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1. oo o ee o 1 2 Using BASIC E A ir EA AAA AAA 1 2 Using BASIC 3 0 4 0 oF 5 0 cosa ied i cae desis os FS ow hens a a 1 3 General BASIC Programming o o o 1 3 Using Pascal 2 0 2 1 3 0 3 1 OF DAL ai A AR 1 4 Writing th Program o ea oe A ee MAA AI A ea l 5 Setting Up 0 ects G ies eee aa ROS Draenor a ie A ns GAS 1 5 Calibration iia DS ASA AE SA AA 1 7 Reporting Unites a E AA AA ARA a A ARE e 1 7 Error Reporting and Handling o eee eee as 1 8 Multiple Configurations o o o ooo ooo oo 1 8 Taking Readingis eoe a E EA o OEE we E 1 9 Special Considerations in Taking ReadingS 1 14 The Pipeline ca iS OO TE AAN AA eS 1 16 Overrange Error ala EA A E 1 17 PACING EMO sor a dada da E 1 20 Interrupt Mod o cois en A RN A A A AA A Rea ee 1 21 ExtOtnal Pacing a AS AA ee ME a 1 23 Hardware Considerations o 1 23 Software Considerations th re Ge O dallas Beach Sores oe aplige iets 1 24 Applications oo tana Sa ose AAA ee a 1 24 Section 2 SUBROUTINE INFORMATION CALIBRATE fiche ge Seats US ae eos a Ee DA eee RSS 2 2 CONFIG Diem ap he nich a We we Ba a wo en Bb aes AAA 2 3 DISABLE INTRoo6 84 66639 co 464 Tenen Line coin sy Ae td tne eee a 2 6 ENABLE INTR oua ei Wie EER OE ee aria SPS eee 2 7 INIT Ss O A Oo aha oe a ae OR ae A ee ee aa 2 8 INPUT o rai RIO Ge BHD eee BIE a aay 2 9 MEAS LIB
2. Hewlett Packard products are warranted against defects in materials and workmanship For Hewlett Packard Desktop Computer Division products sold in the U S A and Canada this warranty applies for ninety 90 days from the date of delivery Hewlett Packard will at its option repair or replace equipment which proves to be defective during the warranty period This warranty includes labor parts and surface travel costs if any Equipment returned to Hewlett Packard tor repair must be shipped freight prepaid Repairs necessitated by misuse of the equipment or by hardware software or interfacing not provided by Hewlett Packard are not covered by this warranty HP warrants that its software and firmware designated by HP for use with a CPU will execute its programming instructions when properly installed on that CPU HP does not warrant that the operation of the CPU software or firmware will be uninterrupted or error free NO OTHER WARRANTY IS EXPRESSED OR IMPLIED INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE HEWLETT PACKARD SHALL NOT BE LIABLE FOR CONSEQUENTIAL DAMAGES For other countries contact your local Sales and Service Office to determine warranty terms HP 98645A Measurement Library User s Manual Q HEWLETT PACKARD HEWLETT PACKARD COMPANY 5 MANUAL PART NO 98645 90001 Roseville Networks Division E0684
3. For more information on reporting units see the description of the Config 0 call in this section and the discussion of reporting units in Section 1 of this manual SYSTEM_INIT System__init initializes all configured cards For each card it performs the same functions as the Init subroutine Syntax BASIC System_init Pascal PROCEDURE system_init 2 17 APPENDIX The Measurement Library reports errors with the messages listed on the next page The list gives the message number used the meaning of the message and the calls which can return the message On the page after that are listed the Pascal related error messages that may be returned to your BASIC program asa result of a Measurement Library subroutine call Messages Message Number 801 804 812 815 835 837 838 850 851 852 853 854 855 856 857 858 859 860 Measurement Library Messages Meaning Unsupported Model Array Too Small Name Not Configured Use of uninitialized name Illegal select code Specified card not at select code Illegal name Unsupported Gain Pace out of Range Repeat Specification Error Illegal Channel Number Not allowed in Interrupt Mode Common mode overrange Normal ADC overrange must be enabled by Config 0 Pace timing error Unsupported units Max number of names exceeded Offsets out of range card defective or calibration channel not shorted Reporting Calls Config 0 Sequ
4. Standard units Standard units are base units adjusted for gain and calibration expressed as real numbers They are in other words volts User units User units are standard units to which a user specified multiplier and offset have been applied expressed as real numbers You specify the values for the multiplier and offset in a Config__0 or Set__units subroutine call The default values for multiplier and offset yield standard unit values You might use user units to change the units of your readings or to compensate for a known offset in your readings or both For example say you were taking readings from a 4 to 20 mA current loop transmitter connected to a flow meter Say further that the range of the flow meter was from 0 to 50 gallons per minute and that you were making your voltage readings across a 250 ohm resistor That would mean that a reading of 1 0 volts corresponded to a flow rate of 0 gpm and that 5 0 volts corresponded to 50 gpm Using y mx b you can derive a multiplier of 12 5 and an offset of 12 5 and specify these as parameters to a Config O call 180 Config 0 Flow 98640A 18 1 01 No User 12 5 12 5 e Then whenever you take a reading from that current loop the result is expressed directly in gallons per minute That s a lot easier than making a conversion from standard units every time you take a voltage reading Error Reporting and Handling The Measurement Library reports errors for a variety of
5. The analogous call to Read__ channel would look like this in Pascal read_channel ADC chan volts gain pace Input is the name of the routine as used in a BASIC program in a Pascal program use Read_ channel Input was chosen for BASIC for compatibility with the HP 14751A software Note that you must be very specific when you call the Input subroutine the I must be upper case and all the other letters must be lower case otherwise there will be a conflict with the BASIC keyword INPUT The name Input doesn t work at all with Pascal another keyword conflict so Read_ channel was chosen instead Whatever the name the subroutine works the same way in either language Note that if you specify the optional parameters for gain and or pace interval they override the existing values only for the duration of the subroutine call After the call has completed the gain and pace interval parameters revert to their previous values Update 3 July 1988 l 1 9 Using the Library The operation of the Input subroutine in interrupt mode is different from its normal operation Refer to the discussion of interrupt mode later in this section for more details Sequential scan Use the Sequential__scan subroutine to take readings on all channels in sequence from a starting channel to an ending channel These readings are all taken at the same pace rate which you specify and the same gain specified by the most recent call to Config 0 or Set_
6. 98640A 18 64 01 No Standard When you want to take a reading from either type of voltage source just specify the name of the appropriate configuration in your reading call 420 Input Thermo 5 Tvolt 430 Input Flow 2 Gpm If 16 different ADC configurations are not enough for your application you can get more by re using existing names Do this by making a call to Config 0 and specifying an existing name the old configuration parameters for that name will be erased and the new parameters or their default values will replace them You will then have to re initialize the name with a call to the Init subroutine before you can use the new configuration Note that the use of different names for the same ADC card will not work in interrupt mode DO NOT ATTEMPT TO ACCESS AN ADC BY A DIFFERENT NAME DURING INTERRUPT MODE DATA TRANSFERS Taking Readings Taking readings is the whole reason for having an ADC card Now that you ve got your system configured it s time to start taking those readings All readings from the ADC card are taken by three subroutines Input Read__ channel Sequential__scan and Random__scan Here s how you use them Input read channel Use the Input or Read _ channel subroutine for taking a single reading from a channel on the ADC card Optionally you can specify a gain and a pace interval in the subroutine call A call to Input would look like this in BASIC 340 Input ADC Chan Volts
7. normal mode overrange readings The value can be either yes or no Only the first character is significant only y and Y are taken as yes all others indicate no units a string or string literal specifying the units to used to return ADC data The units can be base standard or user Only the first character is significant base binary data read directly from the ADC standard base ADClsb calibrate gain user standard multiplier offset multiplier a REAL number specifying the multiplier used with user units 2 3 CONFIG __0 offset a REAL number specifying the offset used with user units Default values select code 18 gain 1 pace 001 second report_error no units standard multiplier 1 0 offset 0 0 Discussion Config__0 establishes a link between a name which you supply and an ADC card and specifies operating parameters for that name and card Each ADC card used must be configured with a unique name You can configure the same card with several different names and parameter sets and everything will work except interrupt mode data transfers DO NOT ATTEMPT TO ACCESS AN ADC BY ANOTHER NAME DURING INTERRUPT MODE DATA TRANSFERS A maximum of 16 names may be configured into the Measurement Library software If you need more configurations names may be re used If a name is identical to an already used name all configuration parameters for the old name will be erased and the new configuration par
8. values Specify O if you want to use the default gain value gain_array in BASIC the name of an INTEGER array of gain values In Pascal a pointer to the shortint array of gain values The gain values in the array must be 1 8 64 or 512 The default gain value is the value specified in the Config_0 or Set_gain call In Pascal specify NIL if you want to use the default value Discussion The sizes of the channel pace and gain arrays need not be the same The Random__scan subroutine simply starts at the beginning of each array and uses the values in sequence After Random__scan uses the last value in an array it goes back to the beginning of the array for the next value Gain and pace values do not start over just because the channel array repeats In the general case the ith reading is taken using the following array elements Channel chan_array i mod size of chan_array Pace pace array i mod size of pace_array Gain gain_array i mod size of gain_ array Data data i Note that the data array must be large enough to hold all of the readings that will be generated by the Random __ scan call including repeats Gain and pace values specified for a Random_scan call are valid only for the duration of that call After the call has completed the gain and pace values revert to their default values If you are programming in Pascal and you want to use the default pace interval value the value that was specified in the Config
9. 2 8 2 17 input pipeline 1 14 readings 1 9 sampling speed 1 1 1 19 Analog input pipeline 1 14 1 20 Base units 1 1 1 7 1 18 2 4 2 16 BASIC common area 1 5 error handling 1 8 extensions 1 2 heap area 1 5 interrupt mode 1 19 loading the Measurement Library subroutines 1 2 1 3 Measurement Library subroutine size 1 3 parameter typing 1 3 1 7 2 5 programming 1 2 1 3 1 4 c Calibrate subroutine 1 7 2 2 Calibration 1 1 1 5 1 7 2 2 Common area 1 5 Common mode overrange condition 1 7 1 8 1 15 1 16 1 17 1 18 2 4 Configuration of ADC cards 1 5 1 8 2 3 Config__0 subroutine 1 5 1 7 1 8 1 9 1 10 1 18 1 20 2 3 Control lines IPACDA and EPCON 1 21 CSUB package 1 1 Disable __intr subroutine 1 19 2 6 Enable_intr subroutine 1 19 2 7 EPCON control line 1 21 Error handling 1 8 INDEX 1 Index Error messages A 1 Error reporting 1 8 ERRN function 1 8 ESCAPECODE function 1 8 External pacing 1 21 G Gain 1 5 1 6 2 15 H Heap area 1 5 HP 14751A package 1 1 1 9 2 1 Init subroutine 1 5 1 20 2 8 2 17 Initializing ADC card 1 5 2 8 2 17 Measurement Library 1 5 2 10 Input pipeline 1 14 1 20 Input subroutine 1 6 1 9 1 20 2 7 2 9 Interrupt mode 1 1 1 2 1 3 1 4 1 10 1 15 1 19 2 4 2 6 2 7 2 9 IPACDA control line 1 21 L Least significan bit LSB values 2 5 Loading the Measurement Library subroutines 1 2 1 3 LSB values 2 5 M
10. 3 of these readings and returns the 1 valid reading In interrupt mode Input performs only 1 read operation and returns the value that was requested two operations before it is up to your program to keep track of the progress of your readings through the pipeline For more information on interrupt mode programming refer to Section 1 of this manual Be careful of how you call the Input subroutine from BASIC use Input not INPUT or input to avoid conflict with the BASIC keyword INPUT In Pascal use Read__channel The pace interval comprises the sample time and the analog to digital conversion time for the reading Conversion takes 9 microseconds thus the sample time is the pace time minus 9 microseconds 2 9 MEAS_LIB_ INIT Meas_lib_ init initializes the global variables in the Measurement Library In a BASIC environment it also initializes the heap area Syntax BASIC Meas lib init Pascal PROCEDURE meas_lib init Discussion Your application program must call Meas lib init before it calls any other Measurement Library subroutines RANDOM_ SCAN Random__scan takes readings from channels in any order that you specify with whatever pace and gain value that you specify for each individual reading Syntax BASIC Random_scan name chan_array data_array rept pace _array gain _array Pascal PROCEDURE random_scan name str255 chan_size integer chan_array anyptr data_size integer data
11. D converter Even though the input voltages appear to be acceptable the amplifier may try to boost them out of the acceptable range In this case the programmable gain circuit tries to boost the Input voltage to 11 5 volts but the output limit of the op amp keeps the voltage from exceeding 10 volts The overrange flag O bit is set to one and the clipped voltage is sent to the A to D converter The resulting value is incorrect A to D Converter 6 6 Figure 1 6 Common mode overrange at gain greater than 1 A normal mode overrange is indicated when a reading returns the maximum possible magnitude value This is the same as clipping The maximum magnitude value depends on the units in use as follows Base 4095 all D bits set to 1 Standard 4095 Isb calibrate gain User 4095 isb calibrate gain mulitplier offset where Isb 10 4095 volts bit Note that it is not possible to tell the difference between a full scale reading and a normal mode overrange reading By default a normal mode overrange condition does not generate an error However by setting a parameter in the Config 0 call you can cause an error to be generated when a normal mode overrange occurs Common mode overranges are harder to detect than normal mode overranges since the value of the reading may appear to be correct even though an overrange has occurred For this reason common mode overranges are trapped as errors Note th
12. EPCON low 6 Hold EPCON and IPACDA low until all of the requested readings have been taken The subroutine call will return to your application program after all of the readings have completed 1 22 Using the Library The requirement in step 3 that you wait the set up time plus the pace interval assures that the first reading occurs at a more or less known time within approximately 3 microseconds after EPCON is set low and that the voltage has been sampled for at least the prescribed sample time pace interval minus 9 microseconds Combinations You can combine the above two methods of external pacing if your application requires We won t go into those combinations here we leave that as an exercise for the interested reader The methods above should give you enough information to make your combination work SECTION SUBROUTINE INFORMATION p This section gives the subroutine call syntax for the subroutines in the HP 98645A Measurement Library The subroutine calls supported by the library are Calibrate Config 0 Disable__intr Enable__intr Init Input Meas_lib_ init Random _ scan Read_ channel Sequential_ scan Set__ gain Set_ units System__ init These calls incorporate optional extensions beyond the HP 14751A Computer Aided Test Programming Package for the Model 6944A These calls do not exist in the HP 14751A package In the following subroutine descriptions these co
13. INTE 6 0548 645 00 4 OE 464g OH eee eee waa 2 10 RANDOM SCAN i roria we awe ee bw ce oa a eee 2 11 READ CHANNEL 263 2 34 2S e eae Va 2 13 SEQUENTIAL SCAN 300000000 a E a ENS A RR oe 2 14 SET GAIN lt a oe se a Se Ce wee oe E a 2 15 SET UNITS pe A AAA ee ace Sore Wie Get 2 16 SYSTEM INIT sats oe Ce RA AS AA ee Sh a 2 17 Appendix A MESSAGES Appendix B QUICK REFERENCE Update 2 December 1987 iv CONFIG_0 Config__0 sets up an HP 98640A ADC card for access by the Measurement Library subroutines Syntax BASIC Config 0 name model select_code gain pace report_error units multiplier offset Pascal PROCEDURE config O name str255 model str255 select code shortint gain shortint pace real report error str255 units str255 multiplier real offset real Parameters name a string or string literal specifying the name used by the Measurement Library software to refer to a particular ADC configuration model a string or string literal identifying the ADC card model number 98640A select_code an INTEGER giving the physical select code address of the ADC card This number is between 8 and 31 and is set by hardware switches on the card SWi switches 1 through 5 gain an INTEGER specifying the default ADC hardware gain The value must be 1 8 64 or 512 pace a REAL number defining the default pace time loaded into the pace counter This value can be from 0 000018 to 0 0
14. SQRT square root Bad argument real BCD conversion Bad argument BCD real conversion Stopped by user Unassigned CPU trap Reserved Reserved Macro parameter not 0 9 or a z Undefined macro parameter Error in I O subsystem Graphics error Ina BASIC 2 0 system you may get this error if you try to initialize an ADC card for a select code that contains no card APPENDIX QUICK REFERENCE This appendix is a quick reference guide to the Measurement Library subroutine calls We ve squeezed the call summaries into small type so that they fit onto the next page you can take that page out of this manual and hang it on your wall for quick reference BASIC programmers please note that the parameters that you pass to the Measurement Library subroutines must be properly typed integer real or string If you don t know the type of a parameter you can look it up in Section 2 of this manual CALIBRATE BASIC Calibrate name channel pace number Pascal PROCEDURE calibrate name str255 chan shortint pace real number shortint CONFIG__0 BASIC Config_0 name model select_code gain pace report_error units multiplier offset J Pascal PROCEDURE config_0 name str2S5 model str258 select_code shortint gain shortint pace real report_error str2S units str285 multiplier real offset real DISABLE__INTR BASIC Disable_intr name Pascal PROCEDURE disable_intr name str255 ENA
15. THEN 380 OFF INTR 18 390 Disable_intr ADC 400 PRINT Volts 1 8 410 STOP 420 END IF 430 RETURN 440 END Note that the order of the Enable_ intr call and the ON INTR statement is not critical Enable_ intr does not physically enable interrupts on the ADC card it only sets flags in the Measurement Library The card interrupts are physically enabled by the first Input call after Enable__intr line 150 in this example 1 20 Using the Library External Pacing You might use external pacing for ADC readings if you want to use a pace interval longer than that allowed by the Measurement Library software 0 0393336 second you want the readings to be controlled by an external event rather than by time External pacing is primarily a hardware operation It is largely controlled by two hardware control lines IPACDA internal pace disable and EPCON external pace control There s not a lot of software involvement other than making the read requests that you would normally make for an internally paced read The timing of the execution of those read requests is controlled by the hardware There s no provision in the software for controlling IPACDA and EPCON directly you ll have to build your own circuits to control them In the next several paragraphs we will look at some of the features of the hardware and software that affect external pacing and then we will see how they fit together in external pacing applications I
16. _ array anyptr rept shortint pace size integer pace_array anyptr gain_size integer gain _ array anyptr Parameters name a string or string literal specifying the ADC name assigned by the Config 0 call chan_size Pascal only an integer giving the size of the array of channel numbers chan_array in BASIC the name of an INTEGER array of channel numbers In Pascal this is a pointer to the shortint array of channel numbers The channel numbers can range from 0 to 7 data_size Pascal only an integer giving the size of the array of readings data array in BASIC the name of a REAL array to hold readings from the ADC card In Pascal this is a pointer to the real array of readings rept an INTEGER number of times to scan the channel array This number can be from 1 to 32767 the default value is 1 pace size Pascal only an integer giving the size of the array of pace interval values Specify O if you want to use the default pace value pace array in BASIC the name of a REAL array of pace interval values In Pascal this is a pointer to the real array of pace interval values The values in the array must be from 0 000018 to 0 0393336 seconds with a resolution of 600 nanoseconds The default pace value is the value specified in the Config 0 call In Pascal you must specify NIL if you want to use the default value RANDOM__SCAN gain size Pascal only an integer giving the size of the array of gain
17. allows all 16 possible ADC card configurations and a calibration run of 100 readings In both BASIC and Pascal the subroutine calls to Meas__lib__init Config__ 0 and Init do the following Meas_ lib__init initializes the Measurement Library and must be called before any other subroutines in the library are called Meas_lib_ init needs to be called only once in your program Config __0 sets up an ADC card for taking readings At a minimum you specify a name by which you will call the card and the model number of the card In addition you can specify the select code of the card its gain a pace rate for taking readings an error reporting parameter for normal mode overrange errors and the units base standard or user in which the readings will be reported Reporting units are discussed below If you do not supply these optional parameters Config __0 will supply default values Init resets an individual card disables interrupts for that card and sets the calibration array for that card to its default values Init must be used before any other calls except Meas_lib_ init Config 0 and System_ init System__init is the same as Init except that it initializes all cards that have been configured 1 5 Using the Library The set up portion of a typical BASIC program might look like this 20 COM Heapcom INTEGER Heaparea 1 1300 30 INTEGER Select code Gain 40 Name ADC 50 Mode1 98640A 60 Select_code 18 70 Gain 1 80 P
18. an ADC card Input is used in BASIC programs Read channel is used in Pascal programs Syntax BASIC Input name channel datum gain pace Pascal PROCEDURE read_channel name str255 channel shortint VAR datum real gain shortint pace real Parameters name a string or string literal specifying an ADC name assigned by the Config 0 call channel an INTEGER specifying the channel number from O to 7 to be read datum a REAL variable to hold the value of a reading gain an INTEGER specifying the hardware gain The value must be 1 8 64 or 512 If a value is not given for the gain the value specified in a Config 0 or Set_gain call is used pace a REAL variable specifying the pace interval that elapses before the reading This value must be from 0 000018 to 0 0393336 seconds with a resolution of 600 nanoseconds Discussion The reading returned by a call to Input or Read channel will be formatted according to the units specified in a previous call to Config__0 or Set__units If you specify values for gain or pace those values will be used only for the duration of this Input Read__channel call The Input subroutine operates differently in interrupt mode This involves the analog input pipeline Section 1 of this manual has more information on the pipeline For any reading it takes 3 read operations to get that reading all the way through the pipeline In normal mode the Input subroutine performs all
19. consent of Hewlett Packard Company Copyright O 1984 by HEWLETT PACKARD COMPANY ii PREFACE Purpose This manual explains how to use the HP 98645A Measurement Library It assumes that you have a working knowledge of the BASIC or Pascal language system on the HP 9000 Series 200 computers It also assumes that you are generally familiar with the HP 98640A Analog to Digital Converter card Refer to the manual for that card HP part number 98640 90001 for more information Organization This manual is organized as follows Section 1 How to use the HP 98645A Measurement Library Section 2 Alphabetical listing of Measurement Library iubroutine calls Appendix A Error messages Appendix B Quick reference guide to Measurement Library subroutine call syntax iii Section 1 USING THE LIBRARY Introduction aaa 1 1 FEU usa a a a a a es peta cecceaviaw a N Eet 1 1 Software Provided ar daa 1 2 The General ADDFOAC di as 1 2 UNE BASIC TD E aa 1 2 Using BASIC SOU a cab 1 3 General BASIC Programming oooooocoorcoccconnonenorinoscnorsonrrorconorsanccnranos 1 3 Using Pascal 2 0 2 1 0r 3 0 icccnscostcicas sens lisenssi pian Wels anicecrpeatertioenieneens 1 3 Writing the Progra ic ics 555 sa si en tain gactveadewes pai da 1 4 Setting DD A a Pa eae AS 1 5 Calibration 2c cscccessgesvastannssabntsenadinn aaner Aa LOT Reporting Units sciatic en apa voce Sa saSens nda Saeed a San dc EEA dD SaaS 1 7 Error Reporting and H
20. externally paced readings you will have to allow for the software set up time of the various subroutines The set up times in the BASIC language for the reading subroutines are Input 2 0 milliseconds Sequential scan 3 5 milliseconds 0 1 milliseconds per reading Using the Library Random_scan 3 0 milliseconds 0 4 milliseconds per reading You can use these set up times for Pascal programming as well Pascal set up times are shorter than those in BASIC so the times listed above will give you plenty of margin in your Pascal applications Applications External pacing applications divide into two general types single readings and bursts of readings Single readings The idea behind taking single externally paced readings is that you keep EPCON high until you want to take a reading set it low only long enough to take the reading and then set it high again The steps in taking a single reading are 1 Set IPACDA high IPACDA will remain high for the duration of externally paced readings 2 Set EPCON high This holds off all readings 3 Issue a call to Input read__ channel Sequential_ scan or Random __ scan 4 Wait The length of time you wait should be at least the set up time 5 When it is time to take a reading set EPCON low Keep it low for 1 to 15 microseconds then set it high again This will allow one and only one reading to be taken 6 Repeat step 5 until you have taken all the readings that you requested with the s
21. later in this section If bit 13 1 no common mode overrange condition occurred during this reading Note that the sense of this bit is negative true S SIGN If bit 12 0 the value returned for the reading is positive If bit 12 1 the value returned for the reading is negative D DATA The data bits give the 12 bit binary magnitude of the voltage read from the ADC The sign of the voltage is given by the S bit bit 12 Note that all readings taken from the ADC card by the ADC Library software are returned to your program through real number parameters This includes readings in base units Thus while the base unit readings have integer values they look like real numbers to your program until you explicitly convert them to integers Assigning them to integer variables in BASIC or using the trunc or round function in Pascal will make the conversion Update 3 July 1988 1 7 Using the Library Standard units Standard units are base units adjusted for gain and calibration expressed as rea numbers They are in other words volts User units User units are standard units to which a user specified multiplier and offset have beer applied expressed as real numbers You specify the values for the multiplier and offset in a Config or Set__units subroutine call The default values for multiplier and offset yield standard unit values You might use user units to change the units of your readings or to compensate for a known of
22. reading 4 msec per reading 1 2 2 2 0 msec pace interval one reading 1 0 msec 1 9 msec 2 2 msec 3 4 msec 0 1 msec per reading pace interval number of readings 0 3 msec per reading 1 0 msec per reading 1 5 msec per reading 1 2 msec 0 5 msec per reading pace interval number of readings 1 6 msec per reading 2 2 msec per reading 2 5 msec per reading NOTE Input BASIC and Read Channel Pascal take one reading each time they are called Refer to page 2 9 of this manual Array size limits The Measurement Library limits your maximum array size to 16 777 215 bytes That s really a hardware limit imposed by the width of the address bus on HP 9000 Series 200 and Series 300 computers At 8 bytes per reading that works out to a maximum of 2 097 150 readings from any one call to the Measurement Library hardly a severe restriction In practical terms you will be limited by the size of your physical memory long befor you run into the Measurement Library limit How your system lets you access that memory can be a different story It s no problem in a Pascal system since you can easily allocate an array large enough to take up all of your physical memory Things are a bit more subtle in BASIC however At first BASIC appears to limit you to 32767 readings from any single call to the Measurement Library since that s the largest number you can specify as an array dimension But you can excee
23. the calibration feature you must first reserve one of the channels on the card and short the Input and Input terminals on that channel to card ground Then use the Calibrate subroutine to take a specified number of readings from that channel at a specified pace rate The readings are taken at each of the gain settings and the average at each gain is saved These average readings are then used to calculate correction values for positive and negative readings at each gain setting When a subsequent reading is taken on any of the other channels the appropriate correction value is subtracted from the raw reading before conversion to standard or user units Reporting Units Reporting units come in three flavors base standard and user you specify one of these with the Config__0 or Set__units command The units are Base units Base units are in the form of a 16 bit binary integer of which twelve bits represent the magnitude of the reading Readings reported in base units are raw readings gain factors and calibration corrections are not applied to base units The format of a base unit reading is 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Pe eee eee eee ee ee ee en ee ee ee re ee ee eee IBIwlol TsS O JDIToD I DIJO OI O DIDIOI OID Hn when hn npn wo ne npn hn nw pen hn tne hn enh epee nen epee pee H where B BUSY If bit 15 1 the ADC is busy The reading is not taken and all other bits are invalid If bit 15 0 a valid reading is return
24. the card are not capable of slewing from maximum positive to maximum negative during the 9 microsecond sample period that this pace rate requires This puts an upper limit on the signal frequency component that the ADC can measure accurately at the 18 microsecond sample rate The following table shows that maximum frequency component for each gain for readings to within 1 lsb on a single channel Maximum Signal Gain Frequency Component 1 27 kHz 8 27 kHz 64 15 kHz 512 3 5 kHz Update 3 July 1988 1 20 Using the Library When more than one channel is being sampled as in Sequential__scan and Random__scan operations the speed of accurate sampling by the ADC is limited as follows Minimum Pace Time for Equivalent Maximum Gain Multichannel Scans Sampling Speed 1 50 microseconds 20000 readings per second 8 50 microseconds 20000 readings per second 64 71 microseconds 14000 readings per second 512 1000 microseconds 1000 readings per second interrupt Mode Interrupt mode operation is supported only in the BASIC language system It is NOT supported in Pascal Interrupt mode is useful when you want your program to continue execution between readings and still maintain an accurate or externally controlled pace rate There are two subroutines associated specifically with interrupt mode Enable _intr and Disable intr Appropriately enough interrupt mode is enabled by a call to Enable __intr and is disabled by a call to Disable __intr Only
25. the shorting wires at the calibration channel checked before you assume that the ADC card is defective Note that Calibrate temporarily requires 8 bytes of memory for each reading specified in the number parameter Large numbers of readings may cause errors due to not enough memory 2 2 CONFIG_0 Config__0 sets up an HP 98640A ADC card for access by the Measurement Library subroutines Syntax BASIC Config O name model select_code gain pace report_error units multiplier offset Pascal PROCEDURE config O name str255 model str255 select code shortint gain shortint pace real report_error str255 units str255 multiplier real offset real Parameters name a string or string literal specifying the name used by the Measurement Library software to refer to a particular ADC configuration model a string or string literal identifying the ADC card model number 98640A select code an INTEGER giving the physical select code address of the ADC card This number is between 8 and 31 and is set by hardware switches on the card SW1 switches 1 through 5 gain an INTEGER specifying the default ADC hardware gain The value must be 1 8 64 or 512 pace a REAL number defining the default pace time loaded into the pace counter This value can be from 0 000018 to 0 0393336 seconds with a resolution of 600 nanoseconds report_error a string or string literal enabling an error condition on
26. up BASIC 3 0 4 0 5 0 or 5 1 2 Load the BASIC 3 0 4 0 5 0 or 5 1 IO binary if you will be taking readings in interrupt mode Interrupt mode readings are discussed later in this section The IO binary is located on the BASIC Language Binary disc Insert that disc into the master drive and issue the command LOAD BIN Io 3 Load any other BASIC binaries that you need for your application For example this would be the time to load graphics routines 4 Write your BASIC program or load a previously written program into memory In the paragraphs below we will describe how to write your application program using the Measurement Library 5 Load the Measurement Library subroutines if they are not already part of the program you wrote in the previous step The subroutines are located on the Measurement Library disc Insert that disc into the master drive and issue the command LOADSUB ALL FROM MEAS _LIB3 or LOADSUB ALL FROM MEAS LIB4 or LOADSUB ALL FROM MEAS LIBS or LOADSUB ALL FROM MEASLIB42 or LOADSUB ALL FROM MEASLIBS2 as appropriate for your system Refer to the paragraphs on Software Provided above for information on which software goes with which system 6 Run your program Debug as necessary repeating steps 4 through 6 General BASIC Programming The Measurement Library subroutines add approximately 23 700 bytes to your BASIC program The INTR2__ 1 binary adds approximately 1200 bytes Note that intege
27. 0 call for the card you must specify a value of O for the pace size parameter and a value of NIL for the pace__array parameter Similarly if you want to use the default gain value specify a value of O for the gain__ size parameter and a value of NIL for the gain__array parameter The channel pace and gain arrays must be dimensioned as arrays even if they are only single valued Scalar variables can not be used READ_ CHANNEL Read __channel is the Pascal equivalent of the Input subroutine Refer to the discussion of Input earlier in this section for information on Read_ channel 2 13 SEQUENTIAL_ SCAN Sequential__scan takes readings from sequential channels on an ADC card Syntax BASIC Sequential scan name start stop pace data_array rept Pascal PROCEDURE sequential_scan name str255 start shortint stop shortint pace real data_size integer data_array anyptr rept shortint Parameters name a string or string literal specifying the ADC name assigned by the Config 0 call start an INTEGER specifying the number of the first channel to be read This number must be from 0 to 7 stop an INTEGER specifying the number of the last channel to be read This number must be from 0 to 7 and must not be less than start pace a REAL number specifying the pace interval This interval must be from 0 000018 to 0 0393336 seconds with a resolution of 600 nanoseconds data_size Pascal only an integer giving th
28. 1 7 1 8 2 16 Standard units 1 1 1 7 1 8 1 18 2 5 2 16 Subroutine calls Calibrate 1 7 2 2 Config __0 1 5 1 7 1 8 1 9 1 10 1 18 1 20 2 3 Disable__intr 1 19 2 6 Enable __intr 1 19 2 7 Init 1 5 1 20 2 8 2 17 Input 1 6 1 9 1 20 2 7 2 9 Meas_lib_ init 1 5 2 10 Random _scan 1 6 1 9 1 11 2 11 Read channel 1 6 1 9 2 9 2 13 Sequential__scan 1 6 1 9 1 10 2 14 Set_ gain 1 6 1 10 2 15 Set__units 1 6 1 7 1 8 2 16 System__init 1 5 1 20 2 17 System__init subroutine 1 5 1 20 2 17 T Try Recover mechanism 1 8 U Units 1 1 1 5 1 6 1 7 2 4 2 16 User units 1 1 1 7 1 8 1 18 2 5 2 16 INDEX 4 E HEWLETT 2B PACKARD Reorder No or Manual Part No 98645 9000 1 E0684 U0788
29. 17 B 2 Initializing ADC card 1 5 2 8 2 17 Measurement Library 1 5 2 10 Input pipeline 1 16 1 21 Input subroutine 1 6 1 9 1 21 2 7 2 9 B 2 Interrupt mode 1 1 1 2 1 3 1 4 1 10 1 17 1 21 2 4 2 6 2 7 2 9 IPACDA control line 1 23 L Least significant bit LSB values 2 5 Loading the Measurement Library subroutines 1 2 1 3 LSB values 2 5 Measurement Library features 1 1 general information 1 1 initialization 1 5 2 10 messages A 2 programming 1 2 quick reference B 1 size 1 3 1 4 software provided 1 2 subroutines 1 2 1 3 Update 2 December 1987 INDEX 2 Meas_lib_ init subroutine 1 5 2 10 B 2 Messages A 1 Multi dimensional arrays 1 15 Multiple configurations of an ADC card 1 8 1 21 2 4 2 7 Normal mode overrange condition 1 5 1 8 1 17 1 18 1 19 O ON ERROR mechanism 1 8 Overrange condition common mode 1 7 1 8 1 17 1 19 1 20 2 4 normal mode 1 5 1 8 1 17 1 18 1 19 p Pace interval 1 5 1 6 1 20 Pacing errors 1 20 Pacing external 1 23 Pascal common area 1 5 error handling 1 8 heap area 1 5 l importing the Measurement Library 1 4 interrupt mode 1 4 1 21 2 7 messages A 3 Measurement Library size 1 4 parameter passing 1 4 parameter typing 1 4 1 7 2 1 2 5 programming 1 4 1 5 Pipeline 1 16 1 21 Programming general 1 2 1 5 in BASIC 1 2 1 3 1 5 in Pascal 1 4 1 5 Q Quick reference guide B 1 Random __
30. 3 6 4 5 7 Pace 02 Gain 1 1 64 Update 3 July 1938 1 11 Using the Library In taking readings from the channels in the channel array the Random__scan subroutine will use the pace array six times and the gain array twice The call sequence to take those readings once would be in BASIC 110 INTEGER Channel 1 6 120 REAL Pace 1 1 130 INTEGER Gain 1 3 140 REAL Data 1 6 150 DATA 2 3 6 4 5 7 160 READ Channel 170 DATA 02 180 READ Pace 190 DATA 1 1 64 200 READ Gain 320 Repeat 1 330 Random_scan ADC Channel Data Repeat Pace Gain Update 3 July 1988 1 12 In Pascal the sequence would be CON e start stop 7 rept 1 d size 6 p_size 1 g size 3 c size 6 ST name ADC 23 TYPE r_array ARRAY 1 6 OF real VAR r_ptr r_array i_array ARRAY 1 6 OF shortint i ptr i array data r_ptr channel i_ptr pace r_ptr gain i ptr new channel channel 1 channe1 2 channe1 3 channe1 4 channe1 5 channe1 6 new pace pace 1 0 02 new gain gain 1 1 gain 2 1 gain 3 N A WHRAeAH nO DH W P we y y we we ee ee ee ee ee oe oe new data random_sc n name c_size channel d size data rept p_size pace g_size gain Using the Library Update 3 July 1988 1 13 Using the Library In the general case the ith reading is taken using the fo
31. 393336 seconds with a resolution of 600 nanoseconds report_error a string or string literal enabling an error condition on normal mode overrange readings The value can be either yes or no Only the first character is significant only y and Y are taken as yes all others indicate no units a string or string literal specifying the units to used to return ADC data The units can be base standard or user Only the first character is significant base binary data read directly from the ADC standard base ADClsb calibrate gain user standard multiplier offset multiplier a REAL number specifying the multiplier used with user units CONFIG_0 offset a REAL number specifying the offset used with user units Default values select_code 18 gain pace 001 second report_error no units standa rd multiplier 1 0 offset 0 0 Discussion Config__0 establishes a link between a name which you supply and an ADC card and specifies operating parameters for that name and card Each ADC card used must be configured with a unique name You can configure the same card with several different names and parameter sets and everything will work except interrupt mode data transfers DO NOT ATTEMPT TO ACCESS AN ADC BY aonnen NAME DURING INTERRUPT MODE DATA TRANSFERS A maximum of 16 names may y be contigund into the Measurement Library software If you need more configurations names may be re used If a name is ide
32. 8000 Foothills Boulevard Printed in U S A Roseville California 95678 June 1984 PRINTING HISTORY The Printing History below identifies the Edition of this Manual and any Updates that are included Periodically update packages are distributed which contain replacement pages to be merged into the manual including an updated copy of this Printing History page Also the update may contain write in instructions Each reprinting of this manual will incorporate all past updates however no new information will be added Thus the reprinted copy will be identical in content to prior printings of the same edition with the user inserted update information New editions of this manual will contain new information as well as updates pos First Edition ida June 1984 NOTICE The information contained in this document is subject to change without notice HEWLETT PACKARD MAKES NO WARRANTY OF ANY KIND WITH REGARD TO THIS MATERIAL INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE Hewlett Packard shall not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing performance or use of this material This document contains proprietary information which is protected by copyright All rights are reserved No part of this document may be photocopied reproduced or translated to another language without the prior written
33. BLE__INTR BASIC Enable_intr name Pascal PROCEDURE enable_intr name str2SS INIT BASIC Init name Pascal PROCEDURE init name str255 INPUT READ_ CHANNEL BASIC Input name channel datum gain pace Pascal PROCEDURE read_channel name str255 channel shortint VAR datum real gain shortint pace real MEAS __LIB_ INIT BASIC Meas_lib_init Pascal PROCEDURE meas_lib_init RANDOM_ SCAN BASIC Random_scan name chan_array data_array rept pace_array gain_array Pascal PROCEDURE random_scan name str25S chan_size integer chan_array anyptr data_size integer data array enyptr rept shortint pace_size integer pace_array anyptr gain_size integer gain_array anyptr SEQUENTIAL__SCAN BASIC Sequential_scan name start stop pace data_array rept Pascal PROCEDURE sequential_scan name str255 start shortint stop shortint pace real data_size integer data_array anyptr rept shortint SET__GAIN BASIC Set_gain name gain Pascal PROCEDURE set_gain name str2 5 gain shortint SET__UNITS BASIC Set_units name units multiplier offset Pascal PROCEDURE set_units name str2SS units str255 multiplier real offset real SYSTEM_ INIT BASIC System_init Pascal PROCEDURE system_init A ADC card calibration 1 7 configuration 1 5 1 8 2 3 configurations multiple 1 8 1 20 2 4 2 7 initialization 1 5
34. Note that the after each file name is significant The procedure calls for the Measurement Library are all exported from the file MEAS__LIB CODE or MEAS _ LIB3 CODE along with the following types TYPE shortint 32768 32767 byte 0 255 etr255 string 255 jarraytype ARRAY O maxint OF shortint rarraytype ARRAY O maxint OF real rarraypt rarraytype jarraypt iarraytype Due to the rigorous structure of the Pascal language you can t default parameters in the procedure calls However to save you the bother of declaring real and integer arrays for the pace and gain array parameters of the random__scan procedure you can use the default pace or gain value established by a call to Config _0 or Set__gain by specifying a O for the array size and a NIL for the array pointer All other parameters for all procedure calls must be explicitly provided in the procedure call as real integer or shortint or string variables or as constants or literal constants For all array parameters make sure that the array elements are of the correct type real or shortint do not substitute integer for shortint And take care that the size parameter you pass for an array does not exceed the actual size you declared for that array If you exceed the declared array size you can write all over the other variables in your program and cause yourself much anguish Once your Pascal program has been written and compiled it must be mer
35. ON pulses should be at least 36 milliseconds apart if you re operating in interrupt mode Update 3 July 1988 1 24 Using the Library Bursts of Readings The idea behind taking readings in bursts is that you request multiple readings with a subroutine call and then take those readings in one burst by setting EPCON low until all of the readings have been taken These readings can be taken at the free run speed of the card or they can be paced by the card s internal pacing timer The following steps are for triggering burst readings that are paced by the internal pacing timer 1 2 3 4 6 Set IPACDA and EPCON high Make a read request by issuing a call to Sequential__scan or Random__scan Wait You should wait for at least the set up time plus the pace interval Set the EPCON line low The analog to digital conversion for the first reading will start in approximately 3 microseconds Set the IPACDA line low This must happen 1 to 15 microseconds after you set EPCON low Hold EPCON and IPACDA low until all of the requested readings have been taken The subroutine call will return to your application program after all of the readings have completed The requirement in step 3 that you wait the set up time plus the pace interval assures that the first reading occurs at a more or less known time within approximately 3 microseconds after EPCON is set low and that the voltage has been sampled for at least the prescri
36. Up in Section 1 of this manual for a full discussion of ADC card configuration 2 5 DISABLE__INTR Disable__intr configures the ADC card for normal non interrupt mode operation Syntax BASIC Disable_intr name Pascal PROCEDURE disable intr name str255 Parameter name a string or string literal specifying the ADC name assigned by the Config_0 call Discussion Interrupt mode operation is supported only for BASIC environments Use of interrupt mode in Pascal is not supported Please refer to the discussion of the Enable intr subroutine next page for further information ENABLE_INTR Enable__intr configures an ADC card for interrupt mode operation Syntax BASIC Enable intr name Pascal PROCEDURE enable _intr name str255 Parameter name a string or string literal specifying the ADC name assigned by the Config 0 call Discussion Interrupt mode operation is not supported in the Pascal environment That means you re on your own if you use it If you have trouble making it work you can purchase HP consulting on a time and materials basis from your local HP sales and service office HP sales and service offices are listed in the back of this manual For interrupt mode to work in Pascal you need to have an appropriate interrupt service routine ISR If you use interrupt mode without one you will probably crash your system We don t provide an ISR as part of the Measurement Library but if you re a skilled P
37. _gain and the values are returned to a data array Optionally you can repeat the readings as many times as you want For example if you wanted to take readings from channels 2 through 7 on an ADC card at the same gain and pace rate Sequential_ scan would be the appropriate subroutine to use In BASIC 100 110 230 240 250 260 270 460 In Pascal e CONST TYPE VAR e INTEGER Start Stop Repeat REAL Data 1 6 Name ADC Start 2 Stop 7 Pace 0 01 Rept 1 Sequential_scan Name Start Stop Pace Data Rept name ADC pace 0 01 start 2 stop E rept 1 d_size 6 d_array ARRAY 1 6 OF real d_ptr d array data d_ptr new data sequential scan name start stop pace d size data rept Update 3 July 1988 1 10 Using the Library You must make sure that your data array is large enough to hold all of the readings that the Sequential__scan call will generate Note that if the call to Sequential_ scan aborts the contents of the array will be undefined This is because the Sequential_ scan subroutine uses the array space as temporary storage for a variety of nasty messy variables it doesn t fill the array with nice clean data until just before it returns to your program If the subroutine aborts while the array space is filled with garbage and your program tries to interpret the garbage as data you may not be pleased with the results The pace interval that you
38. a limited subset of Measurement Library subroutine calls are allowed after you have entered interrupt mode Input Config_0 Init System __ init Disable __intr Use of any other Measurement Library calls in interrupt mode will result in an error When you are in interrupt mode the Measurement Library does not automatically take care of setting up and clearing out the input pipeline Refer to the description of the analog input pipeline earlier in this section Thus when you take a reading with the Input subroutine the result you get is the value of the reading taken two readings ago You should discard the data returned from the first two Input calls Interrupt mode does not handle multiple configurations of the same card cleanly To avoid taking erroneous readings do not take readings from different configurations names for the same card while in interrupt mode The shortest pacing interval usable in an interrupt mode application is dependent upon many factors The main factors are the speed of the CPU executing the BASIC program and the type of BASIC program instructions that are being executed while the ADC is taking readings To properly understand these factors it is important to understand how the BASIC operating system services interrupts When BASIC has been enabled to service interrupts for a specific select code with an ON INTR sc priority GOSUB label statement and an interrupt occurs on that select code BASIC logs the fact
39. ace 0 01 90 Error No 100 Unit Standard 220 Meas_lib init 230 Config 0 Name Model Select_code Gain Pace Error Unit 240 Init Name The analogous Pascal code would look like this e CONST name ADC model 98640A select code 18 gain 1 pace 0 01 error NO units STANDARD multiplier 1 0 offset 0 0 BEGIN meas_lib init config 0 name model select_code gain pace error units multiplier offset init name i The most frequently used configuration parameters can be reset without reconfiguring the card these parameters are gain pace interval and units The gain can be reset with a call to the Set_gain subroutine or a new gain can be specified as a parameter to the Input or Random__scan subroutine The Input and Random__scan subroutines are used to take voltage readings from the ADC they are described later in this section A new pacing interval can be specified as a parameter to the Input Sequential__scan or Random__scan subroutine And the units can be reset with a call to the Set__units subroutine Note that if you specify pace or gain parameters in an Input Sequential_scan or Random__scan call the specified pace or gain value holds only for the duration of the call it reverts to its previous value after the call completes 1 6 Using the Library Calibration Calibration gives you a way of compensating for offsets that are inherent to the ADC card To use
40. acing timer of the card is used if IPACDA is high the internal pacing timer is bypassed and readings are taken at the free run speed of the card one reading every 18 microseconds Note that IPACDA must be high when readings start in order for the timing of the first _ reading of a series to be accurately known IPACDA can be set low after the start of readings if you want the readings to be paced by the internal pacing timer EPCON controls whether or not any readings are taken If EPCON is low readings are taken whenever they are requested If EPCON is high requested readings are held off a read request will not complete until EPCON goes low again In summary when EPCON is low readings are taken at the free run speed of the card if IPACDA is high or at the time programmed into the internal pacing timer if IPACDA is low When EPCON is high readings stop Update 3 July 1988 1 23 Using the Library Software Considerations When making externally paced readings you will have to allow for the software set up time of the various subroutines The set up times in the BASIC language for the reading subroutines are Input 2 0 milliseconds Sequential scan 3 5 milliseconds 0 1 milliseconds per reading Random_scan 3 0 milliseconds 0 4 milliseconds per reading Set up times in Pascal are Read_ channel 2 0 milliseconds Sequential scan 3 4 milliseconds 0 1 milliseconds per reading Random_scan 1 2 milliseconds 0 5 millis
41. alue for one reading is being returned the voltage for the next reading is being latched and converted and the channel address is being provided for the reading after that For example during time period t3 in the figure below the first reading is taken from the card while the second reading is being converted and the third address is being supplied address 1 convert 1 1 b enn e mm m o m m AA address 2 il return 2 her EA q horca convert 3 return 3 i Pr o o e es 0 a 0 0 00 9 ee address 4 convert 4 return 4 Hp oe ee meme horno porn t1 t2 t4 t5 t6 A A e alc gt Figure 1 2 Analog Input Pipeline To start the flow of readings the Measurement Library software primes the pipeline by taking two garbage readings at times ti and t2 in the figure above these two readings are thrown away Their only purpose was to start pulling valid readings through the pipeline The third reading taken is the first valid reading since it is the first reading that has gone through all three stages of the pipeline it is written into the data array as the first reading For all readings taken in normal mode the Measurement Library software takes care of priming and emptying the pipeline it does this by taking two more readings than are requested and throwing away the Update 3 July 1988 1 16 Using the Library two extra garbage values This happens for each subroutine call you never have to pay an
42. ameters or defaults will be used The name will then have to be reinitialized with Init before it is accessed All readings taken by the ADC are reported in one of three reporting units base standard or user Base units are in the form of a 16 bit binary integer with the following format 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Han nba nha nn pn nnn pn a e e e penn to pe tee nt 1BI wlo sS DIDIDIDIOITDITOJODIOIJo DIDI Hn pn hn pn nn hn pan npn nn pn hn nn en he npn ent enn pen ete ent MSB LSB where B BUSY If bit 15 1 the ADC is busy The reading is not taken and all other bits are invalid If bit 15 0 a valid reading is returned W WAIT If bit 14 1 the ADC card was in the wait state at the time of the reading This means that the card was not read within the interval specified in the pacing timer that is a paced read was not made at the correct time You should never see this bit set since the ADC Library software reports an incorrectly paced read as an error and will not return a value for the reading O OVERRANGE If bit 13 0 a common mode overrange condition occurred during this reading and the reading is invalid If bit 13 1 no common mode overrange condition occurred during this reading Note that the sense of this bit is negative true S SIGN If bit 12 0 the value returned for the reading is positive If bit 12 1 the value returned for the reading is negative CONFIG 0 D DATA The d
43. amplifiers op amps and are then sent to an analog to digital A to D converter for conversion to a numeric value The figures below show this circuit configured for a gain of 1 There are a couple of limitations that apply to this measurement circuit 1 The voltage output from an input op amp can not exceed 10 volts relative to system ground Fora gain of 1 this also means that the input voltage applied to the op amp can not exceed 10 volts again relative to system ground The situation gets rather more complicated for gains greater than one the formula for figuring the maximum input voltage is somewhat abstruse involving various voltages gains and a couple of 2s We won t get into the mathematics of it but figure 1 6 shows an example of the results that you may see Exceeding this input limit causes a common mode overrange the output of the op amp is clipped at its limit 10 volts or 10 volts and the overrange flag the O bit in a base unit reading is set to 1 2 The A to D converter which compares the outputs of the op amps can not measure a difference of more than 10 volts If the difference between those outputs is more than 10 volts the A to D converter clips its output value to 10 volts this situation is defined as a normal mode overrange The next few figures show various combinations of input voltages and the outputs they produce In the figures Input and Input voltages relative to system ground are shown in
44. and pace values do not start over just because the channel array repeats For example consider an ADC card that has flowmeters attached to channels 2 3 4 and 5 and thermocouples attached to channels 6 and 7 Say that you wanted to take the id sets of readings Channel 2 3 6 4 5 7 Pace 02 02 02 02 02 02 Gain 1 1 64 1 1 64 To take these readings you could set up the following arrays Channel 2 3 6 4 5 7 Pace 02 Gain 1 1 64 Using the Library In taking readings from the channels in the channel array the Random__scan subroutine will use the pace array six times and the gain array twice The call sequence to take those readings once would be in BASIC e 110 INTEGER Channel 1 6 120 REAL Pace 1 1 130 INTEGER Gain 1 3 140 REAL Data 1 6 150 DATA 2 3 4 5 6 7 160 READ Channel 170 DATA 02 180 READ Pace 190 DATA 1 1 64 200 READ Gain 320 Repeat 1 330 Random_scan ADC Channel Data Repeat Pace Gain In Pascal the sequence would be CONST name TYPE VAR we Nn gt 3 start stop rept d_size p_size g_size c_size 4 tf a ye wo we we we we O WwW 0 r_array ARRAY 1 6 OF real r_ptr r_array i array ARRAY 1 6 OF shortint i_ptr i array data r_ptr channel i_ptr pace r_ptr gain i ptr new channel channel 1 channel 2 channel 3 channel 4 channel 5 channel 6 nou
45. andling ccccccecseccccceccccecccesecnccessceacecesees 1 8 Multiple Configurations cccccccsccccncccecccccsessncecceecesscecessenseesece 1 8 Taking RESIDE oss csiscs ssa cc suka naiesashnvinc usa Lawoeawelaca tu aiee bea weasiasaeeaewiusees 1 9 TRE PIPE ae cas edn cue Seite we caer acer an 1 14 Overta nge Brrorsoceces ci inieckicctarawsn tts tlie ee EA eed ses 1 15 Pacing Errors os ps hel cde was ac tac e a ias 1 19 INTELTUDE MOTES ssc dessdeeiva ciancadniaesaeida ccs eesaasessaaaywe nase ens Eeoae Erer EE 1 19 EXTERNAL PACIEN Ro 1 21 Hardware Considerations ccccccccccccccccesccescnceccceceescsseecesenseececenes 1 21 Software Considerations cccccccccccsccccnccceecscstescesesccsccesteensesesseas 1 21 Applications iiss as eL Section 2 SUBROUTINE INFORMATION CALIBRATE isis seesies Sos oak Sess ii iw he a eas Ua cased eae 2 2 CONFIO Oras etce wince se dane ue ia val a a even relent e Paves eee aE E eaa 2 3 DISABLE INTRO EN ah 2 6 ENABLE INTR unas eSTAT SEEEN aves en ele odes 2 7 INIT a A a a cet has ow wae Re wae a A ese a eee 2 8 INP UE A A IA Na 2 9 MEAS LIB INT usa AS 2 10 RANDOM SCAN Sid dia 2 11 READ CHANNEL cia ad 2 13 SEQUENTIAL SCAN Sa Ni 2 14 SET GAIN unn a a ES 2 15 SET UNITS ia a aea 2 16 SYSTEM INT as 2 17 Appendix A MESSAGES Appendix B QUICK REFERENCE CONTENTS iv SECTION USING THE LIBRARY B INTRODUCTION The HP 98645A Meas
46. are adapted to the BASIC language with the CSUB utility package The Measurement Library is compatible with BASIC 2 0 2 1 3 0 4 0 5 0 5 1 and Pascal 2 0 2 1 3 0 3 1 3 2 The Measurement Library subroutine calls are a superset of the HP 14751A Computer Aided Test Programming Package for the Model 6944A BASIC programs written using the HP 14751A routines should be able to use the Measurement Library software with very little modification Features The HP 98645A Measurement Library allows you to Take a single reading from any of 8 channels at any of 4 gains Take readings by scanning across 1 to 8 channels any number of times Take readings from channels in random order as specified in an address array Optionally you can specify the gain and pace interval for each reading and the readings can be repeated any number of times Express readings in three different units Base units binary integer returned from the ADC Standard units base units adjusted for gain and calibration expressed as real numbers User units standard units times a user multiplier plus a user offset Take calibration zero readings on a specified channel and apply that calibration adjustment to all readings Re set gain or units at any time Take readings at the full 55 kHz sampling speed of the ADC card from either BASIC or Pascal Take readings under interr pt mode in BASIC Update 3 July 1988 1 1 Using the Library Software Provided T
47. ascal programmer you may be able to write one of your own Refer to the Pascal 2 0 System Designer s Guide part number 09826 90074 for more information on ISRs Interrupt mode does work in BASIC There are a few things you should be aware of 1 The only Measurement Library calls allowed after an Enable__interrupt call are Input Config 0 Init System_ init Disable __interrupt 2 The Input subroutine functions differently in interrupt mode Refer to the description of that subroutine later in this section for more information 3 Interrupt mode does not handle multiple configurations of the same ADC card well To prevent erroneous readings do not try to take readings from different configurations names of the same ADC card while in interrupt mode For a more complete explanation of interrupt mode programming refer to Section 1 of this manual INIT Init resets and disables interrupt mode on an ADC card and sets the calibration array to its default values Syntax BASIC Init name Pascal PROCEDURE init name str255 Parameter name a string or string literal specifying an ADC name assigned by the Config_0 call Discussion The Init initialize call must be used prior to any other calls except Config Oand System_init A single call to System__init may be substituted for individual Init calls for all currently configured cards INPUT The Input or Read__channel subroutine takes one reading from a specified channel on
48. at the Measurement Library reports errors for normal mode and common mode overranges only when you are operating in standard or user units If you are operating in base units no error will be reported To detect a normal mode overrange in base units check the D bits for a full scale reading to detect a common mode overrange check the O bit Using the Library Pacing Errors The pace counter on the ADC card is used to determine the duration of the sample portion of the sample and hold cycle The hold portion is always 9 microseconds and the minimum sample portion is 9 microseconds The Measurement Library lets you specify a pace interval that is the sum of these two time periods Thus you can set the pace at which readings are taken for ease in making accurate time domain measurements of time varying quantities If due to outside factors concurrent I O transfers keyboard interrupts and so on the Measurement Library software is unable to read from the ADC card fast enough to keep up with a programmed pace time a pacing error will occur This gives you the assurance that in the absence of such errors the time domain measurements are being accurately paced While the ADC card and the Measurement Library are fully capable of taking readings every 18 microseconds the variable gain input amplifiers on the card are not capable of slewing from maximum positive to maximum negative during the 9 microsecond sample period that this pace rate require
49. ata bits give the 12 bit binary magnitude of the voltage read from the ADC The sign of the voltage is given by the S bit bit 12 MSB most significant bit LSB least significant bit Base unit readings are raw readings no gain factors or calibration corrections are applied The value used by the Measurement Library for the ADC card least significant bit ADCIsb is the 64 bit floating point value of 10 volts 4095 bits or 2 442002442002442 millivolts per bit The least significant bit LSB values used in each gain range are LSB ADCIsb gain Thus the approximate LSB values in each gain range are Gain LSB 1 2 4420 millivolts 8 305 25 microvolts 64 38 156 microvolts 512 4 7695 microvolts Standard units are real numbers representing true volts They are equivalent to base unit values corrected for gain and calibration if any User units are real numbers equivalent to standard units times a multiplier plus an offset ADC readings are always returned from the Measurement Library calls as real numbers or real array elements IEEE 64 bit floating point binary representation in both BASIC and Pascal Readings in standard or user units should be stored and manipulated as real numbers Readings in base units must be converted into integer format by the user program prior to any manipulation of the data Assignment to an integer variable in BASIC or using the trunc or round function in Pascal will suffice Refer to Setting
50. be reset without reconfiguring the card these parameters are gain pace interval and units The gain can be reset with a call to the Set_ gain subroutine or a new gain can be specified as a parameter to the Input or Random_ scan subroutine The Input and Random__scan subroutines are used to take voltage readings from the ADC they are described later in this section A new pacing interval can be specified as a parameter to the Input Sequential_ scan or Random__scan subroutine And the units can be reset with a call to the Set__units subroutine Note that if you specify pace or gain parameters in an Input Sequential_scan or Random __scan call the specified pace or gain value holds only for the duration of the call it reverts to its previous value after the call completes Update 3 July 1988 1 6 Using the Library Calibration Calibration gives you a way of compensating for offsets that are inherent to the ADC card To use the calibration feature you must first reserve one of the channels on the card and short the Input and Input terminals on that channel to card ground Then use the Calibrate subroutine to take a specified number of readings from that channel at a specified pace rate The readings are taken at each of the gain settings and the average at each gain is saved These average readings are then used to calculate correction values for positive and negative readings at each gain setting When a subsequent reading is taken o
51. bed sample time pace interval minus 9 microseconds Combinations You can combine the above two methods of external pacing if your application requires We won t go into those combinations here we leave that as an exercise for the interested reader The methods above should give you enough inf ormation to make your combination work Update 3 July 1988 1 25 The following pages are replacement pages from the previous update Pages superseded by the current update are not included a PREFACE Purpose This manual explains how to use the HP 98645A Measurement Library It assumes that you have a working knowledge of the BASIC or Pascal language system on the HP 9000 Series 200 or Series 300 computers It also assumes that you are generally familiar with the HP 98640A Analog to Digital Converter card Refer to the manual for that card HP part number 98640 90001 for more information Organization This manual is organized as follows Section 1 How to use the HP 98645A Measurement Library Section 2 Alphabetical listing of Measurement Library subroutine calls Appendix A Error messages Appendix B Quick reference guide to Measurement Library subroutine call syntax Update 1 November 1985 iit CONTENTS Section 1 USING THE LIBRARY Introduction isa sn de it da BRO De RH A Ge SE OE SY 1 1 Features ooo da a A A A ta SE 1 1 Software Provided ici ESA A a EAS 1 2 The General Approach
52. broutine permanently overrides the gain set by a previous call to Config __0 or Set__gain The description of the Config__0 subroutine in this section discusses the Isb values for each gain setting 2 15 SET_ UNITS Set__units sets the reporting units for readings taken by the Measurement Library subroutines These units are base standard or user units Syntax BASIC set_units name units multiplier offset Pascal PROCEDURE set_units name str255 units str255 multiplier real offset real Parameters name a string or string literal specifying the ADC name assigned by the Config_0 call units a string or string literal specifying the units to be used to return ADC data The units must be base standard or user Only the first character is significant multiplier user units only a REAL number specifying the multiplier to be used See the discussion below This parameter is not used with base or standard units offset user units only a REAL number specifying the offset to be used See the discussion below This parameter is not used with base or standard units Discussion The three types of units are defined as base raw ADC reading returned as a binary integer standard base unit reading adjusted for gain and calibration expressed as a real number user standard multiplier offset Set__ units permanently overrides any previous units specification made by a Config__0 or Set__units call
53. ce the value of the reading may appear to be correct even though an overrange has occurred For this reason common mode overranges are trapped as errors Note that the Measurement Library reports errors for normal mode and common mode overranges only when you are operating in standard or user units If you are operating in base units no error will be reported To detect a normal mode overrange in base units check the D bits for a full scale reading to detect a common mode overrange check the O bit Pacing Errors The pace counter on the ADC card is used to determine the duration of the sample portion of the sample and hold cycle The hold portion is always 9 microseconds and the minimum sample portion is 9 microseconds The Measurement Library lets you specify a pace interval that is the sum of these two time periods Thus you can set the pace at which readings are taken for ease in making accurate time domain measurements of time varying quantities If due to outside factors concurrent I O transfers keyboard interrupts and so on the Measurement Library software is unable to read from the ADC card fast enough to keep up with a programmed pace time a pacing error will occur This gives you the assurance that in the absence of such errors the time domain measurements are being accurately paced While the ADC card and the Measurement Library are fully capable of taking readings every 18 microseconds the variable gain input amplifiers on
54. cess a reading sequence The total time required is the sum of item a item b and the appropriate value from item c Note that these are worst case values You would get these values from Series 200 computers using an 8 MHz MC68000 processor chip and no floating point math card Processing times will be shorter for computers with later faster processor chips and or floating point math cards BASIC Input Set up time 2 0 msec b Read time pace interval one reading t c Data conversion time BASE units 1 0 msec STANDARD units 1 9 msec USER units 2 5 msec Sequential scan 7 a Set up time 3 5 msec 0 1 msec per reading b Read time pace interval number of readings c Data conversion time BASE units 0 3 msec per reading STANDARD units 1 2 msec per reading USER units 1 5 msec per reading Update 3 July 1988 1 14 Random scan a Set up time b Read time c Data conversion time BASE units STANDARD units USER units PASCAL Read channel a Set up time b Read time c Data conversion time BASE units STANDARD units USER units Sequential scan a Set up time b Read time c Data conversion time BASE units STANDARD units USER units Random scan a Set up time b Read time c Data conversion time BASE units STANDARD units USER units Using the Library 3 0 msec 0 4 msec per reading pace interval number of readings 3 msec per reading 2 msec per
55. d Now that you ve got your system configured it s time to start taking those readings All readings from the ADC card are taken by three subroutines Input Read__channel Sequential_ scan and Random__scan Here s how you use them Input read channel Use the Input or Read__channel subroutine for taking a single reading from a channel on the ADC card Optionally you can specify a gain and a pace interval in the subroutine call A call to Input would look like this in BASIC 340 Input ADC Chan Volts The analogous call to Read__ channel would look like this in Pascal read_channel ADC chan volts gain pace Input is the name of the routine as used in a BASIC program in a Pascal program use Read__ channel Input was chosen for BASIC for compatibility with the HP 14751A software Note that you must be very specific when you call the Input subroutine the I must be upper case and all the other letters must be lower case otherwise there will be a conflict with the BASIC keyword INPUT The name Input doesn t work at all with Pascal another keyword conflict so Read_channel was chosen instead Whatever the name the subroutine works the same way in either language 1 9 Using the Library Note that if you specify the optional parameters for gain and or pace interval they override the existing values only for the duration of the subroutine call After the call has completed the gain and pace interval parameters revert to their prev
56. d that number of readings by using a multi dimensional array You can easily fill up all the memory you have using a two dimensional array BASIC allows you up to six dimensions in your arrays so you can arrange your data in whatever format is convenient The Measurement Library doesn t care if your array is multi dimensional all it wants is the starting address of the array which you supply by passing the name of the array in the subroutine call The only thing you have to take care of is reading your data out of the multi dimensional array in the correct order Update 3 July 1988 1 15 Using the Library Note that the ability to specify large data arrays does NOT constitute a continuous data acquisition CDA scheme The amount of data you can collect with the Measurement Library subrcutines is limited by the amount of memory in your computer The Measurement Library has no provision for say logging high speed data to a disc for indefinite periods without missing readings The Pipeline The ADC requires three operations to produce a reading 1 provide the channel address for the reading 2 latch the voltage and convert it to a digital value 3 return the value to the host computer For any given reading these three operations must be done serially hon porn horno address convert return Figure 1 1 Analog input operation However to maximize throughput the ADC card pipelines the readings That is while the v
57. e a string or string literal specifying the ADC name from the Config 0 call channel an INTEGER specifying the reference channel from 0 to 7 to be used for calibration pace a REAL number specifying the calibration pace rate from 0 000018 to 0 0393336 seconds with a resolution of 600 nanoseconds number an INTEGER specifying the number of readings to be taken for this calibration This number must be from 1 to 32767 Discussion To use the calibration feature you must first short the Input and Input terminals of one of the channels on the card to card ground this gives a 0 volt input for that channel Then you specify that channel in the call to the Calibrate subroutine When the Calibrate call is executed the specified number of readings are taken at all gain settings and the average for each gain setting is saved The offsets are then used to calculate the proper correction values for positive and negative readings at each gain When subsequent readings are taken on other channels the correction value is subtracted from the reading prior to conversion to standard or user units No correction is applied to a reading expressed in base units Note that occasionally a Calibrate call will abort with an error 860 This may be caused by temporary transient electrical noise especially on calibration calls with small numbers of readings 860 errors from Calibrate calls should routinely be re tried several times and the connections of
58. e a pace interval longer than that allowed by the Measurement Library software 0 0393336 second you want the readings to be controlled by an external event rather than by time External pacing is primarily a hardware operation It is largely controlled by two hardware control lines IPACDA internal pace disable and EPCON external pace control There s not a lot of software involvement other than making the read requests that you would normally make for an internally paced read The timing of the execution of those read requests is controlled by the hardware There s no provision in the software for controlling IPACDA and EPCON directly you ll have to build your own circuits to control them In the next several paragraphs we will look at some of the features of the hardware and software that affect external pacing and then we will see how they fit together in external pacing applications In this manual we ll hmit our discussion of the hardware to telling you when the IPACDA and EPCON control lines must be set low or high we won t give you instructions for building the circuits that control those lines You can however get more information about those control lines from the ADC hardware manual part number 98640 90001 Hardware Considerations There are two control lines of interest for external pacing IPACDA determines whether the readings are paced by the internal pacing timer on the ADC card If IPACDA is low the internal p
59. e le returned for the reading is a If bit 12 1 the value returned for the reading is negative Update 1 November 1985 2 4 A ADC card calibration 1 7 configuration 1 5 1 8 2 3 configurations multiple 1 8 1 21 2 4 2 7 initialization 1 5 2 8 2 17 input pipeline 1 16 readings 1 9 sampling speed 1 1 1 20 Analog input pipeline 1 16 1 21 Array size limits 1 15 Base units 1 1 1 7 1 20 2 4 2 16 BASIC common area 1 5 error handling 1 8 extensions 1 2 heap area 1 5 interrupt mode 1 21 loading the Measurement Library subroutines 1 2 1 3 Measurement Library subroutine size 1 3 parameter typing 1 3 1 7 2 5 programming 1 2 1 3 1 5 C Calibrate subroutine 1 7 2 2 B 2 Calibration 1 1 1 5 1 7 2 2 Common area 1 5 Common mode overrange condition 1 7 1 8 1 17 1 19 1 20 2 4 Configuration of ADC cards 1 5 1 8 2 3 Config__0 subroutine 1 5 1 7 1 8 1 9 1 10 1 20 1 21 2 3 B 2 Control lines IPACDA and EPCON 1 23 CSUB package 1 1 Data conversion times 1 14 Disable__intr subroutine 1 21 2 6 B 2 Update 2 December 1987 INDEX 1 Index E Enable__intr subroutine 1 21 2 7 B 2 EPCON control line 1 23 Error handling 1 8 Error messages A 1 Error reporting 1 8 ERRN function 1 8 ESCAPECODE function 1 8 External pacing 1 23 G Gain 1 5 1 6 2 15 H Heap area 1 5 HP 14751A package 1 1 1 9 2 1 Init subroutine 1 5 1 21 2 8 2
60. e size of the data array data array in BASIC the name of a REAL array to hold the readings taken from the ADC card In Pascal this is a pointer to the real array that holds the readings rept an INTEGER giving the number of scans This number must be from 1 to 32767 the default value is 1 Discussion Sequential_ scan scans reads the channels on the ADC card sequentially from the start channel to the stop channel You can repeat the scans as many times as you want up to 32767 total scans The data array must be large enough to hold the total number of readings including repeats that you request One pace interval is used for all readings taken with the Sequential__scan routine This pace interval is valid only for the duration of the Sequential_ scan call after this call has completed the pace interval value reverts to the default value established with the Config__0 call The gain value used by Sequential_ scan is the default gain value set by the Config__0 or Set__gain call SET_ GAIN Set__gain sets the hardware gain used in taking readings from the ADC card Syntax BASIC Set_gain name gain Pascal PROCEDURE set_gain name str255 Parameters gain Discussion gain shortint a string or string literal specifying the ADC name assigned by the Config 0 call an INTEGER specifying the gain to be used in making readings The gain must have a value of 1 8 64 or 512 The gain set by the Set_ gain su
61. easurement Library features 1 1 general information 1 1 initialization 1 5 2 10 programming 1 2 quick reference B 1 size 1 3 1 4 software provided 1 2 subroutines 1 2 1 3 Meas_lib_ init subroutine 1 5 2 10 Messages A 1 Multiple configuration of an ADC card 1 8 1 20 Multiple configurations of an ADC card 2 4 2 7 INDEX 2 N Normal mode overrange condition 1 5 1 8 1 15 1 16 1 17 1 18 O ON ERROR mechanism 1 8 Overrange condition common mode 1 7 1 8 1 15 1 16 1 17 1 18 2 4 normal mode 1 5 1 8 1 15 1 16 1 17 1 18 P Pace interval 1 5 1 6 1 19 Pacing errors 1 19 Pacing external 1 21 Pascal common area 1 5 error handling 1 8 heap area 1 5 importing the Measurement Library 1 3 interrupt mode 1 4 1 19 2 7 Measurement Library size 1 4 parameter passing 1 4 parameter typing 1 4 1 7 2 1 2 5 programming 1 3 1 4 Pipeline 1 14 1 20 Programming general 1 2 1 4 in BASIC 1 2 1 3 1 4 in Pascal 1 3 1 4 Q Quick reference guide B 1 Random__scan subroutine 1 6 1 9 1 11 2 11 Read __channel subroutine 1 6 1 9 2 9 2 13 Reporting units 1 1 1 5 1 6 1 7 2 4 2 16 S Sampling speed 1 1 1 19 Sequential__scan subroutine 1 6 1 9 1 10 2 14 Setting error reporting parameter 1 5 gain 1 5 1 6 Index INDEX 3 Index pace interval 1 5 1 6 reporting units 1 5 1 6 Set__ gain subroutine 1 6 1 10 2 15 Set__units subroutine 1 6
62. econds per reading Applications External pacing applications divide into two general types single readings and bursts of readings Single readings The idea behind taking single externally paced readings is that you keep EPCON high until you want to take a reading set it low only long enough to take the reading and then set it high again The steps in taking a single reading are 1 Set IPACDA high IPACDA will remain high for the duration of externally paced readings 2 SetEPCON high This holds off all readings 3 Issue a call to Input read_ channel Sequential__scan or Random__scan 4 Wait The length of time you wait should be at least the set up time 5 When it is time to take a reading set EPCON low Keep it low for 1 to 15 microseconds then set it high again This will allow one and only one reading to be taken 6 Repeat step 5 until you have taken all the readings that you requested with the subroutine call in step 3 The subroutine will return to your application program only after all requested readings have been taken As indicated in step 4 each subroutine call you make requires that you wait the set up time before pulsing the EPCON line to take the first reading For Input or Read_ channel calls made in normal mode that means that you must wait the set up time before each reading If you re using Input in interrupt mode the set up time is required only before the first reading Keep in mind however that the EPC
63. ed W WAIT If bit 14 1 the ADC card was in the wait state at the time of the reading This means that the card was not read within the interval specified in the pacing timer that is a paced read was not made at the correct time You should never see this bit set since the ADC Library software reports an incorrectly paced read as an error and will not return a value for the reading O OVERRANGE If bit 13 0 a common mode overrange condition occurred during this reading and the reading is invalid Common mode overrange errors are discussed later in this section If bit 13 1 no common mode overrange condition occurred during this reading Note that the sense of this bit is negative true S SIGN If bit 12 0 the value returned for the reading is positive If bit 12 1 the value returned for the reading is negative l D DATA The data bits give the 12 bit binary magnitude of the voltage read from the ADC The sign of the voltage is given by the S bit bit 12 Note that all readings taken from the ADC card by the ADC Library software are returned to your program through real number parameters This includes readings in base units Thus while the base unit readings have integer values they look like real numbers to your program until you explicitly convert them to integers Assigning them to integer variables in BASIC or using the trunc or round function in Pascal will make the conversion 1 7 Using the Library
64. elow we will describe how to write your application program using the Measurement Library 5 Load the Measurement Library subroutines if they are not already part of the program you wrote in the previous step The subroutines are located on the Measurement Library disc Insert that disc into the master drive and issue the command LOADSUB ALL FROM MEAS _ LIB3 6 Run your program Debug as necessary repeating steps 4 through 6 General BASIC Programming The Measurement Library subroutines add approximately 23 700 bytes to your BASIC program The INTR2__1 binary adds approximately 1200 bytes Note that integer parameters used in the Measurement Library subroutine calls must be explicitly typed as INTEGER You can find out which parameters are integers by looking at the parameter descriptions in the subroutine call listings in Section 2 of this manual Real parameters and string parameters those ending in need not be explicitly typed Literal constants of any type integer real or string may be used Note that integers must not contain a decimal point You can invoke Measurement Library routines by calling them CALL statement or simply by entering them by name When you use them in an IF THEN statement or an ON statement the CALL must be explicit Using Pascal 2 0 2 1 or 3 0 You can call the Measurement Library subroutines from the Pascal language by importing the Measurement Library and using the library subroutin
65. ential scan Random_scan All except System_init and Config 0 All except Init System_init and Config 9 Config 0 Init Config 0 Input Random_scan Set gain and Config 0 Input Sequential scan Random_scan Calibrate and Config 0 Sequential scan Random scan and Calibrate Input Random_scan Sequential scan and Calibrate Random_scan Sequential scan Set_gain Set_units and Calibrate Input Sequential scan Random_scan and Calibrate Input Sequential scan Random_scan and Calibrate Input interrupt mode only Sequential scan Random_scan and Calibrate Set_units Config 0 Config 0 Calibrate BASIC Message Number 400 399 398 397 396 395 394 393 392 391 390 389 388 387 386 385 384 383 382 381 380 379 378 377 376 375 374 373 Pascal Message Number 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 Messages Pascal related Messages Meaning Normal termination Abnormal termination Not enough memory Reference to NIL pointer Integer overflow Divide by zero Real math overflow number too large Real math underflow number too small Value range error Case value range error Non zero I O result CPU word access to odd address CPU bus error Illegal CPU instruction CPU privilege violation Bad argument SIN COS Bad argument Natural Log Bad argument
66. entify the latest update if any already contained in your manual by referring to the printing history page Incorporate only the updates from this packet not already included in your manual Following the instructions on the back of this page replace existing pages with the update pages and insert new pages as indicated If any page is changed in two or more updates such as the printing history page which is furnished new for each update only the latest page will be included in the update package Destroy all replaced pages If write in instructions are included they are listed on the back of this page HEWLETT PACKARD COMPANY 98645 90001 Roseville Networks Division U0788 8000 Foothills Boulevard Update 3 Roseville California 95678 July 1988 U 1 TECHNICAL MANUAL UPDATE 98645 90001 Note that indicates a changed page UPDATE DESCRIPTION 3 Replace the following pages with the new pages attached Title ii All of Section 1 1 amp 2 Replace the following pages with the new pages attached itifiv 2 3 2 4 index 1 index 2 index 3 index 4 U 2 SECTION USING THE LIBRARY B INTRODUCTION The HP 98645A Measurement Library provides a set of easy to use subroutines for taking readings from the HP 98640A Analog to Digital Converter ADC card These subroutines can be used from the BASIC or Pascal language systems on HP 9000 Series 200 or Series 300 computers The subroutines are written in Pascal and
67. er for conversion to a numeric value The figures below show this circuit configured for a gain of 1 There are a couple of limitations that apply to this measurement circuit 1 The voltage output from an input op amp can not exceed 10 volts relative to system ground Fora gain of 1 this also means that the input voltage applied to the op amp can not exceed 10 volts again relative to system ground The situation gets rather more complicated for gains greater than one the formula for figuring the maximum input voltage is somewhat abstruse involving various voltages gains and a couple of 2s We won t get into the mathematics of it but figure 1 6 shows an example of the results that you may see Exceeding this input limit causes a common mode overrange the output of the op amp is clipped at its limit 10 volts or 10 volts and the overrange flag the O bit in a base unit reading is set to 1 2 The A to D converter which compares the outputs of the op amps can not measure a difference of more than 10 volts If the difference between those outputs is more than 10 volts the A to D converter clips its output value to 10 volts this situation is defined as a normal mode overrange The next few figures show various combinations of input voltages and the outputs they produce In the figures Input and Input voltages relative to system ground are shown in stick type like this 4 The differential input voltages are shown in R
68. es as procedure calls with the syntax described in Section 2 of this manual Typically you import the Measurement Library with a compiler directive of SEARCH MEAS LIB or SEARCH MEAS_L1IB3 and an import statement of 1 3 Using the Library IMPORT measurement_lib in your code Importing the Measurement Library adds about 17600 bytes to your Pascal program If the Pascal system modules INTERFACE and IO have not been merged into the system library file you will also have to include the compiler directive SEARCH INTERFACE IO Note that the after each file name is significant The procedure calls for the Measurement Library are all exported from the file MEAS_ LIB CODE or MEAS__LIB3 CODE along with the following types TYPE shortint 32768 32767 byte 0 255 str255 string 255 iarraytype ARRAY O maxint OF shortint rarraytype ARRAY O maxint OF real rarraypt rarraytype iarraypt iarraytype Due to the rigorous structure of the Pascal language you can t default parameters in the procedure calls However to save you the bother of declaring real and integer arrays for the pace and gain array parameters of the random_ scan procedure you can use the default pace or gain value established by a call to Config __0 or Set_ gain by specifying a O for the array size and a NIL for the array pointer All other parameters for all procedure calls must be explicitly provided in
69. fined This is because the Sequential_ scan subroutine uses the array space as temporary storage for a variety of nasty messy variables it doesn t fill the array with nice clean data until just before it returns to your program If the subroutine aborts while the array space is filled with garbage and your program tries to interpret the garbage as data you may not be pleased with the results The pace interval that you specify when you call Sequential_ scan will be maintained only for the duration of that call After the readings have been taken the pace interval will revert to its previous value Random scan Use Random _scan when you need lots of flexibility Random__scan lets you read from the channels on a card in any order and you can assign an individual pace interval and gain for each reading Additionally you can repeat the set of readings as many times as you want The readings are controlled by a set of arrays A channel array lists the order of the channels to be read A gain array lists the gains for the readings A pace array lists the pace intervals that will elapse between readings And a data array stores the results The sizes of the channel pace and gain arrays need not be the same The Random __scan subroutine simply starts at the beginning of each array and uses the values in sequence After Random_ scan uses the last element in an array it goes back to the beginning of the array for the next value Note that the gain
70. fset ir your readings or both For example say you were taking readings from a 4 to 20 mA current loop transmitter connected to a flow meter Say further that the range of the flow meter was from 0 to 50 gallons per minute and that you were making your voltage readings across a 250 ohm resistor That would mean that a reading of 1 0 volts corresponded to a flow rate of 0 gpm and that 5 0 volts corresponded to 50 gpm Using y mx b you can derive a multiplier of 12 5 and an offset of 12 5 and specify these as parameters to a Config__0 call 180 Config 0 Flow 98640A 18 1 01 No User 12 5 12 5 Then whenever you take a reading from that current loop the result is expressed directly in gallons per minute That s a lot easier than making a conversion from standard units every time you take a voltage reading Error Reporting and Handling The Measurement Library reports errors for a variety of reasons Typical errors include configuration errors pacing errors and overrange errors When such an error occurs the Measurement Library forces a system error and returns the error number Your application program can trap and handle these errors using the ON ERROR mechanism in BASIC or the Try Recover mechanism in Pascal In BASIC you can get the error number with the ERRN function in Pascal use the ESCAPECODE function Certain run time errors may be reported in BASIC as the Pascal error number plus 400 These errors are listed in A
71. ged or linked to the Measurement Library using the Pascal system librarian program Be sure to transfer ALL the modules in MEAS __LIB or MEAS_LIB3 If IO is not in your system library file you will also have to transfer the module IOCOMASM from the file IO found on your LIB disc Interrupt mode operation is not supported in the Pascal environment That means we don t guarantee that it will work If you try it and it doesn t work you can purchase consulting services from the nearest HP sales and service office See the back section of this manual for a list of sales and service offices An interrupt service routine ISR is required for interrupt mode to work in Pascal and we do not provide a Pascal ISR with the Measurement Library If you try to use interrupt mode in Pascal without a proper ISR you will probably crash your system If you re an experienced Pascal programmer you may be able to Update 3 July 1988 1 4 Using the Library write your own ISR For more information on ISRs refer to the Pascal 2 0 System Designer s Guide part number 09826 90074 WRITING THE PROGRAM In both BASIC and Pascal writing your application program involves two major activities setting up the card to take readings and taking the readings In addition BASIC programs may take readings in interrupt mode We will cover these subjects in the paragraphs that follow We will also say a few words about externally paced readings All of the subrou
72. he HP 98645A Measurement Library includes these subroutine packages MEAS _LIB for use with BASIC 2 0 MEAS _LIB3 for use with BASIC 3 0 MEAS _LIB for use with BASIC 4 0 MEAS _ LIBS for use with BASIC 5 0 MEASLIB42 for use with BASIC 4 0 on a Model 320 computer MEASLIB 52 for use with BASIC 5 0 or 5 1 on a Model 320 computer INTR2__1 for use with interrupt mode in BASIC 2 1 MEAS __LIB CODE for use with Pascal 2 0 2 1 MEAS _LIB3 CODE for use with Pascal 3 0 3 1 3 2 MEASLIB32 CODE for use with Pascal 3 1 3 2 on a Model 320 computer The software is provided on the following media Option 630 3 1 2 floppy disc Option 655 5 1 4 floppy disc MEAS _LIB and MEAS__LIB CODE will not use floating point hardware MEAS _LIB3 MEAS_ LIB4 MEAS __LIBS and MEAS _LIB3 CODE will use a Floating Point Math card if it is installed in the system otherwise they will use the Pascal floating point library routines MEASLIB42 MEASLIBS2 and MEASLIB32 CODE will use the built in floating point hardware in the Model 320 computer these routines are not compatible with any other processor THE GENERAL APPROACH The way you write programs using the Measurement Library is pretty much the same whether you use the BASIC or Pascal language system There are however significant differences in the way you set up you system environment We will discuss these differences in the next few paragraphs Using BASIC 2 1 If you are using the BASIC 2 1 system take the f
73. incurs the extra time required for two readings it is difficult if not impossible to maintain accurate and even pacing of readings between one subroutine call and the next If your application requires accurate pacing for a block of readings we suggest that you make all of those readings with one subroutine call Use Sequential_scan or Random _ scan as appropriate to your application For readings taken in interrupt mode the Measurement Library software does not take care of the pipeline for you You must keep track of which readings are which not a very taxing operation and throw out the garbage More information on interrupt mode programming is contained later in this section Overrange Errors You can encounter two kinds of overrange conditions with the ADC card normal mode overrange and common mode overrange Normal mode overrange occurs when the input voltage exceeds the range of the analog to digital converter Common mode overrange occurs when either side of the differential input voltage exceeds the maximum input voltage of its input amplifier The next several paragraphs explain how these overrange conditions can affect your readings Using the Library The voltage measured by the ADC card is the differential input voltage between the Input and Input terminals of a channel on the card The two sides of the input signal pass through separate input amplifiers op amps and are then sent to an analog to digital A to D convert
74. ious values The operation of the Input subroutine in interrupt mode is different from its normal operation Refer to the discussion of interrupt mode later in this section for more details Sequential scan Use the Sequential_ scan subroutine to fake readings on all channels in sequence from a starting channel to an ending channel These readings are all taken at the same pace rate which you specify and the same gain specified by the most recent call to Config__0 or Set__gain and the values are returned to a data array Optionally you can repeat the readings as many times as you want For example if you wanted to take readings from channels 2 through 7 on an ADC card at the same gain and pace rate Sequential__scan would be the appropriate subroutine to use In BASIC 100 INTEGER Start Stop Repeat 110 REAL Data 1 6 230 Name A0C 240 Start 2 250 Stop 7 260 Pace 0 01 270 Rept 1 460 Sequential _scan Name Start Stop Pace Data Rept In Pascal CONST name ADC pace 0 01 start 2 stop 7 rept 1 d_ size 6 TYPE d_array ARRAY 1 6 OF real d_ ptr d array VAR data d_ ptr new data sequential_scan name start stop pace d_size data rept E Using the Library You must make sure that your data array is large enough to hold all of the readings that the Sequential__scan call will generate Note that if the call to Sequential__scan aborts the contents of the array will be unde
75. ish This would allow you to take readings from different voltage sources on different channels of the same card without reconfiguring the card all the time For example say you had flow meters connected to channels 1 2 and 3 of the card and thermocouples connected to channels 4 5 6 and 7 You could specify one name for a flow meter configuration and another name for a thermocouple configuration 1 8 Using the Library 180 Config 0 Flow gt 98640A 18 1 01 No User 12 5 12 5 190 Config 0 Thermo 98640A 18 64 01 No Standard e When you want to take a reading from either type of voltage source just specify the name of the appropriate configuration in your reading call 420 Input Thermo 5 Tvolt 430 Input Flow 2 Gpm If 16 different ADC configurations are not enough for your application you can get more by re using existing names Do this by making a call to Config 0 and specifying an existing name the old configuration parameters for that name will be erased and the new parameters or their default values will replace them You will then have to re initialize the name with a call to the Init subroutine before you can use the new configuration Note that the use of different names for the same ADC card will not work in interrupt mode DO NOT ATTEMPT TO ACCESS AN ADC BY A DIFFERENT NAME DURING INTERRUPT MODE DATA TRANSFERS Taking Readings Taking readings is the whole reason for having an ADC car
76. llowing array elements Channel chan_array i mod size of chan_array Pace pace array i mod size _of pace array Gain gain array i mod size of gain array Data datali Make sure that the data array is large enough to hold all of the readings that will be generated by the Random__scan call Don t forget to account for repeats As with Sequential_scan if the call to Random_ scan aborts the contents of the array will be undefined The channel pace and gain arrays must be dimensioned as arrays even if they are only single valued Scalar variables can not be used The pace and gain values specified in Random_scan are used only for the duration of the Random__scan call After the readings have been taken pace and gain revert to their previous values Special Considerations in Taking Readings Timing of readings Even though the Measireiient Library can take readings at the full 55 kHz sampling speed of the ADC card it can t return the results to your program that fast The reason for this is the system overhead of BASIC or Pascal and the overhead of the Measurement Library itself For any given set of readings the Measurement Library goes through the following steps a Set up the card b Take the reading s at the specified pace rate c Convert the readings to the requested data format This includes checking the WAIT bit to make sure there wasn t a pacing error The values below indicate the time required to pro
77. ly HEWLETT PACKARD HP 98645A Measurement Library User s Library HP 98645A Measurement Library User s Manual DA Packar Update 3 July 1988 HEWLETT PACKARD COMPANY Manual Part Number 98645 90001 Roseville Networks Division E0684 8000 Foothills Boulevard Printed in U S A Roseville California 95678 June 1984 PRINTING HISTORY The Printing History below identifies the Edition of this Manual and any Updates that are included Periodically update packages are distributed which contain replacement pages to be merged into the manual including an updated copy of this Printing History page Also the update may contain write in instructions Each reprinting of this manual will incorporate all past updates however no new information will be added Thus the reprinted copy will be identical in content to prior printings of the same edition with the user inserted update information New editions of this manual will contain new information as well as updates 98645 90001 First Edition June 1984 Update A ce ee November 1985 Update Bici as a ESS December 1987 Upd te AA A eR July 1988 NOTICE The information contained in this document is subject to change without notice HEWLETT PACKARD MAKES NO WARRANTY OF ANY KIND WITH REGARD TO THIS MATERIAL INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE Hewlett Packard shall no
78. n tine gt lt gt Figure 1 1 Analog input operation Using the Library However to maximize throughput the ADC card pipelines the readings That is while the value for one reading is being returned the voltage for the next reading is being latched and converted and the channel address is being provided for the reading after that For example during time period t3 in the figure below the first reading is taken from the card while the second reading is being converted and the third address is being supplied honor es address 1 convert 1 Figure 1 2 Analog Input Pipeline To start the flow of readings the Measurement Library software primes the pipeline by taking two garbage readings at times t1 and t2 in the figure above these two readings are thrown away Their only purpose was to start pulling valid readings through the pipeline The third reading taken is the first valid reading since it is the first reading that has gone through all three stages of the pipeline it is written into the data array as the first reading For all readings taken in normal mode the Measurement Library software takes care of priming and emptying the pipeline it does this by taking two more readings than are requested and throwing away the two extra garbage values This happens for each subroutine call you never have to pay any attention to it since the software takes care of it all Note that since each subroutine call
79. n any of the other channels the appropriate correction value is subtracted from the raw reading before conversion to standard or user units Reporting Units Reporting units come in three flavors base standard and user you specify one of these with the Config Oor Set__units command The units are Base units Base units are in the form of a 16 bit binary integer of which twelve bits represent the magnitude of the reading Readings reported in base units are raw readings gain factors and calibration corrections are not applied to base units The format of a base unit reading is 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 P eet Stee a ee ee ee ee ee ee ees IBiwlo jJs JoITODIDIDIDI DIDI DIDI DI oI oD She ha nn nn han hn hn pn han thn npn S where B BUSY If bit 15 1 the ADC is busy The reading is not taken and all other bits are invalid If bit 15 0 a valid reading is returned W WAIT If bit 14 1 the ADC card was in the wait state at the time of the reading This means that the card was not read within the interval specified in the pacing timer that is a paced read was not made at the correct time Generally you will not see this bit set since the ADC Library software reports an incorrectly paced read as an error and will not return a value for the reading O OVERRANGE If bit 13 0 a common mode overrange condition occurred during this reading and the reading is invalid Common mode overrange errors are discussed
80. n ouw t NO oD WM we we we we we new pace pace 1 0 02 new gain gain 1 gain 2 gain 3 new data random_scan name c_size channel d_size data rept p_size pace g_size gain Using the Library 1 13 Using the Library In the general case the ith reading is taken using the following array elements Channel chan_array i mod size of chan array Pace pace_array i mod size of pace array Gain gain array i mod size _of gain array Data data i Make sure that the data array is large enough to hold all of the readings that will be generated by the Random__scan call Don t forget to account for repeats As with Sequential scan if the call to Random_ scan aborts the contents of the array will be undefined The channel pace and gain arrays must be dimensioned as arrays even if they are only single valued Scalar variables can not be used The pace and gain values specified in Random_scan are used only for the duration of the Random__scan call After the readings have been taken pace and gain revert to their previous values The Pipeline The ADC requires three operations to produce a reading 1 provide the channel address for the reading 2 latch the voltage and convert it to a digital value 3 return the value to the host computer For any given reading these three operations must be done serially hon horno Hon address convert return E da honran ho
81. n this manual we ll limit our discussion of the hardware to teliing you when the IPACDA and EPCON control lines must be set low or high we won t give you instructions for building the circuits that control those lines You can however get more information about those control lines from the ADC hardware manual part number 98640 90001 Hardware Considerations There are two control lines of interest for external pacing IPACDA determines whether the readings are paced by the internal pacing timer on the ADC card If IPACDA is low the internal pacing timer of the card is used if IPACDA is high the internal pacing timer is bypassed and readings are taken at the free run speed of the card one reading every 18 microseconds Note that IPACDA must be high when readings start in order for the timing of the first reading of a series to be accurately known IPACDA can be set low after the start of readings if you want the readings to be paced by the internal pacing timer EPCON controls whether or not any readings are taken If EPCON is low readings are taken whenever they are requested If EPCON is high requested readings are held off a read request will not complete until EPCON goes low again In summary when EPCON is low readings are taken at the free run speed of the card if IPACDA is high or at the time programmed into the internal pacing timer if IPACDA is low When EPCON is high readings stop Software Considerations When making
82. ntical to an already used name all configuration parameters for the old name will be erased and the new configuration parameters or defaults will be used The name will then have to be reinitialized with Init before it is accessed All readings taken by the ADC are reported in one of three reporting units base standard or user Base units are in the form of a 16 bit binary integer with the following format 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Hm ah an pn hn nn pnw eh meh we pan ohn nth ne pan npn npn nn tenn gan nt ejwJojsjpojo ojpbjbjojpb bjbjoJjoDJ D m ae hn wpe pn npn neha wh han npn een we pen ste Et tenn a MSB LSB where B BUSY If bit 15 1 the ADC is busy The reading is not taken and all other bits are invalid If bit 15 0 a valid reading is returned W WAIT If bit 14 1 the ADC card was in the wait state at the time of the reading This means that the card was not read within the interval specified in the pacing timer that is a paced read was not made at the correct time Generally you will not see this bit set since the ADC Library software reports an incorrectly paced read as an error and will not return a value for the reading O OVERRANGE If bit 13 0 a common mode overrange condition occurred during this reading and the reading is invalid If bit 13 1 no common mode overrange condition occurred during this reading Note that the sense of this bit is negative true S SIGN If bit 12 0 th
83. nventions apply The parameters list for the subroutine appears in parentheses These parentheses must be included in the subroutine call Optional parameters BASIC only are contained within square brackets String parameters for name and model number are case sensitive That is don t use lower case characters in place of upper case and vice versa All other string parameters are case insensitive Note that none of the parameters in Pascal calls are optional Pascal data types exported by the Measurement Library are as follows TYPE shortint 32768 32767 byte 0 255 str255 string 255 iarraytype ARRAY O maxint OF shortint rarraytype ARRAY O maxint OF real rarraypt rarraytype iarraypt iarraytype The remainder of this section gives the subroutine call syntax arranged by subroutine in alphabetical order Note that parameters identified as INTEGER are of type INTEGER in BASIC but of type shortint in Pascal 2 1 CALIBRATE Calibrate allows you to measure and compensate for the various offsets in the ADC card To do this Calibrate dedicates one channel on the card to making reference readings the offsets derived from the reference readings are used to adjust the readings taken on the remaining channels of the card Syntax BASIC Calibrate name channel pace number Pascal PROCEDURE calibrate name str255 channel shortint pace real number shortint Parameters nam
84. of any other Measurement Library calls in interrupt mode will result in an error When you are in interrupt mode the Measurement Library does not automatically take care of setting up and clearing out the input pipeline Refer to the description of the analog input pipeline earlier in this section Thus when you take a reading with the Input subroutine the result you get is the value of the reading taken two readings ago You should discard the data returned from the first two Input calls Interrupt mode does not handle multiple configurations of the same card cleanly To avoid taking erroneous readings do not take readings from different configurations names for the same card while in interrupt mode The shortest recommended pacing interval in interrupt mode is 36 milliseconds This is very close to the longest pacing interval available from the ADC card 39 3336 milliseconds You can get longer pacing intervals by using external pacing External pacing is discussed later in this section The following example shows a BASIC program that takes readings in interrupt mode Its purpose is to take 3 voltage readings to do that it takes 10 readings and ignores the first 2 invalid readings 40 REAL Volts 1 8 50 I 2 110 Config 0 ADC 98640A 18 1 036 120 Init ADC 130 Enable _intr ADC 140 ON INTR 18 GOSUB Service 150 Input ADC 5 Volts 1 340 Service t 350 Input ADC 5 Volts 1 2 360 I I 1 370 IF I gt 10
85. ollowing steps to get your application up and running 1 Boot up BASIC 2 0 2 Load the BASIC 2 1 extensions The 2 1 extensions are located on the Extended BASIC 2 1 disc Insert that disc into the master drive and issue the command LOAD BIN AP2__1 3 Load the interrupt processing package if you will be taking readings in interrupt mode Interrup mode readings are discussed later in this section The interrupt processing package is located on thi Measurement Library disc Insert that disc into the master drive and issue the command LOAI BIN INTR2_ 1 4 Load any other BASIC extensions that you need for your application For example this would b the time to load Graphics 2 1 5 Write your BASIC program or load a previously written program into memory In the paragraph below we will describe how to write your application program using the Measurement Library Update 3 July 1988 1 2 Using the Library 6 Load the Measurement Library subroutines if they are not already part of the program you wrote in the pr vious step The subroutines are located on the Measurement Library disc Insert that disc into the master drive and issue the command LOADSUB ALL FROM MEAS _ LIB 7 Run your program Debug as necessary repeating steps 5 through 7 Using BASIC 3 0 4 0 5 0 or 5 1 If you are using the BASIC 3 0 BASIC 4 0 BASIC 5 0 or BASIC 5 1 system take the following steps to get your application up and running 1 Boot
86. oman type like this 6 Figure 1 3 shows a typical reading that causes no problems The input voltages propagate through the op amps with no clipping the differential voltage is well within the range of the A to D converter and the converter comes up with the correct value 4 6 6 A to D Converter 2 Figure 1 3 Reading OK Using the Library Figure 1 4 shows a normal mode overrange condition The Input and Input voltages are within the range of their respective op amps but the differential input voltage 12 volts is too great for the A to D converter The result is a normal mode overrange condition yielding a full scale and incorrect reading from the A to D converter 12 10 A to D Converter Figure 1 4 Normal mode overrange Figure 1 5 shows a common mode overrange condition The Input voltage of 12 volts is clipped to 10 volts and the overrange flag O bit is set to 1 The differential voltage presented to the A to D converter is within the range of the converter so it converts the voltage correctly and comes up with the wrong answer 2 A to D Converter Figure 1 5 Common mode overrange Using the Library Figure 1 6 shows a subtler form of common mode overrange that you may encounter at gains greater than 1 This is because the programmable gain amplifier amplifies the difference between the Input and Input voltages before sending the result to the A to
87. on the Measurement Library disc Insert that disc into the master drive and issue the command LOAD BIN INTR2_ 1 4 Load any other BASIC extensions that you need for your application For example this would be the time to load Graphics 2 1 5 Write your BASIC program or load a previously written program into memory In the paragraphs below we will describe how to write your application program using the Measurement Library 6 Load the Measurement Library subroutines if they are not already part of the program you wrote in the previous step The subroutines are located on the Measurement Library disc Insert that disc into the master drive and issue the command LOADSUB ALL FROM MEAS _ LIB 7 Run your program Debug as necessary repeating steps 5 through 7 1 2 Using the Library Using BASIC 3 0 If you are using the BASIC 3 0 system take the following steps to get your application up and running 1 Boot up BASIC 3 0 2 Load the BASIC 3 0 IO binary if you will be taking readings in interrupt mode Interrupt mode readings are discussed later in this section The IO binary is located on the BASIC 3 0 Language Binary disc Insert that disc into the master drive and issue the command LOAD BIN IO 3 Load any other BASIC binaries that you need for your apphca tion For example this would be the time to load graphics routines 4 Write your BASIC program or load a previously written program into memory In the paragraphs b
88. pecify the select code of the card its gain a pace rate for taking readings an error reporting parameter for normal mode overrange errors and the units base standard or user in which the readings will be reported Reporting units are discussed below If you do not supply these optional parameters Config__0 will supply default values Init resets an individual card disables interrupts for that card and sets the calibration array for that card to its default values Init must be used before any other calls except Meas_lib_ init Config__0 and System_ init System init is the same as Init except that it initializes all cards that have been configured Update 3 July 1988 1 5 Using the Library The set up portion of a typical BASIC program might look like this 20 COM Heapcom INTEGER Heaparea 1 1300 30 INTEGER Select code Gain 40 Name ADC 50 Model 98640A 60 Select_code 18 70 Gain 1 80 Pace 0 01 90 Error No 100 Unit Standard 220 Meas_lib init 230 Config O Name Model Select_code Gain Pace Error Unit 240 Init Name The analogous Pascal code would look like this CONST name ADC model 98640A select code 18 gain 1 pace 0 01 error NO units STANDARD multiplier 1 0 offset 0 0 BEGIN meas lib init config O name model select_code gain pace error units multiplier offset init name The most frequently used configuration parameters can
89. plifies the difference between the Input and Input voltages before sending the result to the A to D converter Even though the input voltages appear to be acceptable the amplifier may try to boost them out of the acceptable range In this case the programmable gain circuit tries to boost the Input voltage to 11 5 volts but the output limit of the op amp keeps the voltage from exceeding 10 volts The overrange flag O bit is set to one and the clipped voltage is sent to the A to D converter The resulting value is incorrect 8 1 6 5 A to D Converter 7 Figure 1 6 Common mode overrange at gain greater than 1 A normal mode overrange is indicated when a reading returns the maximum possible magnitude value This is the same as clipping The maximum magnitude value depends on the units in use as follows Base 4095 all D bits set to 1 Standard 4095 isb calibrate gain User 4095 isb calibrate gain multiplier offset where Isb 10 4095 volts bit Update 3 July 1988 1 19 Using the Library Note that it is not possible to tell the difference between a full scale reading and a normal mode overrange reading By default a normal mode overrange condition does not generate an error However by setting a parameter in the Config__0 call you can cause an error to be generated when a normal mode overrange occurs Common mode overranges are harder to detect than normal mode overranges sin
90. ppendix A If the errors are not trapped your program will abort and the system will report the error The errors that can be returned by the Measurement Library are listed in Appendix A Note that one of the parameters of the Config __0 subroutine determines whether normal overranges are reported as errors or not Note also that if you are using base units no overrange errors either normal or common mode are reported You can detect overrange conditions from the bits returned in base unit format Overrange errors and pacing errors are discussed in more detail later in this chapter Multiple Configurations The Measurement Library allows you to have up to 16 different ADC card configurations at any one time Each configuration requires a separate call to Config__0 and each call specifies a unique name for a card You can assign multiple names and thus multiple configurations to a single card if you wish This would allow you to take readings from different voltage sources on different channels of the same card without reconfiguring the card all the time For example say you had flow meters connected to channels 1 2 and 3 of the card and thermocouples connected to channels 4 5 6 and 7 You could specify one name for a flow meter configuration and another name for a thermocouple configuration Update 3 July 1988 1 8 Using the Library 180 Config 0 Flow 98640A 18 1 01 No User 12 5 12 5 190 Config 0 Thermo
91. r parameters used in the Measurement Library subroutine calls must be explicitly typed as INTEGER You can find out which parameters are integers by looking at the parameter descriptions in the subroutine call listings in Section 2 of this manual Real parameters and string parameters those ending in need not be explicitly typed Literal constants of any type integer real or string may be used Note that integers must not contain a decimal point You can invoke Measurement Library routines by calling them CALL statement or simply by entering them by name When you use them in an IF THEN statement or an ON statement the CALL must be explicit Update 3 July 1988 1 3 Using the Library Using Pascal 2 0 2 1 3 0 3 1 or 3 2 You can call the Measurement Library subroutines from the Pascal language by importing the Measurement Library and using the library subroutines as procedure calls with the syntax described in Section 2 of this manual Typically you import the Measurement Library with a compiler directive of SEARCH MEAS LIB or SEARCH MEAS_LIB3 or SEARCH MEASLIB32 and an import statement of IMPORT measurement_lib in your code Importing the Measurement Library adds about 17600 bytes to your Pascal program If the Pascal system modules INTERFACE and IO have not been merged into the system library file you will also have to include the compiler directive SEARCH INTERFACE I0
92. reasons Typical errors include configuration errors pacing errors and overrange errors When such an error occurs the Measurement Library forces a system error and returns the error number Your application program can trap and handle these errors using the ON ERROR mechanism in BASIC or the Try Recover mechanism in Pascal In BASIC you can get the error number with the ERRN function in Pascal use the ESCAPECODE function Certain run time errors may be reported in BASIC as the Pascal error number plus 400 These errors are listed in Appendix A If the errors are not trapped your program will abort and the system will report the error The errors that can be returned by the Measurement Library are listed in Appendix A Note that one of the parameters of the Config 0 subroutine determines whether normal overranges are reported as errors or not Note also that if you are using base units no overrange errors either normal or common mode are reported You can detect overrange conditions from the bits returned in base unit format Overrange errors and pacing errors are discussed in more detail later in this chapter Multiple Configurations The Measurement Library allows you to have up to 16 different ADC card configurations at any one time Each configuration requires a separate call to Config__ 0 and each call specifies a unique name for a card You can assign multiple names and thus multiple configurations to a single card if you w
93. s This puts an upper limit on the signal frequency component that the ADC can measure accurately at the 18 microsecond sample rate The following table shows that maximum frequency component for each gain for readings to within 1 lsb on a single channel Maximum Signal Gain Frequency Component 1 27 kHz 8 27 kHz 64 15 kHz 512 3 5 kHz When more than one channel is being sampled as in Sequential_ scan and Random _ scan operations the speed of accurate sampling by the ADC is limited as follows Minimum Pace Time for Equivalent Max imum Gain Multichannel Scans Sampling Speed 1 50 microseconds 20000 readings per second 8 50 microseconds 20000 readings per second 64 71 microseconds 14000 readings per second 512 1000 microseconds 1000 readings per second Interrupt Mode Interrupt mode operation is supported only in the BASIC language system It is NOT supported in Pascal Interrupt mode is useful when you want your program to continue execution between readings and still maintain an accurate or externally controlled pace rate There are two subroutines associated specifically with interrupt mode Enable__intr and Disable intr Appropriately enough interrupt mode is enabled by a call to Enable __intr and is disabled by a call to Disable __intr Using the Library Only a limited subset of Measurement Library subroutine calls are allowed after you have entered interrupt mode Input Config 0 Init System_ init Disable __intr Use
94. scan subroutine 1 6 1 9 1 11 2 11 B 2 Readings timing of 1 14 Read__channel subroutine 1 6 1 9 2 9 2 13 B 2 Reporting units 1 1 1 5 1 6 1 7 2 4 2 16 Index Update 2 December 1987 INDEX 3 Index S Sampling speed 1 1 1 20 Sequential_ scan subroutine 1 6 1 9 1 10 2 14 B 2 Set up times 1 14 Setting error reporting parameter 1 5 gain 1 S 1 6 pace interval 1 5 1 6 reporting units 1 5 1 6 Set__gain subroutine 1 6 1 10 2 15 B 2 Set__units subroutine 1 6 1 7 1 8 2 16 B 2 Standard units 1 1 1 7 1 8 1 20 2 5 2 16 Subroutine calls Calibrate 1 7 2 2 B 2 Config__0 1 5 1 7 1 8 1 9 1 10 1 20 1 21 2 3 B 2 Disable_ intr 1 21 2 6 B 2 Enable __intr 1 21 2 7 B 2 Init 1 5 1 21 2 8 2 17 B 2 Input 1 6 1 9 1 21 2 7 2 9 B 2 Meas_lib_ init 1 5 2 10 B 2 Random__scan 1 6 1 9 1 11 2 11 B 2 Read _ channel 1 6 1 9 2 9 2 13 B 2 Sequential scan 1 6 1 9 1 10 2 14 B 2 Set_ gain 1 6 1 10 2 15 B 2 Set_ units 1 6 1 7 1 8 2 16 B 2 System__init 1 5 1 21 2 17 B 2 System __ init subroutine 1 5 1 21 2 17 B 2 Timing of readings 1 14 Try Recover mechanism 1 8 U Units 1 1 1 5 1 6 1 7 2 4 2 16 User units 1 1 1 7 1 8 1 20 2 5 2 16 Update 1 November 1985 INDEX 4 HP Computer Systems HP 98645A Measurement Library User s Manual a ais pee we iF ae g i LA Packar Q HEWLETT PACKARD Warranty Statement
95. specify when you call Sequential__ scan will be maintained only for the duration of that call After the readings have been taken the pace interval will revert to its previous value l Random _scan Use Random__ scan when you need lots of flexibility Random__scan lets you read from the channels on a card in any order and you can assign an individual pace interval and gain for each reading Additionally you can repeat the set of readings as many times as you want The readings are controlled by a set of arrays A channel array lists the order of the channels to be read A gain array lists the gains for the readings A pace array lists the pace intervals that will elapse between readings And a data array stores the results The sizes of the channel pace and gain arrays need not be the same The Random__scan subroutine simply starts at the beginning of each array and uses the values in sequence After Random_ scan uses the last element in an array it goes back to the beginning of the array for the next value Note that the gain and pace values do not start over just because the channel array repeats For example consider an ADC card that has flowmeters attached to channels 2 3 4 and 5 and thermocouples attached to channels 6 and 7 Say that you wanted to take the following sets of readings Channel 2 3 6 4 5 7 Pace 02 02 02 02 02 02 Gain 1 1 64 1 1 64 To take these readings you could set up the following arrays Channel 2
96. stick type like this 4 The differential input voltages are shown in Roman type like this 6 Update 3 July 1988 1 17 Using the Library Figure 1 3 shows a typical reading that causes no problems The input voltages propagate through the op amps with no clipping the differential voltage is well within the range of the A to D converter and the converter comes up with the correct value A to D Figure 1 3 Reading OK Figure 1 4 shows a normal mode overrange condition The Input and Input voltages are within the range of their respective op amps but the differential input voltage 12 volts is too great for the A to D converter The result is a normal mode overrange condition yielding a full scale and incorrect reading from the A to D converter 12 10 A to D Converter Figure 1 4 Normal mode overrange Update 3 July 1988 1 18 Using the Library Figure 1 5 shows a common mode overrange condition The Input voltage of 12 volts is clipped to 10 volts and the overrange flag O bit is set to 1 The differential voltage presented to the A to D converter is within the range of the converter so it converts the voltage correctly and comes up with the wrong answer 2 A to D Converter Figure 1 5 Common mode overrange Figure 1 6 shows a subtler form of common mode overrange that you may encounter at gains greater than 1 This is because the programmable gain amplifier am
97. stment to all readings Re set gain or units at any time Take readings at the full 55 kHz sampling speed of the ADC card from either BASIC or Pascal Take readings under interrupt mode in BASIC 1 1 Using the Library Software Provided The HP 98645A Measurement Library includes these subroutine packages MEAS _ LIB for use with BASIC 2 0 MEAS __LIB3 for use with BASIC 3 0 INTR2_ 1 for use with interrupt mode in BASIC 2 1 MEAS _LIB CODE for use with Pascal 2 0 2 1 MEAS _LIB3 CODE for use with Pascal 3 0 The software is provided on the following media Option 630 3 1 2 floppy disc Option 655 5 1 4 floppy disc THE GENERAL APPROACH The way you write programs using the Measurement Library is pretty much the same whether you use the BASIC or Pascal language system There are however significant differences in the way you set up your system environment We will discuss these differences in the next few paragraphs Using BASIC 2 1 If you are using the BASIC 2 1 system take the following steps to get your application up and running 1 Boot up BASIC 2 0 2 Load the BASIC 2 1 extensions The 2 1 extensions are located on the Extended BASIC 2 1 disc Insert that disc into the master drive and issue the command LOAD BIN AP2_ 1 3 Load the interrupt processing package if you will be taking readings in interrupt mode Interrupt mode readings are discussed later in this section The interrupt processing package is located
98. t be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing performance or use of this material This document contains proprietary information which is protected by copyright All rights are reserved No part of this document may be photocopied reproduced or translated to another language without the prior written consent of Hewlett Packard Company Copyright O 1984 1985 1987 1988 by HEWLETT PACKARD COMPANY Update 3 July 1988 ii MANUAL UPDATE MANUAL IDENTIFICATION UPDATE IDENTIFICATION Title HP 98645A Measurement ee Update Number 3 July 1988 User s Manual This update also includes Part Number 98645 90001 Update 2 December 1987 Update 1 November 1985 This Update Goes With First Edition June 1984 THE PURPOSE OF THIS MANUAL UPDATE is to provide new information for your manual to bring it up to date This is important because it ensures that your manual accurately documents the current version of the product THIS UPDATE CONSISTS OF this cover sheet a printing history page if any any replacement pages and write in instructions if any Replacement pages are identified by the update number at the bottom of the page A vertical line change bar in the outside margin indicates new or changed text material The change bar is not used for typographical or editorial changes that do not affect the content of the text TO UPDATE YOUR MANUAL id
99. terrupt level possible in this case 6 See the 98640A Reference Manual HP part number 98640 90001 for details When using the interrupt mode it is important to determine experimentally that the pace interval being used is compatible with the BASIC program instructions being executed while waiting for interrupts on the particular computer family on which the program is executing The following example shows a BASIC program that takes readings in interrupt mode Its purpose is to take 8 voltage readings to do that it takes 10 readings and ignores the first 2 invalid readings 40 50 110 120 130 140 150 340 350 360 370 380 390 400 410 420 430 440 450 460 REAL Volts 1 8 I 2 Config 0 ADC 98640A 18 1 036 Init ADC Enable _intr ADC ON INTR 18 GOSUB Service Input ADC 5 Volts 1 Service t Input ADC 5 Volts 1 2 I I 1 IF I gt 10 THEN OFF INTR 18 Disable intr ADC FOR J 1 TO 8 PRINT Volts J NEXT J STOP END IF RETURN END Update 3 July 1988 1 22 Using the Library Note that the order of the Enable_ intr call and the ON INTR statement is not critical Enable_ intr does not physically enable interrupts on the ADC card it only sets flags in the Measurement Library The card interrupts are physically enabled by the first Input call after Enable__intr line 150 in this example External Pacing You might use external pacing for ADC readings if you want to us
100. that the interrupt has occurred but does not execute the GOSUB until BASIC has completed executing the current BASIC program line When using the ADC library in interrupt mode and an ADC interrupt has occurred if the time to complete the current BASIC program line plus the time to execute the GOSUB plus the time to execute all the BASIC lines until the ADC library Input routine actually takes the reading from the ADC card Update 3 July 1988 1 21 Using the Library exceeds the pace interval time the ADC library will return an error 857 indicating that a reading was missed Therefore the time to service the interrupt depends upon the BASIC program line that is executing when the interrupt occurs as well as the code path to the ADC library Input routine For the faster interrupt servicing in BASIC the following tips are offered 1 2 3 4 5 Make the ADC library Input routine the first statement in the interrupt service routine Keep the interrupt service routine short Remember that the pace interval period starts with the Input routine but cannot be serviced until the interrupt service routing RETURN statement has been executed Avoid BASIC instructions which take long times to execute like input output operations or matrix operations on large arrays Avoid other interrupt processing at a higher priority than the ADC interrupt service routine Set the 98640A ADC card at the highest physical in
101. the procedure call as real integer or shortint or string variables or as constants or literal constants For all array parameters make sure that the array elements are of the correct type real or shortint do not substitute integer for shortint And take care that the size parameter you pass for an array does not exceed the actual size you declared for that array If you exceed the declared array size you can write all over the other variables in your program and cause yourself much anguish Once your Pascal program has been written and compiled it must be merged or linked to the Measurement Library using the Pascal system librarian program Be sure to transfer ALL the modules in MEAS_LIB or MEAS_LIB3 If IO is not in your system library file you will also have to transfer the module IOCOMASM from the file IO found on your LIB disc Interrupt mode operation is not supported in the Pascal environment That means we don t guarantee that it will work If you try it and it doesn t work you can purchase consulting services from the nearest HP sales and service office See the back section of this manual for a list of sales and service offices An interrupt service routine ISR is required for interrupt mode to work in Pascal and we do not provide a Pascal ISR with the Measurement Library If you try to use interrupt mode in Pascal without a proper ISR you will probably crash your system If you re an experienced Pascal programmer you ma
102. tine calls referred to below are described in detail in Section 2 of this manual Setting Up Setting up an ADC card for readings requires allocation of a common area as well as calls to at least three subroutines Meas_ lib init Config 0 and Init The common area serves as the heap space for the subroutines in the Measurement Library It is allocated automatically in Pascal in BASIC you must allocate it explicitly at the beginning of your program Reserve this area by including the following statement in your program 20 COM Heapcom INTEGER Heaparea 1 n where n is the size of the Heaparea array The size of Heaparea is determined by the number of configured names for ADC cards more about that later and the number of readings taken for calibration ditto Use 53 integers for each ADC card configuration and 4 integers for each reading used in calibration We recommend using Heaparea 1 1300 this allows all 16 possible ADC card configurations and a calibration run of 100 readings In both BASIC and Pascal the subroutine calls to Meas_lib__init Config _0 and Init do the following Meas _lib__init initializes the Measurement Library and must be called before any other subroutines in the library are called Meas_lib_ init needs to be called only once in your program Config 0 sets up an ADC card for taking readings At a minimum you specify a name by which you will call the card and the model number of the card In addition you can s
103. ubroutine call in step 3 The subroutine will return to your application program only after all requested readings have been taken As indicated in step 4 each subroutine call you make requires that you wait the set up time before pulsing the EPCON line to take the first reading For Input or Read_channel calls made in normal mode that means that you must wait the set up time before each reading If you re using Input in interrupt mode the set up time is required only before the first reading Keep in mind however that the EPCON pulses should be at least 36 milliseconds apart if you re operating in interrupt mode Bursts of Readings The idea behind taking readings in bursts is that you request multiple readings with a subroutine call and then take those readings in one burst by setting EPCON low until all of the readings have been taken These readings can be taken at the free run speed of the card or they can be paced by the card s internal pacing timer The following steps are for triggering burst readings that are paced by the internal pacing timer 1 Set IPACDA and EPCON high 2 Make a read request by issuing a call to Sequential__scan or Random__scan 3 Wait You should wait for at least the set up time plus the pace interval 4 Set the EPCON line low The analog to digital conversion for the first reading will start in approximately 3 microseconds Set the IPACDA line low This must happen 1 to 15 microseconds after you set
104. urement Library provides a set of easy to use subroutines for taking readings from the HP 98640A Analog to Digital Converter ADC card These subroutines can be used from the BASIC or Pascal language systems on the HP 9000 Series 200 computer The subroutines are written in Pascal and are adapted to the DASIC language with the CSUB utility package The Measurement Library is compatible with BASIC 2 1 BASIC 3 0 Pascal 2 0 Pascal 2 1 and Pascal 3 0 The Measurement Library subroutine calls are a superset of the HP 14751A Computer Aided Test Programming Package for the Model 6944A BASIC programs written using the HP 14751A routines should be able to use the Measurement Library software with very little modification Features The HP 98645A Measurement Library allows you to Take a single reading from any of 8 channels at any of 4 gains Take readings by scanning across 1 to 8 channels any number of times Take readings from channels in random order as specified in an address array Optionally you can specify the gain and pace interval for each reading and the readings can be repeated any number of times Express readings in three different units Base units binary integer returned from the ADC Standard units base units adjusted for gain and calibration expressed as real numbers User units standard units times a user multiplier plus a user offset Take calibration zero readings on a specified channel and apply that calibration adju
105. y attention to it since the software takes care of it all Note that since each subroutine call incurs the extra time required for two readings it is difficult if not impossible to maintain accurate and even pacing of readings between one subroutine call and the next If your application requires accurate pacing for a block of readings we suggest that you make all of those readings with one subroutine call Use Sequential_scan or Random__scan as appropriate to your application For readings taken in interrupt mode the Measurement Library software does not take care of the pipeline for you You must keep track of which readings are which not a very taxing operation and throw out the garbage More information on interrupt mode programming is contained later in this section Overrange Errors You can encounter two kinds of overrange conditions with the ADC card normal mode overrange and common mode overrange Normal mode overrange occurs when the input voltage exceeds the range of the analog to digital converter Common mode overrange occurs when either side of the differential input voltage exceeds the maximum input voltage of its input amplifier The next several paragraphs explain how these overrange conditions can affect your readings The voltage measured by the ADC card is the differential input voltage between the Input and Input terminals of a channel on the card The two sides of the input signal pass through separate input
106. y be able to write your own ISR For more information on ISRs refer to the Pascal 2 0 System Designer s Guide part number 09826 90074 WRITING THE PROGRAM In both BASIC and Pascal writing your application program involves two major activities setting up the card to take readings and taking the readings In addition BASIC programs may take readings in Using the Library interrupt mode We will cover these subjects in the paragraphs that follow We will also say a few words about externally paced readings All of the subroutine calls referred to below are described in detail in Section 2 of this manual Setting Up Setting up an ADC card for readings requires allocation of a common area as well as calls to at least three subroutines Meas lib_ init Config__0 and Init The common area serves as the heap space for the subroutines in the Measurement Library It is allocated automatically in Pascal in BASIC you must allocate it explicitly at the beginning of your program Reserve this area by including the following statement in your program 20 COM Heapcom INTEGER Heaparea 1 n where n is the size of the Heaparea array The size of Heaparea is determined by the number of configured names for ADC cards more about that later and the number of readings taken for calibration ditto Use 53 integers for each ADC card configuration and 4 integers for each reading used in calibration We recommend using Heaparea 1 1300 this

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