PICO ADC-16 - Electrocomponents
Contents
1. or adc 1l6ms lib Microsoft Visual C 32 bit applications The following files must be in the same directory adc16tes rch adcl6w h either adc1616 dll All 16 bit applications or adc1632 dll All 32 bit applicaitons C C programs can access all versions of the driver If adc16 h is included in a C program the PREF1 macro expands to extern C this disables name mangling or decoration as Microsoft call it and enables C routines to make calls to the driver routines using C headers Pascal The program adcl6b pas can be compiled either as a stand alone program SDEFINE MAIN or as a unit which can be linked into other programs SUNDEF MAIN adcl6b pas includes the driver using the SL adcl6 drv obj and L commdrv obj commands it also provides pascal prototypes for each of the routine in the driver This program has been tested with Borland Turbo Pascal V6 0 Basic The DOS driver does not work with DOS Basic however the example program adc16 bas shows how to drive the ADC 16 directly Excel The easiest way to get data into Excel is to use PicoLog for Windows If however you need to do something that is not possible using PicoLog you can use an Excel macro to read in a set of data values The Excel Macro language is similar to Visual Basic Excel 5 The example ADC1616 XLS reads in 20 values from channels 1 and 2 one per second and assigns them to cells A1 B20 Excel 7 Th2. 7 is the msb and bit 0 is the Isb 7 5 Set the channel 000 channel 1 001 channel 2 110 channel 7 111 channel 8 1 4 0111 8 bit 1000 9 bit 1110 15 bit 1111 16 bit Mode 1 single ended 0 differential If the mode bit is 1 each channel voltage will be measured with respect to ground single ended operation If the mode bit is 0 then adjacent channels act as differential pairs Differential operation can be useful if problems due to earth loops are encountered If you select channel 1 and differential operation the ADC 16 will measure the voltage between channels 1 and 2 Similarly selecting channel 3 will cause the voltage to be measured between channels 3 and 4 Whilst in differential mode selecting even channel numbers may give incorrect results The control byte 00000001 is a request for the version number see below for details of the version response The following examples show complete control bytes and their effects 000 1111 1 channel 1 16 bits single ended 11001110 channels 7 and 8 8 bits differential mode Response format On receipt of a control byte containing a valid data request the ADC 16 will start a conversion cycle At the end of this conversion the ADC 16 will respond by sending three bytes Note that three bytes are sent even for 8 bit readings 1 Sign value gt 0 ASCII hex 2B value lt ASCII hex 2D For example the value 41349 which is hex 85A1 would
3. the measured and filtered values The filter_factor sets the proportion that is added The filter_factor must be between 1 and 100 A filter_factor of 1 means add all of the difference effectively no filtering and 100 means add 1 100 of the difference very slow filtering A factor of 10 gives a time constant of about a minute when all channels are selected The effective resolution is increased by the filter_factor and the noise floor is reduced by approximately the square root of the filter factor adcl6_get_value short int adcl6_get_value long far value unsigned short int port short int channel Once you open the driver it constantly takes readings from the ADC 16 When you call this routine it immediately sets value to the most recent ADC reading for the specified channel If a reading is available it returns TRUE otherwise it returns FALSE It will normally return FALSE for a few seconds after you open the driver until the driver has taken a reading from the specified channel port specifies which serial port the ADC 16 is attached to channel should be 1 for channel 1 2 for channel 2 et cetera adcl6_get_filtered_value short int adcl6_get_filtered_value long far value unsigned short int port short int channel This routine sets value to the filtered value for the specified channel The filtered value is scaled at filter_factor times the ADC value adc16_get_version short int adcl6_get_v
4. ADC16 Manual v1 0 1 Introduction 2 Connecting to PC PicoLog Manual Software 3 Specifications TR DataLogging software updates 4 Technical Information Writing you own software overview LENA i a UKs UKs Pan l Tel ae D C Turbo C C Delphi Vis al Excel HP Vee LabView Direct Java Pascal Win Basic Control Palm Linux Pilots eo ace WB rt G Contact Pico Technical Support Signal Legal Print this manual Conditioners Technical Information Analog connector Pin connections Scaling Converting from ADC counts to volts Serial port configurations IRQs etc Serial connection Pin connections Serial protocol Information to help develop your own driver Conversion times Conversion time vs resolution Modem operation Using with telephone and radio modems Using USB ports Using USB serial ports Safety Warning The ground input of the ADC 16 is connected directly to the ground of your computer in order to minimise electrical interference Do not connect the ground input of the ADC to anything which may be at some voltage other than ground as you may risk damage to the ADC and your computer Furthermore if you connect the ADC ground to something which is live your computer chassis may become live If in doubt check by connecting a channel input to the doubtful ground point and check that there is no significant AC or DC voltage Introduction The PICO ADC 16 is a self contained high accuracy data logger
5. as tested using HP Vee version 5 under Windows 95 The example shows how to collect a readings continuously from the adc 16 Java This example was written by Gatespace AB and all documentation and the adc jar class is found in the drivers win32 directory The example is supplied compressed as javaadc tgz Palm Pilots This example is a basic driver that reads voltages from the ADC 16 The driver has been tested with the following Palm Pilots US Robotics Palm Profesional Palm 3 Palm V Vx Palm 3c The file adc16 zip is located in the drivers win32 directory Further information can be found at http www picotech com applications palm html It should be noted that due to the power limitations with the Palm Pilot it is necessary to construct a power adapter to power the ADC 16 A suggested design for the power adapter is VIN VOUT To TCAs RH 2 TH S3 ADCL PT1 To Palm LINUX See the adc16 tar file for more information Serial port configurations Serial drivers need to know two things about a serial port in order to operate the port correctly its base address and its interrupt number IRQ Most PCs have two serial ports fitted COM1 and COM2 all software works correctly when just these ports are fitted There is also de facto standard for two more serial ports COM3 and COM4 The addresses of these ports are unique but the IRQ numbers are the same as for COM1 and COM2 COMI i C E E Some serial po
6. be sent as hex 2B 85 Al On receipt of a control byte containing a valid version request the ADC 16 will respond immediately with the version details in the following format ADC type 16 hex 10 Conversion times The ADC 16 s conversion time is affected by both the resolution and the applied voltage The figures listed below are worst case for each resolution If a severe overload is applied to the input of the ADC 16 it will shut itself down no further communication with the ADC 16 will be possible until approximately 1 second after the overload is removed Resolution bits Modem operation The ADC 16 is normally connected directly to the computer but it is also possible to access the ADC 16 via a modem using the Windows driver It is necessary to provide power to the ADC 16 either by instructing the modem to provide power or by connecting a power supply directly to the ADC 16 See serial connections for information For some radio modems there is a delay between sending text to the modem and its arrival at the other end and a similar delay for the response from the TC08 If for example the maximum possible delay is 150ms each way 300ms total the following text should be added to Win INI so that the driver waits longer for each response ADC16 Turnround 300
7. c16 bas It is however usually easier and more reliable to use the drivers provided Drivers are provided for the following operating systems DOS Windows 3 x Windows 95 98 ME Windows NT 2000 Once you have installed the software the DRIVERS directory contains a demo program which shows exactly how to drive the ADC 16 and an advanced driver which is easier to use and more powerful It also contains a copy of this manual as a text file See the Readme doc file in the DRIVERS directory for the filenames The advanced driver routine is supplied in three formats an object file called adcl6drv obj and Windows Dynamic Link Libraries for 16 bit and 32 bit programs called adcl1616 d11 and adc1632 d1l1 The object file uses Pascal linkage conventions and does not require any compiler run time routines it can therefore be used with most C and Pascal compilers It is necessary to link the file commdrv obj into your program when you use adc 16drv obj The Windows DLLs can be used with C C Pascal Delphi and Visual Basic programs it can also be used with programs like Microsoft Excel where the macro language is a form of Visual Basic and with the National Instruments Labview application More than one application can access the Windows DLL at the same time as long as the applications do not change the settings for channels that they are not using The following table specifies the function of each of the routines in the driver Routine Funct
8. e example ADC1632 XLS reads in 20 values from channels 1 and 2 one per second and assigns them to cells A1 B20 Delphi adcl6r dpr is a complete program which opens the driver and reads values from channel 1 The file ADC1 6m inc contains a set of procedure prototypes that you can include into your own programs Visual Basic Version 3 16 bits The DRIVERS WIN16 sub directory contains a simple Visual Basic program TC0816 mak ADC1616 MAK ADC1616 FRM Note that it is usually necessary to copy the DLL file to your windows system directory Version 4 and 5 32 bits The DRIVERS WIN32 sub directory contains the following files ADC1632 VBP ADC1632 BAS ADC1632 FRM Labview The routines described here were tested using Labview for Windows 95 version 4 0 While it is possible to access all of the driver routines described earlier it is easier to use the special Labview access routine The adc16 llb library in the DRIVERS WIN32 sub directory shows how to access this routine To use this routine copy adc16 11b and adc1632 dll to your labview user lib directory You will then see the adc16 sub vi and an example sub vi which demonstrate how to use it You can use one of these sub vis for each of the channels that you wish to measure The sub vi accepts the port 1 for COM1 and the channel 1 to 8 The sub vi returns the voltage in millivolts HP Vee The example routine adc16 vee is in the drivers win32 sub directory It w
9. ersion short int far version short int port This routine returns the version number of the ADC 16 attached to the specified port The upper byte of the version is always 16 for an ADC 16 the lower byte is the two hex digits of the version and release adcl6_get_cycle short int adcl6_get_cycle long far cycle short int port This routine returns the number conversion cycles conversions on all selected channels since the unit was opened If you wish to get a value for every conversion rather than taking values at fixed time intervals you should periodically call this routine then call adc16_get_value each time that cycle changes adc16_poll void adcl6_poll void The driver normally controls the ADC 16 using a Windows timer Some programs for example Excel macros prevent the timer from running so it is necessary to call adc16_poll periodically while you are waiting for data It is not normally necessary to call this routine for well behaved programs which let other applications service timer messages Try without first then call it if you do not appear to be getting data from the ADC 16 DOS Driver The DOS driver is supplied in two object files adcl 6drv obj and commdrv obj It can be used in both C and Pascal programs Windows 3 x Driver The windows 16 bit driver is the file ADC1616 DLL it is installed in the drivers win directory If an application is unable to find the DLL try moving the DLL to
10. for use with PCs and compatibles It is connected to the RS232 serial port requiring no external power and taking up no expansion slots You should have the following items supplied with the package e ADC16 high resolution serial port logger e Serial cable e Diskettes or CD containing the software e Installation manual Connecting to a PC To use the ADC 16 you should connect the 9 pin connector on the ADC 16 to a spare serial port on your computer using the cable provided If you have a 25 way serial port use the 9 to 25 way adapter supplied To check that the unit is working start up PicoLog for Windows Select File Select New Settings At the Recording dialog press OK At the Sampling dialog press OK Set the converter type to ADC 16 Select the COM port that you have connected the to ADC 16 Press OK At the ADC 16 channels dialog double click on CH1 Unused 10 At the Edit ADC 16 channel dialog press OK 11 Back to the ADC 16 channels dialog press OK 12 The recorder view should now display the voltage on channel 1 near OmV if nothing connected 13 Next connect a suitable voltage eg from a 1 5V battery to the channel Pin connections are marked on the ADC 16 and also listed here OONDORWND gt Specification between 8 and 16 bits plus sign software programmable 1M Ohm Operating temperature range 0 to 70 C Temperature coefficient 33ppm C 25 Way female D type 9 Way female D type to PC serial p
11. ion adc16_open_unit Open the driver to use a specified serial port s adc16_close_unit Close the port ALWAYS DO THIS Specify the resolution single ended differential and filterning for a channel channel adc16_get_filtered_value Get the filtered ADC value for this channel adc16_get_version Get the ADC 16 version number adc16_open_unit DOS version short int adcl6_open_unit short int port short int base short int irq Windows version short int adcl6_open_unit short int port This routine specifies the serial port number with an ADC 16 unit If you wish to use more than one ADC 16 you should call the routine once for each ADC 16 The port must be for COM1 2 for COM2 etc Under DOS this routine has extra parameters to specify the base address an interrupt number for the COM port For COM1 through COM4 these can be set to zero for the default base address and IRQ It is only necessary to use a non zero value for these parameters if you are using COM ports above COM4 you are using COM1 COM4 with a non standard base address or IRQ Under Windows this information is defined in your WIN INI file so it is not necessary to specify a value This routine returns TRUE if the driver successfully opens the ADC 16 adcl6_close_unit void adcl 6_close_unit unsigned short int port This routine disconnects the driver from the specified serial port If you successfully open any serial ports
12. on The information presented here is necessary only if you wish to write your own driver or to connect the ADC 16 to the PC in some unusual way for example via a radio modem The ADC 16 uses the following RS232 data lines pin connections as on ADC 16 3 TX Data from the PC to the ADC 16 2 RX Data from the ADC 16 to the PC Held at a positive voltage gt 7V to power the ADC 16 Held at a negative voltage lt 7V to power the ADC 16 The driver powers up the ADC 16 by enabling RTS and disabling DTR to provide the correct polarity power supply If these are set incorrectly no damage will occur to either PC or ADC 16 Serial Protocol About a second after powering on the ADC 16 the driver can communicate with the ADC 16 as a normal RS232 device The ADC 16 operates at 9600 baud with 1 stop bit and no parity The driver controls the ADC 16 using the following sequence 1 Switch RTS on and DTR off to provide power 2 Wait for more than 1 second for the ADC 16 to settle 3 Send an single control byte to the ADC 16 4 Wait for the 3 byte response from the ADC 16 Steps 3 and 4 are repeated for each measurement The ADC 16 signals the end of conversion by sending three bytes No data should be sent to the ADC 16 during the conversion as it may be lost or corrupted Control byte description The control byte tells the ADC 16 the information it needs to carry out a conversion It has the following format where bit
13. ort Analog connector Analog inputs are connected to the ADC 16 through the female D25 connector The connections are as follows ee a 14 25 Signal Ground Computer OV Pin 12 is a stable 5V output it is primarily intended for powering transducers such as thermistors The amount of current that can be drawn out of this pin varies between computers Almost all computers should be able to supply 1mA and most several times this If too much current is drawn from this pin the voltage will drop below 5V and the ADC 16 s operation cannot be guaranteed No attempt should be made to draw more than 10mA as permanent damage to the ADC 16 could result This means that loads of lower than 500 ohms must not be connected Similarly this pin must not be driven by external voltages Scaling As PicoLog software displays readings in volts this section is only required if you are writing your own software The ADC 16 generates readings which are in ADC counts The scaling of these values depends on the resolution In n bit mode the maximum input voltage 2 5V is represented by 27 1 and the minimum input voltage 2 5V is represented by 29 1 To convert an ADC value to a voltage multiply by 2 5 and divide by the maximum ADC value at the resolution that you are using C C E Drivers If you wish to use the ADC 16 with your own software it is possible to drive the ADC 16 directly see the example programs adc16a c adcl6a pas and ad
14. rt cards are capable of sharing an interrupt and some software is capable of driving a serial port that is sharing an interrupt but it is likely that either hardware or software cannot handle interrupt sharing If you install additional COM ports as COM3 or COM4 using the default IRQs these may interfere with devices connected to COM1 and COM2 For example an ADC 16 connected to COM3 may cause a mouse connected to COM1 not to function correclty The better quality serial port cards make it possible to use other interrrupts for example IRQ5 or IRQ10 There are no hard and fast rules about what IRQs are used by specific devices so it is necessary to study the technical information supplied with your computer and the proceed by trial and error The following table of typical IRQ usages may be helpful If you wish to use non standard IRQ values with Windows you should find the following lines in C windows system ini and modify the details to the values that you have selected COM4Base 02E8 COM4Irg 3 COM3Base 03E8 COM3Irq 4 It is possible to buy multi channel serial port cards normally four or eight channels where of the serial ports use the same interrupt There is not standards for these cards so it is likely that DOS ADC 16 drivers will not work correctly These cards are normally supplied with Windows drivers and so the ADC16 DLL should work correctly once the Windows drivers for the serial card are installed Serial Connecti
15. windows system The 16 bit driver is intended for use with all applications running under Windows 3 11 and for 16 bit applications running under Windows 95 Windows 95 98 Windows 95 98 can run both 16 bit and 32 bit applications For 16 bit applications see Windows 3 1 The windows 32 bit driver is the file ADC1632 DLL it is installed in the drivers win32 directory If an application is unable to find the DLL try moving the DLL to windows system Windows NT 2000 Most applications running under Windows NT are 32 bit applications The windows 32 bit driver is the file ADC1632 DLL it is installed in the drivers win32 directory If an application is unable to find the DLL try moving the DLL to windows system C DOS To link the driver into you program you should take the following steps include the header file adc16 h into your program If you are using an IDE include the files adcl6drv obj and commdrv obj in you project If you are using a command line compiler include the files adcl6drv obj and commdrv obj in you linkfile See adc16b c for an example of a simple DOS program which uses the drivers Windows The C example program is a generic windows application ie it does not use Borland AppExpert or Microsoft AppWizard To compile the program create a new project for an Application containing the following files adc16tes c adc16tes rc either adc1616 lib All 16 bit applications or adc1632 lib Borland 32 bit applications
16. you MUST call adc16_close _unit for each port before you exit from your program If you do not your computer may misbehave until you next reboot it adcl6_set_channel void adcl6_set_channel unsigned short int port unsigned short int channel unsigned short int resolution unsigned short int single_ended unsigned short int filter factor You should call this routine once for each channel that you would like to take readings from You can do this any time after calling adc16_driver_open It is permissible to change the settings as and when required The fewer channels are selected the more frequently these channels will be updated it takes about 1 second per active channel port specifies which serial portyou wish to define a channel for channel specifies which channel you want to set the details for It should be 1 8 for single ended or 1 3 5 7 for differential The resolution specifies the conversion accuracy it should be between 8 bits and 16 bits See appendix A for the conversion times at each resolution single_ended specifies whether to use the channel as a single ended input or to use the channel together with the next channel as a differential input single_ended FALSE is valid only for odd numbered channels The filter_factor controls the time constant of the filter Each time the driver takes a reading from this channel it updates the filtered value by adding a proportion of the difference between
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