of illegal modes Table 2 1 and Section 2 3 3 In order to get every channel of the instrument into one of Ranges 1 through 4 while under remote interface control issue the com mand LOCL The operating mode for each channel will change to the range appropriate for the channel s currently selected scale Ta ble 2 1 If one or several of the auto bits for a channel were on all of the auto bits for this channel will turn on otherwise AUTO for the channel will be OFF Alternatively a front panel button push will return the instrument into one of the Ranges See the next section 2 3 2 Front panel operation 2 3 3 Illegal mode
27. espect to the United States NIST is 6 x 10 of the reading SRS SIM970 Quad Digital Voltmeter General Information vii Measuring Characteristics Autoranging limits Input Trigger Measurement Output Operating Min Typ Max Units Range 1 1 90000 V Range 2 95000 1 99999 V Range 3 190 00 999 99 mV Range 4 199 999 mV Resistance 8 9 9 10 0 10 1 MO 3 GO Bias current 9 1 pA Terminals Isolated BNC 10 Protection center to shield 60 V Protection shield to Earth 200 V Source Local external or remote External input Rear BNG TTL active LOW Latency 480 us BUSY output Rear BNC TTL active HIGH BUSY impedance 50 Q Method 24 bit Delta Sigma A D converter A D linearity Corrected by firmware 11 Normal mode rejection 12 90 dB Common mode rejection DC 13 125 dB Update frequency 50 Hz FPLC 5 3 0 Hz Update frequency 60 Hz FPLC 5 3 6 Hz Settling time Ranges 1 3 5 14 1 s Settling time Range 4 5 14 10 s Displays Red numeric LED 0 30 Green LED range and autorange Temperature 15 0 40 C Power 5 VDC Supply current 480 mA Conditions 8 Input resistance is 10 MQ for Ranges 1 through 4 Operating modes with gt 3 GQ input resistance exist Table 2 1 0 Amphenol 31 10 4052 or similar 9 At 23 C 1 Included in the accuracy spec
28. f the SIM970 See Section 3 5 for the status model CLS Clear Status CLS immediately clears the ESR CESR and the SIM970 status reg isters STB 1 Status Byte Query the Status Byte Register bit i Execution of the STB query without the optional bit i always causes the STATUS signal to be deasserted Note that STB will not clear STATUS even if bit is the only bit presently causing the STATUS signal STB clears the TRIG bit Section 3 5 1 in the SB register SRE i j Service Request Enable Set query the Service Request Enable Register bit i to j ESR i Standard Event Status Query the Standard Event Status Register bit i Upon execution of ESR the returned bit s of the ESR register are cleared ESE i ti Standard Event Status Enable Set query the Standard Event Status Enable Register bit i to j SIM970 Quad Digital Voltmeter SRS Remote Operation CESR i Communication Error Status Query the Communication Error Status Register bit Upon executing a CESR query the returned bit s of the CESR reg ister are cleared CESE 61 j Communication Error Status Enable Set query the Communication Error Status Enable Register bit to j CHSR i Channel Status Query the Channel Status Register bit Upon executing a CHSR query the returned bit s of the CHSR reg ister are cleared CHSE i
29. gal Legal Legal Autocalibration GNDREF3 Ilegal Illegal Ilegal Ilegal Autocalibration GNDREF4 Illegal Illegal Illegal Illegal For LOCAL triggering 2 1 1 Scale Table 2 1 Operating modes of the SIM970 For all legal modes shown the digital filter may be either enabled or disabled For Ranges 1 through 4 digital filter settings are Range Digital filter 1 OFF 2 OFF 3 OFF 4 ON Ranges 1 through 4 are the only operating modes accessible through the front panel A much richer variety of modes are available through the remote interface The next Section Remote Operation dis cusses the commands necessary to put some or all of the channels of a SIM970 into a given mode These commands are also briefly dis cussed in Sections 2 1 1 through 2 1 4 and Section 2 2 which describe the aspects of operation these settings affect The scale setting for a given channel is the position of the decimal point on the front panel display for this channel ASRS SIM970 Quad Digital Voltmeter 2 1 Operating Modes 2 1 2 Input attenuator Scale setting Front panel display format 20 V 19 9999 V 2V 1 99999 V 1000 mV 999 99 mV 200 mV 199 999 mV The scale setting for a channel is related to the range the channel may be on but the two terms are not equivalent A range is an operating mode and consists of other settings in addition to the scale setting For Ranges 1 through 4 accessible from the front panel the
30. here are four auto bits set by the command AUTO Token Meaning 1 2 4 8 it 0 SCALE Input voltage determines the scale 1 DIVIDER Current scale determines the input attenuator setting 2 CHOP Current scale determines the autocalibration regime 3 FILTER Current scale determines the digital filter setting One or several bits can be set by AUTO For example the behavior of the instrument after issuing AUTO 1 5 will be as follows For Channel 1 the input voltage will set the scale which in turn will set the autocalibration regime to the one that corresponds to the range for the current scale in Table 2 1 However the complete operating mode will not be set to this range In this example the position of the decimal point on the display of Channel 1 and the channel s autocalibration regime will change with the magnitude of the input voltage but neither the input attenuator nor the digital filter settings will If further in this example the input attenuator for Channel 1 has been set to ON and the digital filter set to OFF the channel s operating mode will respond in the following way to an increase in the input voltage Input voltage Scale Attenuator Autocalibration Filter OmV to 199 999 mV 200mV ON GND OFF 200 00 mV to 999 99mV 1000mV ON GND OFF 1 00000 V to 1 99999 V 2V ON GND OFF 2 0000 V to 19 9999 V 20V ON GNDREF4 OFF Unlike with other commands the behavior of AUTO is differ
31. ifications 3 For 1kQ unbalance in the shield 4 To within 3 counts of the final reading on a fixed range for an input voltage step of 50 of the maximum voltage for the range for 0Q source impedance 15 Non condensing 1 1 12 At power line frequency FPLC 59 Hz to 61 Hz or 49 Hz to 51 Hz 1 1 SIM970 Quad Digital Voltmeter ASRS viii General Information General Characteristics Number of channels Interface Connectors Weight Dimensions 4 Serial RS 232 through SIM interface BNC 4 front 10 2 rear DB 15 male SIM interface 2 3 lbs 3 0 W x 3 6 H x 7 0 D ASRS SIM970 Quad Digital Voltmeter 1 Getting Started In This Chapter This chapter gives you the necessary information to get started quickly with your SIM970 Quad Digital Voltmeter 1 1 1 2 1 3 1 4 1 5 1 6 Introduction to the Instrument 1 2 Il BEODEPAnEL rot rad anne 1 2 1 1 2 Respalda a Bes he wh 1 3 Front Panel Operation 1 3 Input Protector a A Ss 1 4 POwEer ON e ecen tata a re ee 1 5 Restoring the Default Configuration 1 6 SIM Interface ois ss senetan o eee eee 1 7 1 6 1 SIM interface connector 1 7 1 6 2 Direct interfacing is el re 1 7 1 2 Getting Started 1 1 Introduction to the Instrument chassis ground remote interface 1 1 1 Front panel The SIM970 Quad Digital Voltmeter is designed to make precision low f
32. instrument does not save operation related settings The only non volatile settings that are retained while the instrument is not powered are calibration values and the power line frequency 60 Hz or 50Hz The latter equals the principal rejection frequency of an internal filter The power on configuration of the remote interface is detailed in Section 3 3 1 SIM970 Quad Digital Voltmeter SRS 1 6 Getting Started 1 5 Restoring the Default Configuration The default configuration of the SIM970 is Range 1 on all four chan nels with autoranging on more precisely autoranging set to ALL see Section 2 2 with LOCAL triggering It is the power on configuration To restore it turn the SIM900 Mainframe power off and then on The same configuration can also be reached from the remote interface by issuing the RST command SRS SIM970 Quad Digital Voltmeter 1 6 SIM Interface 1 6 SIM Interface The primary connection to the SIM970 Quad Digital Voltmeter is the rear panel DB 15 SIM interface connector Typically the SIM970 is mated to a SIM900 Mainframe via this connection either through one of the internal mainframe slots or the remote cable interface It is also possible to operate the SIM970 directly without using the SIM900 Mainframe This section provides details on the interface 1 6 1 SIM interface connector The DB 15 SIM interface connector carries all the power and commu nication lines to the instrument The
33. nchanged When an integer is given for Z it is interpreted as a binary encoded bitfield Weight Bit Flag 1 0 SCALE 2 1 DIVIDER 4 2 CHOP 8 3 FILTER Queries always return the integer representation of the bitfield re gardless of the setting of the TOKN command The trigger commands always operate on all channels TMOD z Trigger Mode Set query the trigger mode to z LOCAL 0 EXTERNAL 1 or REMOTE 2 TCNT j Trigger Count Set query the number of samples per trigger to j The maximum j 65535 TREM j Trigger Count Remaining Set query the number of samples remaining to j TREM is used to shorten or terminate an active triggered ensemble of readings j 0 will terminate the ensemble Note that TREM can only decrease the remaining trigger count if j exceeds the remaining count it is ignored ASRS SIM970 Quad Digital Voltmeter 3 4 Commands TPER k Trigger Period Set query the period between samples to k in ms TPER controls the period between multiple TCNT samples following an EXTERNAL or REMOTE trigger event k must be an integer multiple of 10 ms and not exceed 655350 ms about 11 minutes TRG 3 4 7 Status commands Trigger Initiate a remote trigger The SIM970 must first be set to TMOD REMOTE before issuing a TRG command The Status commands query and configure registers associated with status reporting o
34. o Power Supply 13 gt 5V DC 8 9 gt Ground Supply return current Table 1 2 SIM970 direct interface cable pin assignments The initial serial port settings at power on are baud rate 9600 8 bits no parity 1 stop bit and no flow control These may be changed with the BAUD or PARI commands The maximum standard baud rate that the SIM970 supports is 38400 The minimum baud rate is 110 Above 38400 the SIM970 can be set to the following non RS 232 standard baud rates 62500 78125 104167 156250 Note that these rates are typically not accessible on 1 Although the serial interface lines on the DB 15 do not satisfy the minimum voltage levels of the RS 232 standard these lines are typically compatible with desktop personal computers ASRS SIM970 Quad Digital Voltmeter 1 6 SIM Interface 1 9 a standard PC RS 232 port but can be used between the SIM970 and the SIM900 Mainframe SIM970 Quad Digital Voltmeter 4 SRS Getting Started ASRS SIM970 Quad Digital Voltmeter 2 Description of Operation In This Chapter To use the whole spectrum of SIM970 s capabilities one needs to understand the instrument s operating modes Ranges 1 2 3 and 4 accessible from the front panel are only four of the operating modes available to the instrument s user 2 1 2 2 2 3 2 4 2 5 Operating Modes o o 2 2 2 1 Seal rra Ban en Be 2 2 2 1 2 Input attenuator ea S
35. oken Mode TERM z 3 17 Response Termination Serial Communications BAUD k PARI z 3 17 3 17 Baud Rate Parity SIM970 Quad Digital Voltmeter ASRS 3 4 Remote Operation 3 2 Alphabetic List of Commands CLS ESE 5 U ESR i IDN OPC RST SRE 6 j STB 1 TRG TST 3 13 Clear Status 3 13 Standard Event Status Enable 3 13 Standard Event Status 3 15 Identify 3 15 Operation Complete 3 15 Reset 3 13 Service Request Enable 3 13 Status Byte 3 13 Trigger 3 15 Self Test A AUTO n 2 3 11 Autoranging State B BAUD k 3 17 Baud Rate C CESE i j CESR i CHOP n z CHSE i U CHSR 1 CONS z 3 14 Communication Error Status Enable 3 14 Communication Error Status 3 11 Autocalibration 3 14 Channel Status Enable 3 14 Channel Status 3 16 Console Mode D DISX n z DVDR n z 3 10 Display Enable Disable 3 11 Input Attenuator F FLTR n z FPLC j FRNT n z 3 11 Digital Filter 3 10 Power Line Cycle Frequency 3 11 Front Panel Enable H HELP 3 9 Instrument Help L LBTN LCME 3 14 Last Button 3 16 Command Error ASRS SIM970 Quad Digital Voltmeter 3 2 Alphabetic List of Commands LDDE LEXE LOCL 3 17 Device Error 3 16 Execution Error 3 10 Local Interface M MESG n s 3 10 Display Message P PARI
36. or Undefined for the SIM970 Device Clear Indicates that the SIM970 received the Device Clear signal an RS 232 break Clears the input buffer and the output queue and resets the command parser 3 5 6 Communication Error Status Enable CESE The CESE acts as a bitwise AND with the CESR register to produce the single bit CESB message in the Status Byte Register SB The register can be set and queried with the CESE command At power on this register is cleared 3 5 7 Channel Status CHSR The Channel Status Register consists of 8 event flags each of the flags is set by the corresponding event and cleared only by reading the register or with the CLS command Reading a single bit with the CHSR i query clears only bit i SIM970 Quad Digital Voltmeter ASRS Remote Operation 3 22 Weisht Bit Flag 1 0 Tripl 2 1 Trip2 4 2 Trip3 8 3 Trip4 16 4 Seql 32 5 Seq2 64 6 Seg3 128 7 Seq4 Tripn Input Overload Indicates that Channel n had an input over voltage protection trip Seqn Reading Sequence Complete Indicates that a triggered ensem ble of reading sequences for Channel n has completed This bit is set for all trigger modes including LOCAL in the latter case the ensemble consists of a single autocalibration sequence While reading this register with the CHSR query will clear all Tripn bit s that are set it will not reset the overvoltage protection circ
37. par as 2 3 2 1 3 Autocalibration 2 4 214 Digital filtet rn he Reo Cr RE Ha 2 6 AUTOLANEINE s aa aa ste 2 8 Controlling the Mode and Auto Settings 2 9 2 3 1 Remote interface control 2 9 2 3 2 Front paneloperation 2 9 2 3 3 Wegal modes oi cack on oe 8 3 00 2 9 Other Instrument Features 2 10 2 4 1 Front panellockout 2 10 2 4 2 Display blanking and messages 2 10 Triggering o ra 22 Se AAA Dan 2 10 25 1 Local TIS CTI nn ae 2 10 2 5 2 External triggering ban ar ah or was 2 11 2 5 3 Remote triggering ros ee Ak we ae 2 13 2 2 Description of Operation 2 1 Operating Modes An operating mode of the SIM970 is a combination of settings for the scale the input attenuator the autocalibration and the digital filter Table 2 1 summarizes the available modes Scale 20 V 2V 1000 mV 200 mV Attenuator OFF Autocalibration NONE Illegal Legal Legal Legal Autocalibration GND Illegal Range 2 Range 3 Range 4 Autocalibration GNDREF3 Ilegal Illegal Ilegal Illegal Autocalibration GNDREF4 Illegal Illegal Illegal Illegal Attenuator ON Autocalibration NONE Legal Legal Legal Legal Autocalibration GND Legal Legal Legal Legal Autocalibration GNDREF3 Legal Legal Legal Legal Autocalibration GNDREF4 Range 1 Legal Legal Legal Attenuator OUT Autocalibration NONE Illegal Legal Legal Legal Autocalibration GND Illegal Le
38. re is a one to one correspondence between the range and the scale However with the help of the remote interface the scale for a given mode can be set to every scale in Table 2 1 that is allowed In other words the position of the decimal point on the front panel display does not uniquely determine the input attenuator the autocalibration and the digital filter settings if the remote interface is utilized To change the scale from the remote interface issue the SCAL com mand If the reading overloads the maximum value that is possible to dis play on a given scale the front panel display format can change to accommodate the higher reading If such accommodation is not possible the following is displayed I ap 1 Ol Ol The internal analog to digital converter of the SIM970 can only sam ple a voltage between 2 5 and 2 5 volts In order to measure higher voltages the input signal must be attenuated inside the SIM970 The input attenuator is a 1 10 voltage divider that can be inserted into the signal path The input attenuator can be ON in which case the voltage sampled by the converter is 1 10th of the input voltage it can be OFF in which case the input voltage is sampled directly and it can be OUT in which case the voltage is also sampled directly and the resistors that comprise the attenuator are disconnected from the input signal For the attenuator OFF and for the attenuator ON the input resistance of a ch
39. requency voltage measurements with excellent long term accu racy The four channels are galvanically isolated from one another and from the Earth chassis ground Autocalibration is performed with every reading by sequentially measuring not only the input voltage but also the ground voltage and a fixed mid scale voltage against a calibrated internal reference This autocalibration routine virtually eliminates offsets and scale errors Computer access through the SIM900 Mainframe RS 232 or GPIB permits input voltage logging with 24 bits of resolution This re mote interface allows the user to exercise detailed control over the instrument s settings An external trigger input allows synchronization of voltage readings on all four channels for applications requiring coincidental readings The same functionality can also be achieved through the remote interface RS SIM970 Quad DVM Figure 1 1 The SIM970 front panel ASRS SIM970 Quad Digital Voltmeter 1 2 Front Panel Operation 1 3 Figure 1 2 The SIM970 rear panel 1 1 2 Rear panel For a description of the rear panel connectors and triggered opera tion see Section 2 5 1 2 Front Panel Operation BNC Each channel of the SIM970 measures a voltage applied between the center terminal center inner terminal of a front panel coaxial BNC connector and shield terminal the shield outer terminal of the connector The center terminal is the positive input wherea
40. round must be provided on Pin 8 with chassis ground on Pin 9 The STATUS signal may be monitored on Pin 2 for a low going TTL compatible output indicating a status message See Section 3 5 for the description of status messages SIM970 Quad Digital Voltmeter SRS 1 8 Getting Started A CAUTION The SIM970 has no internal protection against reverse polarity or overvolt age on the 5 V power supply pin A supply voltage above 5 5 V is likely to damage the instrument 1 6 2 1 Direct interface cabling 1 6 2 2 Serial settings If the user intends to directly wire the SIM970 independent of the SIM900 Mainframe communication is usually possible by directly connecting the appropriate interface lines from the SIM970 DB 15 plug to the RS 232 serial port of a personal computer Connect RXD from the SIM970 directly to RD on the PC TXD directly to TD and similarly RTS gt RTS and CIS gt CTS In other words a null modem style cable is not needed To interface directly to the DB 9 male DTE RS 232 port typically found on contemporary personal computers a cable must be made with a female DB 15 socket to mate with the SIM970 and a female DB 9 socket to mate with the PC s serial port Separate leads from the DB 15 need to go to the power supply making what is sometimes know asa hydra cable The pin connections are given in Table 1 2 DB 15 F to SIM970 Name DB 9 F 10 3 TxD 11 2 RxD 5 Computer Ground t
41. s If the front panel button for a channel is pushed while the SIM970 is under remote control the instrument will return each channel into one of the Ranges of Table 2 1 Table 2 3 for non local triggering This is done by turning all of the AUTO bits for the channel ON if one or several of them were on and leaving them OFF if they were 0 Autoranging will subsequently select the appropriate range Having control over separate components of the operating mode makes it possible to request an illegal mode Table 2 1 Table 2 3 for non local triggering Illegal modes are accepted via forcing the input attenuator setting to ON and leaving the rest of the pro posed settings intact A Device Dependent Error will be issued with a DDE_ ILLEGAL MODE return code see the command LDDE for more details SIM970 Quad Digital Voltmeter SRS 2 10 Description of Operation 2 4 Other Instrument Features 2 4 1 Front panel lockout The command FRNT makes it possible to enable or disable the re sponse of the instrument to front panel events With FRNT OFF for a particular channel front panel button pushes for that channel have no effect FRNT ON must be issued to regain front panel control 2 4 2 Display blanking and messages 2 5 Triggering trigger 2 5 1 Local triggering It is possible to disable the front panel display for one or all chan nels Updates to the channel s display and all multiplexed electrical activity at the sev
42. s the shield is the negative input You can only reach specific modes of operation which are Ranges 1 through 4 Table 2 1 from the front panel When the instrument powers up autoranging Section 2 2 is turned on When autorang ing is on the current range is determined by the magnitude of the input voltage The automatically selected range will generally be the one that will accommodate the input voltage without overloading the input stage of the instrument and will produce a display read ing with the highest possible resolution When autoranging is on short front panel button presses do nothing except as noted below for operation from the remote interface In order to turn autoranging off hold the front panel button for a SIM970 Quad Digital Voltmeter SRS Getting Started 1 3 Input Protection specific channel for more than 1 5 seconds The Auto annunciator will turn off After autoranging is OFF short button presses will switch between ranges in the sequence Range 1 Range 2 Range 3 Range 4 and back to Range 1 starting from the current range To turn autoranging back on hold the button for more than 1 5 sec onds Auto will turn on The remote interface allows the user to exercise specific control over the operation of the SIM970 If from the remote interface the instru ment had been put into an operating mode that is not one of Ranges 1 through 4 see Section 2 1 for a description of operating modes a fron
43. se AND with the ESR register to produce the single bit ESB message in the Status Byte Register SB The register can be set and queried with the ESE command At power on this register is cleared 3 5 5 Communication Error Status CESR The Communication Error Status Register consists of 8 event flags each of the flags is set by the corresponding event and cleared only by reading the register or with the CLS command Reading a single bit with the CESR i query clears only bit i ASRS SIM970 Quad Digital Voltmeter 3 5 Status Model 3 21 Weisht Bit Flag 1 0 PARITY 2 1 FRAME 4 2 NOISE 8 3 HWOVRN 16 4 OVR 32 5 RTSH 64 6 CTSH 128 7 DCAS PARITY FRAME NOISE HWOVRN OVR RTSH CTSH DCAS Parity Error Set by serial parity mismatch on the incoming data byte Framing Error Set when an incoming serial data byte is missing the STOP bit Noise Error Set when an incoming serial data byte does not present a steady logic level during each asynchronous bit period window Hardware Overrun Set when an incoming serial data byte is lost due to internal processor latency Causes the input buffer to be flushed and resets the command parser Input Buffer Overrun Set when the input buffer is overrun by the incoming data Causes the input buffer to be flushed and resets the command parser Undefined for the SIM970 A command error Indicates a parser detected err
44. t 6 of the SRE is undefined setting it has no effect and reading it always returns 0 This register is set and queried with the SRE command At power on this register is cleared SIM970 Quad Digital Voltmeter ASRS 3 20 Remote Operation 3 5 3 Standard Event Status ESR The Standard Event Status Register consists of 8 event flags These event flags are all sticky bits that are set by the corresponding events and cleared only by reading or with the CLS command Reading a single bit with the ESR i query clears only bit i Weight Bit Flag 1 0 OPC 2 1 INP 4 2 OYE 8 3 DDE 16 4 EXE 32 5 CME 64 6 URO 128 7 PON OPC Operation Complete Set by the OPC command INP Input Buffer Error Indicates data has been discarded from the input buffer OYE Query Error Indicates data in the output queue has been lost DDE Device Dependent Error Indicates that the SIM970 had a de layed execution error due to a request for an illegal mode a power on self test failure or a converter fault EXE Execution Error Indicates the error in a command that was successfully parsed Out of range parameters are an example CME Command Error Indicates a command parser detected error URQ User Request Indicates that a front panel button was pressed PON Power On Indicates that an off to on transition has occurred 3 5 4 Standard Event Status Enable ESE The ESE acts as a bitwi
45. t panel button press will take the SIM970 into one of Ranges 1 through 4 Range closest to the remotely selected operating mode will be chosen See Section 2 3 2 for more details The preceding description of front panel buttons behavior also ap plies to EXTERNAL triggering in addition to LOCAL triggering See Section 2 5 2 for a discussion of externally triggered behavior Each input to the SIM970 i e the voltage difference between the center terminal of each front coaxial connector and the connector s shield terminal should not exceed 20V at all times While this voltage is exceeded the instrument is not guaranteed to perform to its specifications If the absolute magnitude of the input voltage exceeds 30 V with the input attenuator ON Section 2 1 2 or 3 0 V for input attenuator OFF or OUT an input protection circuit will be activated tripped disconnecting the input voltage from the rest of the SIM970 s circuitry If this happens the following message is displayed on the front panel Bie ue If the protection circuit is activated there will be no new voltage readings available through the remote interface In order to clear the protection circuit push the front panel button for the tripped channel once If the overload condition no longer exists the protection circuit will turn off The instrument will automatically attempt to clear the trip after the overload condition has occurred but will do so only once The trip can
46. terminal of each input connector Do not exceed 20 volts to the Earth at the negative shield terminal of each input connector Do not install substitute parts or perform unauthorized modifications to this instrument The SIM970 is a double wide module designed to be used inside the SIM900 Mainframe Do not turn on the power to the mainframe or apply voltage inputs to the module until the module is completely inserted into the mainframe and locked in place 111 iv General Information Symbols you may Find on SRS Products Alternating current Caution risk of electric shock Frame or chassis terminal Caution refer to accompanying documents Earth ground terminal SRS SIM970 Quad Digital Voltmeter General Information v Notation The following notation will be used throughout this manual A WARNING A warning means that injury or death is possible if the instructions are not obeyed A CAUTION A caution means that damage to the instrument or other equipment is possible e Front panel buttons are set as Button Adjust AY is shorthand for Adjust 4 amp Adjust 1 e Front panel indicators are set as Overload Signal names are set as BUSY Signal levels are set as HIGH e Remote command names are set as IDN Literal text other than command names is set as OFF Special ASCII characters are set as CR SIM970 Quad Digital Voltmeter 4 SRS vi General Information Specifica
47. tion ip 2a mas Ea 3 6 3 3 1 Power on configuration 3 6 332 Buffers anaue ee black ene Ble ED Ape es 3 6 3 3 3 DeviceClear 222222222 3 6 Commands ii ra wre rn ee 3 6 3 4 1 Command syntax ser ra 3 7 3 4 2 Notation 0 00000 02 eae 3 8 3 4 3 Generalcommands 3 9 3 4 4 Measure commands 3 9 3 45 Configuration commands 3 10 3 4 6 Trigger commands 3 12 3 4 7 Statuscommands 3 13 3 4 8 Interface commands 3 14 3 4 9 Serial communication commands 3 17 Status Model 2 0 0 0 0 sv 08 ewe 3 18 3 5 1 7 Status Dye e 3 19 3 5 2 Service Request Enable SRE 3 19 3 5 3 Standard Event Status ESR 3 20 3 5 4 Standard Event Status Enable ESE 3 20 3 5 5 Communication Error Status CESR 3 20 3 5 6 Communication Error Status Enable CESE 3 21 3 5 7 Channel Status CHSR eye 3 21 3 5 8 Channel Status Enable CHSE 3 22 3 2 Remote Operation 3 1 Index of Common Commands Symbol Definition i Bit number 0 7 j k Unsigned integer n Channel number 1 4 n 0 means all S Character string zZ Literal token Required for queries illegal for set commands var Parameter always required var Required parameter for set commands illegal for queries var Optional parameter for both set and query forms General HELP 3 9 Instrument Help
48. tions Ranges Resolution and Noise Under front panel operation the SIM970 has four voltage ranges See Table 2 1 for more details Maximum input Noise R y ange voltage Resolution t counts rms 2 3 1 19 9999 V 100 uV 1 5 2 1 99999 V 10 uV 0 8 3 999 99 mV 10 uV 0 8 4 199 999 mV 1uV 1 0 Conditions 1 71 2 digits or 24 bits of resolution are available through the remote interface 2 One count is a unit change in the least significant digit Each front panel display of the SIM970 has a capacity of 199999 counts 3 Measured over 360 consecutive readings Accuracy Accuracy specifications 4 5 are the same for all four channels The four channels have isolated circuitry so no channel matching speci fications exist In reading x 1079 counts 2 Range 24 hours 90 days 1 year 5 23 1 C 23 5 C 23 5 C 1 10 2 50 2 80 2 2 2 2 50 2 80 2 3 2 2 50 2 80 2 4 2 4 50 6 80 6 Relative to calibration standards 7 Transfer accuracy 24 hour count error 2 typ 6 Conditions 4 Inside a fully occupied SIM900 Mainframe following a 2 hour warmup 5 Specifications apply to Ranges 1 through 4 only locally triggered Ta ble 2 1 6 Within 10 minutes and 0 5 C within 10 of the initial value on a fixed range input voltage between 10 and 100 of the maximum for the range 7 The absolute accuracy of the SRS factory calibration standard with r
49. uit To do that the user must issue the TRIP command As long as Channel n remains tripped off the Tripn bit will be continuously reasserted 3 5 8 Channel Status Enable CHSE The CHSE acts as a bitwise AND with the CHSR register to produce the single bit CHSB message in the Status Byte Register SB The register can be set and queried with the CHSE command At power on this register is cleared ASRS SIM970 Quad Digital Voltmeter
50. ur channels Channel 1 2 3 4 Autocalibration NONE GND GNDREF3 GNDREF4 Sequence Input Input Input Input Input Ground Reference Reference Input Input Ground Input Input Input Input Ground where bold face indicates the reading after which the front panel displays and the remote interface are updated It is possible to take more than one sequence of readings for each external trigger The number of sequences to take is set by the remote command TCNT this number is 1 upon power on The beginnings of the sequences will be separated by the trigger period set by the command TPER If the period is too short for the longest reading sequence among all channels to complete a device error will be generated and the period will be reset to its default value 1000 ms The period is equal to this default value upon power on If TCNT is greater than one the BUSY output will stay HIGH for the whole duration of the ensemble of reading sequences caused by a single external trigger event including the waiting idle time between the sequences The instrument buffers one external trigger event If an external trigger arrives when the SIM970 is busy that is the BUSY output is HIGH this trigger will be serviced after the triggered readings are complete All additional triggers received afterwards and while the instrument is still BUSY will be ignored If a trigger is buffered the BUSY output will become LOW when it normally
51. us Byte SB The Status Byte is the top level summary of the SIM970 status model When masked by the Service Request Enable Register a bit set in the Status Byte causes the STATUS signal to be asserted on the rear panel SIM interface connector Weight Bit Flag 1 0 CHSB 2 1 TRIG 4 2 undef 0 8 3 undef 0 16 4 IDLE 32 5 ESB 64 6 MSS 128 7 CESB CHSB TRIG IDLE EsB MSS CESB Channel Status Summary Bit Indicates whether one or more of the enabled flags in the Channel Status Register has become true Trigger Status Bit Indicates that a trigger event either TRG or an external TTL LOW at the TRIGGER input has been received Note that this is the only bit in the Status Byte that is cleared by STB Indicates that the input buffer is empty and the command parser is idle Can be used to help synchronize SIM970 query responses Event Status Bit Indicates whether one or more of the enabled events in the Standard Event Status Register is true Master Summary Status Indicates whether one or more of the enabled status messages in the Status Byte Register is true Communication Error Summary Bit Indicates whether one or more of the enabled flags in the Communication Error Status Register has become true 3 5 2 Service Request Enable SRE Each bit in the SRE corresponds one to one with a bit in the SB regis ter and acts as a bitwise AND of the SB flags to generate MSS Bi
52. would and will stay LOW for a minimum of 10ms At the end of this period the output will go HIGH and the next triggered reading sequence will start Triggered reading sequences cannot be interrupted They always complete When the first EXTERNAL trigger is received while the instrument is in the local trigger mode the current locally triggered sequences will complete This first trigger will be serviced as a buffered trigger ASRS SIM970 Quad Digital Voltmeter 2 5 Triggering 2 13 2 5 3 Remote triggering In order to switch to or from EXTERNAL triggering issue the TMOD command If the remote interface is not available the only way from EXTERNAL to LOCAL triggering is through a power cycle The external TRIGGER input is active LOW and hence triggers can be caused by simply shorting the center terminal of this BNC con nector to its shield However the trigger signal must be debounced Shorting the two terminals of the TRIGGER input without debouncing will most likely cause multiple signal edges and hence multiple triggers of which the first two will be recognized the second one will be buffered The effect of the front panel buttons in the externally triggered mode is the same as it is under local triggering Table 2 3 details the avail able ranges However several readings typically need to be taken until the operating mode change is complete During this change dashes will be displayed on the front panel with the

Quad Digital Voltmeter - Stanford Research Systems

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