ClO-DAS16/Jr USER'S MANUAL - wwwpub.zih.tu
Contents
1. 4 4 5 6 PACER CLOCK CONTROL REGISTER 7 8 Wh ae 5 5 3 d d 7 3 LOW PASS FILTERS 7 4 A D RESOLUTION amp ENGINEERING UNITS 7 5 CURRENT LOOP 4 20 MA cette troop eccesso NOISE Ghi inq ER cane Table of Figures TEST Program Digital to A D loopback 1 Base address switch at 300H AY 2 2 XTAL jumper block in 1 MHz position 3 Channel Select decies ceteri 3 TEST Progarm Digital to A Dloop back eese TT 4 CIO AD16Jr Board layout showing calibration EIOS e PET 7 Analog 37 pin connector pin outs sssaaa 9 Single Ended input signal connection 10 Floating Differential signal connection t 10 Differential signal connections sn eee namannmen 11 CIO AD 16Jr board potentiometer and jumper locations aun 12 8254 Counter Timer and control register Mit I ME 17 8254 Counter Timer and control register s tdmen E 19 DMA level select switch 20 Voltage divider schematic 22 Differential dose coyote equ E EE 24 Single ended inputs 24 Common mode range graph eet e eO 25 Low pass filter schematic nnmnnn 22. anor 2 215 52 4 5 174 508 vivo 59125191 580904 ene StISTPL uvguorg 233314 4402 022 aka 4 lt TY 52151790 51517191 ota tuova 15246 NYENOIG 4 85215191 15174 otn 85215191 ofa 581519 twr uwvsxova 2 1 2 dO iLaaHS 16 12 4 12149 5 581845 NOISaq 01512 4 WHOMLYY 54047444 DILYHZHIS 1480 0400 WYEI2STW 5s WYSO IGNM oas cag LETSTPC ozn 440 912 HOLIIOGY auttasva cto sta 90519 069519 rostl 40 1 5 6 18 0 W2104M02 1661 14914440 VOd uP9T1 SVGd 4125 a 4120442 40904152 ino 521925 1534 WOLSND 21004 t a 5 ualndWO2 52009 2 14 ve onra 57 XuoMLuY 5 54081484 IILVHAHIS H S 418INO 005191 sta IY NIA ios HYSOG YM NIA 4489 2 5 CYH uvascs ras WYS
3. Coding Overvoltage Input Current Input Impedance Temp Coeff Type om Conversion Time Model 6 6 SPECIFICATIONS 450mA MAX 375 Typical OV 8 Differential 16 Single Ended 12 Bits 1 part in 4095 0 01 of reading 1 bit 10 0 625 MIN See table in section on Analog Input Bipolar Offset binary Unipolar True binary 35V continuous 250 12 nA Min 25 degC 10 Meg Ohm Full Scale 225 ppm deg MAX Zero 212 ppm dec CMAX Successive Approximation 3 uSec MAX Monotonicity Guaranteed over operating temp range Linerarity 1 Bit Zero drift 10 ppm deg MAX Gain drift 230 ppm deg MAX Vref Output 5V 0 05V PROGRAMMABLE TIMER Type 82C54 Counters 3 16 Bit down counters 2 dedicated to A D pacer XTAL 1 or 10 MHz Output Drive 2 2 0 45V Input TTL Frequency DC to 10MHz Active count edge Negative Clock pulse width High 50 8 Low Input only 4 bits 74LS244 Output only 4 bits 74LS374 Input low volts 741 5244 0 8 Input high volts 7415244 2 0V MIN 20uA Output low volts 7415374 0 5V MAX 8 0mA Output high volts 7415374 2 4V MIN 0 4mA INTERRUPT Level 2 7 Software programmable Enable INTE Bit CIO DAS16 JR Control register Trigger On board 8254 pacer clock External User supplied TTL pulse DMA A D TRANSFER Level lor3 Switch selectable Enable Bit CIO DAS16 JR Control register Termination Single Cycle Interrupt on terminal count Recycle
4. PRETI SEEN emet EEE 722 T sus VENERE 6 3 DIGITAL INPUT amp OUTPUT There are 4 bits of output only and 4 bits of input only on the CIO DASIG JR analog connector From the original DAS 16 design these were the only 8 bits of digital For complete programming information turn to the section on CIO DAS16 JR registers 6 3 1 OUTPUT The output bits are part of chip U39 a 74LS 197 output buffer The other half of the chip is used for on board control If the digital output lines are blown by overload or high voltage connection you may replace this chip 6 3 2 INPUT The input bits are part of chip U38 a 74LS244 buffer The other half of this chip is used for on board functions This chip is socketed 6 4 INTERRUPT amp TRIGGER CONTROL The interrupt and trigger control of the CIO DASI6 JR is accessible via CIO AD16 8254 PACER CLOCK amp CONTROL programming at register BASE 9 pee and is really quite simple Interrupts CONTROL REGISTER are enabled by setting The BASE 10 bus interrupt number 2 to 7 is register TRIG CTRO CTROIN OUT 2 programmed The source either from the 8254 or external is pro grammed also 10 MHz 1 00 o iin BASE ADDRESS 9 A read and write register READ INTE 1 Interrupts are enabled An interrupt generated will be placed on the PC bus interrupt leve
5. 1 LSB check the 12V PC power supply voltages or call Computer Boards Tech Support SIGNAL WIRE NOISE Signal wires especially single ended inputs are subject to EMI and RFI both of which can induce noise on the wires carrying the transducer signal to the CIO AD board Fortunately signal wire noise is often localized and can be reduced by repositioning the signal wire run To check for signal wire noise first short analog channel 0 to low level ground at the connector and take 10 000 samples and plot the histogram This is the best the signal can be and is what you will try to achieve with the signal wires in place After you have an ideal case histogram remove the short between analog input 0 and low level ground Attach the signal wires to the CIO AD board inputs and run them to the sensor Do not connect the sensor yet just short the analog input s to LLGND Take data for the histogram and compare it to the best case data taken previously If it shows noise you can try to eliminate the noise by doing the following Move the signal wires trying to locate a quiet run Use a shielded twisted pair as the signal wire Attach the shield at the PC only If the shield is attached at both the PC and the sensor it may create a ground loop and add to signal interference SENSOR NOISE When the signal wires have been tested and characterized for signal quality connect the sensor and provide a known level to the sensor ic
6. CIO DAS16 Jr SER S MANUAL REVISION 2 January 1994 amp InstaCal Disk Computer Boards Inc 125 High Street 6 Mansfield MA 02048 508 261 1123 FAX 261 1094 C 1991 1994 Computer Boards Inc COPYRIGHT NOTICE This document and all the diagrams are the property of Computer Boards Inc and may not be reproduced or copied by any means or for any purpose Table Contents t QUICK START ditione canal 1 2 INSTALLATION 2 2 1 ADDRESS mmn 2 2 2 DMA LEVEL SELECT 2 2 3 1 10 MHz XTAL JUMPER 2 2 4 8 16 CHANNEL SELECT 3 2 5 INSTALLING THE CIO DAS16 JR IN THE COMPUTER 3 2 6 PROGRAMMABLE RANGE AND GAIN SETTING eee T 4 2 7 SIGNAL CONNECTION TO TEST THE INSTALLATION 4 3 SOFTWARE INSTALLATION 5 5 SIGNAL CONNECTION 9 5 1 CONNECTOR DIAGRAM 9 Dae ANALOG N UTS tarsus 9 5 2 1 SINGLE ENDED Gee 10 5 2 2 FLOATING DIFFERENTIAL 10 5 2 3 DIFFERENTIAL 10 ANALOG INPUT RANGE REGISTER PACER CLOCK DATA amp CONTROL REGISTERS ALOG INPUT SU OUTPUT 6 3 2 INPUT 6 4 INTERRUPT 4 TRIGGER CONTROL 6 5 DMA CONTROL LOGIC
7. s analog or digital inputs The key term in a low pass filter circuit is cut off frequency The cut of frequency is that frequency above which no variation of voltage with respect to time may enter the circuit For example if a low pass filter had acut off frequency of 30 Hz the kind of interference associated with line voltage 60Hz would be filtered out but a signal of 25Hz would be allowed to pass Also in digital circuit a low pass filter might be used de bounce input from a momentary contact button pushed by a person A low pass filter may be constructed from one resistor R and one capacitor C The cut off frequency is determined according to the formula LOW PASS FILTER 1 SIGNAL HIGH R A D BOARD Ra HIGH INPUT 2 Pi R C 1 dE E 2 Pi R C Re 2 Pi C F AID BOARD SIGNALLOW Y LOW INPUT 7 4 A D RESOLUTION amp ENGINEERING UNITS Resolution is specified in bits such as 8 10 or 12 bits The 12 bits are really a power of 2 indicating the number of divisions of full scale the converter can resolve For example a 12 bit converter can resolve 2412 1 4095 divisions of full scale If the input of the board were 5 volts full scale each of the 4095 steps would be equal to 0 00244 volts Reading from the A D converter would be thus To translate the A D numbers back into the engineering units of the original measurement we need to know The sensor s volt
8. 1 2 5 1 0 0 1 0 1 25V 2 0 0 1 1 0 625V 3 0 1 0 0 0 10V 4 0 1 0 1 0 5V 5 0 1 1 0 0 2 5V 6 0 1 1 1 0 1 25V 7 Of course the bits and control words are only of interest to programmers Applications software takes care of programming the analog input range for you as does the calibration program For those wishing more information on programming the analog inputs examine the section of register base 11 and the section on BASIC programming 2 7 SIGNAL CONNECTION TO TEST THE INSTALLATION To test the installation of the CIO DAS16 JR there must be electrical signals for it to read and display You can supply the signal with a function generator or other voltage soyrce or you can loop back the CIO DAS16 JR output signals onto the CIO DAS16 JR inputs Please before you connect a voltage from a signal generator or other source be sure that the signal does not exceed 10V the maximum analog input range of the board or 0 5V the maximum digital input range The analog inputs are protected to 30V but why prove it Supplied with the CIO DAS16 JR are some wires with plugs on each end These are intended to be plugged directly on the CIO DAS16 JR 37 pin connector for anew loop back testing If you purchased a screw terminal then connect it up and use 919 it instead To test the installation of the CIO DAS16 JR the digital output 0 will be looped back into the A D 0 input If you are using a signal generator feed th
9. Pacing Internal 8254 pacer clock External User supplied TTL pulse POWER Direct from PC bus See you PC spec Voltage 5V 559 Depends on PC power Loading 22AWG 64 9 Ohms 1000 feet CIO DASIG JR Normal Temp Model Operating Temp 0 to 50 Deg C Storage Temp 20 to 70 Deg C Humidity 0 to 90 non condensing Weight 10 25 Oz CIO DAS16 JR Extended Temp Model Operating Temp 30 to 60 Deg Storage Temp 165 to 150 Deg Humidity 0 to 90 non condensing Weight 10 25 Oz Page 21 7 ANALOG ELECTRONICS This short simple introduction to the analog electronics most often needed by data acquisition board users covers a few key concepts They are Voltage dividers Differential vs Single Ended Inputs Isolation vs Common Mode Range Low pass filters for analog and digital inputs A D Resolution Conversion to Engineering units 4 20 inputs Noise sources and solutions Digital interfacing Each deals with the impact on measurements made with data acquisition boards If you are truly interested in the subject of data converters and analog electronics Radio Shack has written an excellent Op Amp handbook and has an Op Amp experimenters kit more advanced treatment may be found in the Analog Digital Conversion Handbook 32 95 and the Transducer Interfacing Handbook 14 50 published by Prentice Hall 7 1 VOLTAGE DIVIDERS If you wish to measure a signal which varies over a range greater than th
10. inputs of the CIO DAS16 JR may be configured as 8 differential or 16 single ended Using single ended inputs means you have more separate analog input channels available to connect signals Using differential inputs allows up to 10 volts of common mode ground loop rejection and can be more noise immune The CIO DAS16 JR comes from the factory configured for 8 differential inputs so the 8 16 switch is in the position shown here Set it for the type 8 16 CHANNEL SELECT and number of inputs you desire 8 DIFFERENTIAL INPUTS SELECTED 2 5 INSTALLING THE CIO DAS16 JR IN THE COMPUTER Turn the power off Remove the cover of you computer Please be careful not to dislodge any of the cables installed on the boards in your computer as you slide the cover off Locate an empty expansion slot in your computer M M 3 See the explaination of MODE 0 in the section on BASIC CALL software Page 3 Push the board firmly down into the expansion bus connector If it is not seated fully it may fail to work and could short circuit the PC bus power onto a PC bus signal This could damage the motherboard in your PC as well as the CIO DAS16 JR 2 6 PROGRAMMABLE RANGE AND GAIN SETTING The CIO DAS16 JR analog input range is fully programmable The range is set by writing to a register at base address 11 The 4 lower bits of that register correspond to settings of Range Uni Bip 01 00 Input Range Decimal 1 0 0 0 10V 8 0 0 0 0 5V 0 0 0 0
11. the 8254 It can also be used as the source of an external start conversion pulse synchronizing A D conversions to some external event When written to The upper four bits are ignored The lower four bits are latched TTL outputs Once written the state of the inputs cannot be read back because a read back would read the separate digital input lines see above 6 1 4 STATUS REGISTER BASE ADDRESS 8 308 HEX 776 Decimal A read mostly one function write register READ EOC 1 the A D converter is busy EOC 0 it is U B 1 the amplifier is in Unipolar mode U B 0 is bipolar MUX 1 Channels are configured 16 single ended MUX 0 8 differential INT 1 an external pulse has been received INT 0 the flip flop is ready to receive a pulse There is a flip flop on the TRIGGER input pin 25 which will latch a pulse as short as 200 nanoseconds Once triggered this flip flop must be reset by a write to this register Your interrupts service routine must do this before another interrupt trigger can be received CH8 CH4 CH2 amp CHI are a binary number between 0 and 15 indicating the channel number that the MUX is currently set to and is valid only when EOC 0 The channel MUX increments shortly after EOC 1 so may be in a state of transition when EOC 1 The binary weight of each bit is shown in the table above WRITE A write of any data to this register resets the flip flop on the pin 25 input and set
12. 0 When CTRO 0 the input to 8254 Counter 0 is entirely dependent on pulses at pin 21 COUNTER 0 CLOCK INPUT TRIGO 1 When TRIGO 1 the TRIGGER input at pin 25 is ANDed with TRIGO which must therefore be high for the pulses from the on board pacer clock 8254 to start A D conversions The input at pin 25 is pulled up and will always be high unless pulled low externally TRIGO 0 When TRIGO 0 the GATEs of counter 1 amp 2 are held high preventing any pulses from acting as source of A D start pulses The following diagram may help understand these registers and is further explained in the section covering the 8254 6 Information on the assignment of interrupt levels to standard PC peripherals is found in the section on the architecture of the PC In other words not all interrupts 2 7 are available without conflict 7 An example of how to set up the DMA controller may be found in the BASIC CALL source code The code is the same for PC XT AT and 386 The source code is for sale only after executing a non disclosure agreement Please contact our technical support for a copy of the agreement 16 CIO AD16 8254 PACER CLOCK amp CONTROL 5V 5V CONTROL REGISTER 10K BASE 10 TRIG CTRO CTROIN CTR 2 OUT TRIGGER 6 1 7 ANALOG INPUT RANGE REGISTER BASE ADDRESS 11 30B HEX 779 Decimal A write to this register sets the analog input range for all 8 16 analog input
13. 028 0 0 1 4 9976 0 5 0 The concept of resolution is the ability to differentiate between one voltage and another Obviously the more bits of resolution 13 bits 8192 counts the more divisions of full scale The more divisions of full scale the finer the measurement ENGINEERING UNITS When a program uses an A D board to acquire data the data file is filled with numbers like those above Page26 5 volts 0 02 Amps 250 Ohm shunt resistor So a full 20 mA will register 5 volts and 4 mA will register volt To hook up the CIO AD analog inputs to a 4 20 mA transducer or signal source place the shunt resistor across the plus and minus terminals or signal wires of the 4 20 mA Once the resistor is in place connect the analog input CH Hi to the plus terminal and the analog input CH Lo to the minus input If they are backward the A D reading will be 0 or minus volts Just reverse the connection A D BOARD HIGH INPUT Vin A D BOARD 4 LOW INPUT Page 27 7 6 NOISE Noise is unavoidable in PC based data acquisition systems There is board induced noise which be measured by shorting an analog input to ground and taking a series of readings and plotting them in a histogram There is EMI and RFI induced noise along the path of the signal wires There is also noise at the signal source itself All these sources of noise combine to create a region of uncertainty around the signal value O
14. 32 bit boundary After a base address is chosen a diagram of the switch setting is drawn on the PC screen Set the switches on your base address switch as shown on BASE ADDRESS SWITCH the diagram Unless there is already a board in your system which uses address 300 HEX 768 Decimal then you can leave the switches as they are set at the factory SETTINGS SHOWN ARE FOR 300 HEX 768 DECIMAL In the example shown here the CIO DASI6 JR is set for base address 300H 2 2 DMA LEVEL SELECT What kind of computer are you installing the board in If it is an XT then there are only two DMA levels available and level 3 is probably used by the hard disk controller in your XT computer Set the DMA level switch to the level 1 position If you have an AT or 386 type computer the hard disk controller is not at level 1 or3 so either level may be used LEVEL 1 IS SELECTED There are other boards that use DMA levels Some network boards do and so do some IEEE 488 interface boards Do you have other boards in your computer with DMA level switches on them 2 3 1 10 MHz XTAL JUMPER M 1 The CIO DAS16 JR base address must be on a 32 or 16 bit boundary because of the architecture of the address decode logic Please refer to the section of this manual on the architecture of the CIO DAS16 JR for an explanation of why this is so 2 This program attempts to locate conflicts but can only do so if the device occupying th
15. 6 Schematic of 4 20 mA to analog 27 CIO AD16Jr Signal Connector 32 32 DMA level select switch 32 8 16 channel select switch 32 XTAL clock speed jumper eme EN T 32 The CIO DAS16 JR is easy to use Here is the quick start procedure for those who know how to open the PC an install expansion boards and want to dive right in 1 8 BOARD SETUP The CIO DAS16 JR is setup at the factory with BASE ADDRESS 300H 768 Decimal Same as data sheet DMA CHANNEL SELECT 1 Choices are 1 amp 3 3 is used by the hard disk in an XT 1 10 MHz jumper 1 MHz 8 16 CHANNEL SELECT GAIN RANGE Programmable Power on default is 5 volts Insert the CIO DAS16 JR UTILITY disk in drive Answer your software Program setup questions w your disk has a CIO DAS16 JR installed Software and drivers are also pre SIGNAL CONNECTION 1 1 i 8 Differential input channels 1 1 ith the information above The LABLOG II program shipped with So does the LabTech Acquire program The Compatible I O Series utility configured 37 CHO HIGH 22 The board is factory configured in differential input mode Differential Input mode requires 3 connections be made om the si gnal source to the CIO DAS16 JR The
16. 6 1 2 CHANNEL MUX SCAN LIMITS REGISTER BASE ADDRESS 2 302 HEX 770 Decimal Bg wr 20112112 A read and write register READ The current channel scan limits are read as one byte The high channel number scan limit is in the most 5 gnificant 4 bits The low channel scan limit is in the least significant 4 bits WRITE The channel scan limits desired are written as one byte The high channel number scan limit is in the most significant 4 bits The low channel scan limit is in the least significant 4 bits That is one way of looking at this register and probably the most sensible way In fact the bits 3 0 contain the starting channel number and bits 7 4 contain the ending channel number If you wanted to scan channels 1 2 3 that order you could do so by placing 3 bits 7 4 and the 1 in bits 3 0 NOTE Every write to this register sets the current A D channel MUX Setting to the number in bits 7 4 See BASE 8 6 1 3 4 BIT DIGITAL REGISTERS BASE ADDRESS 3 303 HEX 771 Decimal Pagel4 When read 1 The signals present at the inputs are read as byte the most significant 4 bits of which are always zero The pins 25 digital input 0 and 24 digital input 2 digital inputs have two functions each The TRIG function of digital input 0 may be used to hold of the first sample of an A D set by holding it low until you are ready to take samples which are then paced by
17. ED INPUTS Two type of analog inputs are commonly found on A D boards they are differential and single ended Single ended is the less expensive of the two COMMON MODE RANGE Page 23 Differential inputs have common mode range CMR Single ended inputs have CMR Common mode range is the voltage range over which differences in the low side of the signal and A D input ground have no impact on the A D s measurement of the signal voltage A differential input can reject differences between signal ground and PC ground Shown here is a CIO DAS16 JR in differential mode single ended input has common mode range because there is only one LOW wire which is assumed to be at the same level at the signal and at the A D board Page24 The maximum difference which may be rejected DIFFERENTIAL INPUT DIFFERENTIAL is the CMR AMP Imm For example the CIO DAS16 Jr has a common mode plus signal range of 11 5 volts common mode not to exceed 10 volts EX 1 MAX CMR SIGNAL CUMULATIVE SIGNAL RANGE This specification is illustrated graphically here 11 5 and will be referred to as Cumulative Signal Range CSR PC GROUND EX 2 MAX CMR SIGNAL UNUSED CMR 3 5V Vgl 4 GROUND DIFFERENTIAL AMP Most manufactures of A D boards specif
18. IO VYM 5 9 HELPFUL DIAGRAMS 5 SHEET 5 CIO AD16Jr CONNECTOR COMPUTER BOARDS DAS 16JR PGA COPYRIGHT 1991 COMPUTER BOARDS INC CUSTOM DESIGN SERIES SCHEMATIC REFLECTS REV 5 ARTWORK LLGND 19 CHO LOW CHB HIGH 18 CHI LOW CH9 HIGH 17 2 LOW CHIOHIGH 16 5 5 CH3 LOW 11 HIGH 15 a CH4 LOW CH12 HIGH 14 cra Hian Sg CHS LOW CHI3HIGH 13 os F CH6 LOW CHI4HIGH 12 LOW CHI5 HIGH 11 NC 10 2 lac 5 NC 9 ar 5 GNO 7 DIG IN 0 TRIGGER DIG INT 6 E DIG IN2 08 143 5 DIG OUT 0 5 1 DIG OUT1 4 Di QUIA I DIG OUT3 3 CTROCLOCK IN CTROOUT 2 GA ZOUT 5VPCBUS 1 BASR11RD RA DOBAR RDI OBAR MA2 OUTB 4 HEOR BASE ADDRESS SWITCH SETTINGS SHOWN ARE FOR 300 HEX 768 DECIMAL DMA LEVEL SELECT me a PLUS LOGIC CBI CUSTOM DMA LEVEL 1 IS SELECTED w 4 n a n 2222 XTAL JUMPER Default 1MHz Shown MHZ 8 DIFFERENTIAL INPUTS SELECTED Page32
19. age output per engineering unit The full scale range of the board at the time the measurement was made The resolution of the converter Here is an example from the application note on interfacing a Voland TA to a PC found elsewhere in this manual The TA measures resistance in grams between 500 and 500 grams The voltage output of the instruments is 42 5 volts to 2 5 volts The voltage output corresponds to the grams of pressure exactly so 500 grams 1000 grams 2 5 volts 5 volts 5 volts 1000 grams 0 005 volts per gram The A D was set for 2 5 volts 5 volts full scale 5 volts 4095 counts 0 00122 volts per bit If the number in the file for one reading was 3061 then 3061 0 00122 3 7632 volts 3 7632 volts 0 005 volts per gram 735 grams Now shift from full scale to scale 735 grams full scale 500 235 grams of positive pressure It may look like a lot of steps because it is presented that way here for clarity only It could be expressed as a single equation in a spreadsheet 7 5 CURRENT LOOP 4 20 mA Although the inputs of a CIO AD board are voltage inputs it is easy to convert a current to a proportional voltage which may be measured by the CIO AD board The current is converted to a proportional voltage by the formula V I R For example if the CIO AD board is set up to read 0 to 5 volts then 4 20 mA TO VOLTAGE CONVERTER Converter Volts 4095 5 0 4094 4 9976 4093 4 9951 2
20. ble are identical to the DAS 16 an additional signal SS amp H OUT may be accessed at pin 26 CIO AD16Jr CONNECTOR The connector accepts female 37 D type connectors such as those on the C73FF 2 2 foot cable with connectors CHO LOW CH8 HIGH CHO HIGH CH1 HIGH CH1 LOW CH9 HIGH CH2 HIGH If frequent changes to signal connections or signal condi CH2 LOW CH10 HIGH CH3 HIGH nine CH3 LOW CH11 HIGH tioning is required please refer to the information on the CHa LOW HIGH CH4 HIGH CIO TERMINAL screw terminal board CIO MUXTC32 cus LOW CH13 HIGH 2 CHS HIGH 32 channels analog MUX AMP CIO SSH 16 16 channel LOW CH14 HIGH pie simultaneous sample amp hold board or the 8 CH7 LOW CH15 HIGH LEGND and 6 10 cable 5B module interface rack LLGND NC SS amp H OUT DIG IN 0 TRIGGER DIG IN 2 DIG OUT 0 DIG OUT 2 CTR 0 CLOCK IN 2 OUT om 5V BUS 5 2 ANALOG INPUTS Analog inputs to the CIO DAS16 JR may be connected in three different configurations In order of complexity these are Single Ended Floating Differential and Differential WARNING PLEASE READ Here is a good tip Measure the voltage potential difference between the ground signal at the signal source and the PC Use a volt meter and place the red probe on the PC ground and the black probe on the signal ground If there is a difference of mo
21. board 3 Check the voltage between the signal ground and the PC ground It should be 0 volts 4 Check other boards in your PC for address and interrupt conflicts 5 Check that the CALL routine is in the directory where your BASIC program is 6 Refer to the example programs for techniques and as a baseline to check code against PLEASE NO RETURNS WITHOUT RMA NUMBERS CALL 508 261 1123 Please and here is why It slows down the solution of your problem If we receive a return without an RMA number written on the outside of the box a Tech Support person will call you before any work is done so we can determine the reason for the return We need to know what you want us to look for Page30 The RMA system is fully automated and all the Tech Support engineers have access to the information in it They can track your RMA and discuss your return history with you This is very valuable if the setup you are using i i inputs We can spot that and discuss a solution HARSH ENVIRONMENT WARRANTY Ifa been short circuited and visibly burnt or otherwise damaged beyond repair return the board to us with an order for a replacement There is a very large discount on th ich is specified in current Compatible Series catalog The entire CIO board must returned with components in place with a purchase order for the replacement boards are used in harsh environm
22. dress or BASE ADDRESS is determined by setting a bank of switches on the board A register is easy to read and write to Most often register manipulation is best left to ASSEMBLY language programs as most of the CIO DAS16 JR possible functions are implemented in easy to use BASIC CALL routines PASCAL C FORTRAN libraries The register descriptions follow all follow the format Lr we owe A D10 11 A D12 CH8 LSB f o Page12 SERE SERERE HORAS hse xd 1 npe N i Where the numbers along the top row are the bit positions within the 8 bit byte and the numbers and symbols in the bottom row are the functions associated with that bit To write to or read from a register in decimal or HEX the following weights apply BIT POSITION DECIMAL VALUE HEX VALUE 0 1 1 1 2 2 2 4 4 3 8 8 4 16 10 5 32 20 6 64 40 7 128 80 write control data to a register the individual bits must be set to 0 or 1 then combined to form a Byte Data read from registers must be analyzed to determine which bits are on or off The method of programming required to set read bits from bytes is beyond the scope of this manual It will be covered in most Introduction To Programming books available from a book store In summary form the registers and their function are listed on the follo
23. e base address you have chosen has read back registers Page2 The 1 10 MHz XTAL jumper selects the frequency of the square wave which is connected to OUT 2 the output of 8254 counter 2 Counter 2 is XTAL J U M used to pace the A D start conversion trigger Default 1MHz Shown Why is this jumper on the board Because the original DAS 16 designed in 1984 had a 1 MHz crystal When MetraByte redesigned the DAS 16 and added the faster 10MHz crystal a jumper was provided to maintain compatibility with older software The CIO DAS16 JR has the jumper because the DAS 16 has the jumper and some software expects the jumper to be in the 1 MHz position and some software expects the 10 MHz position The CIO DAS16 JR is shipped with the jumper in the 1 MHz position The BASIC CALL routine CIO16 allows you to specify a 1 or 10 MHz position in the setup Certain MODES 50 and 51 for example allow the sample rate to be specified in Hz rather than having to independently set the counter speed To calculate the counter load values the counter 2 input frequency must be known Some software programs such as UNKELSCOPE ASYST and ASYSTANT require that the jumper be in the 1MHz position Please refer to the software program user s manual for guidence Othe programs such as Labtech Notebook have a 1 10MHz choice in the set up menu 2 4 8 16 CHANNEL SELECT The analog
24. e bath for temp etc then take data for the histogram plot If additional noise has been introduced by the sensor which exceeds the sensor specifications you can try moving the sensor or electrically isolating it from the device it is measuring 9 Differential inputs must have CH Hi CH Lo and LLGND shorted Single ended inputs must have CH Hi shorted to LLGND Page28 Sesion EUN senes Wisin 4 caren D SMOOTHING DATA It is not always possible to eliminate all noise especially with very low level sensors but noise looks terrible when plotted and can raise doubts about otherwise excellent data There are two simple ways to eliminate noise from the data 1 Apply a moving average to the data if you want to retain the same apparent accuracy 2 Remove the information from the noisy range For example if the A D is capable of or shift the data by the number of counts of noise For example if a 12 bit A D converter is at 5 volts 10 volts full scale then one LSB 10 4095 0 00244mV If your system is inducing 0 007mV of noise 4 3 counts then just round all the readings by 3 counts In this way the reading s value reflects the true accuracy of the system Page 29 8 DIAGNOSIS amp DEBUG Computer Boards maintains technical support lines staffed by experienced Electrical Engineers and Technicians There
25. e input range of an analog or digital input a voltage divider can drop the voltage of the input signal to the level the analog or digital input can measure A voltage divider takes advantage of Ohm s law which states Voltage Current Resistance and Kirkoff s voltage law which states The sum of the voltage drops around a circuit will be equal to the voltage drop for the entire circuit Implied in the above is that any variation in the voltage drop for the circuit as a whole will have a proportional variation in all the voltage drops in the circuit A voltage divider takes advantage of the fact that the voltage across one of the resistors in a circuit is propor tional to the voltage across the total resistance in the circuit The trick to using a voltage divider is to choose two SIGNAL HIGH resistors with the proper proportions relative to the full scale of the analog or digital input and the maximum signal voltage A D BOARD HIGH INPUT SIMPLE VOLTAGE DIVIDER A D BOARD SIGNAL LOW LOW INPUT The phenomena of dropping the voltage proportionally is often called attenuation The formula for attenuation is Page22 The variable Attenuation is the proportional difference Attenuation between the signal voltage max and the full scale of the analog input For example if the signal varies between 0 and 20 volts and you wish to measure that with an analog input with a full scale range of 0 to 10 volts the Attenua
26. e section on the counter time and the Intel 8254 data sheet 8254 COUNTER CONTROL BASE ADDRESS 15 30F HEX 783 Decimal alel oe m This register controls the operation and loading reading of the counters The configuration of the 8254 codes which control the 8254 chip is explained in the section on the counter timer and the Intel 8254 data sheet 6 2 ANALOG INPUT Analog signals connected to P3 the 37D connector which protrudes from the expansion slot of the PC are first fed into the two HI 0508 analog multiplexors A multiplexor s MUX function is to select on of several 8 inputs and connect that input to the MUX output MUX 027 connects CHO CH7 high inputs MUX U28 connects CHO CH7 Low input differential input mode or CH8 CH15 High inputs single ended mode depending on the state of the channel configuration switch located at the upper right of the board and marked 8 16 From the output of the MUX the analog signal is fed into a programmable differential amplifier The A D converter chip has an integral sample amp hold circuit greatly simplifying design and improving signal integrity The A D converter is capable of sampling rates to 330KHz but the DMA transfer circuitry of the personal computer s 8 bit bus is limited to a maximum synchronous transfer rate of about 130KHz Therefore the maximum sampling rate of the CIO DAS16 JR is up to 130KHz depending on the computer
27. e signal directly into A D channel 0 The CIO DAS16 JR is ready to test You can try running the software supplied with your board now or you can continue reading the nexttwo sections on Software Installation and Calibration The program IOTEST will display the loopback Digital output into the A D on a strip chart on the screen 4 The CIO TERMINAL and CIO MINITERM are fully explained inthe appendix Briefly the connector numbers on the screw terminals correspond to the numbers on the CIO DAS16 JR 37 pin connector Page4 3 SOFTWARE INSTALLATION InstaCal is an installation calibration and test package Use it to guide the installation procedure and to calibrate your data acquisition board InstaCal also creates a configuration file required for programmers who have purchased the Universal Library programming libraries Use the calibration option to verify the installation IOTEST may also be used to verify the installation It exercises the CIO DAS1600 by stimulating the analog and digital output ports and reading the analog and digital inputs The inputs are displayed on the screen on a line graph IOTEST can provide one output and read one input at a time The activity on an output channel is fixed by the program Analog output 0 and 1 produce a sine wave Digital outputs produce a square wave Counter outputs produce a square wave Page 5 4 CALIBRATION AND TEST The CIO DAS16 JR is supplied
28. ents and they do get damaged by misconnection We understand that and do not want to make a profit from your misfortune Page 31 540 2 LaaHs ont 1561 1M51u4402 9 5 521435 5 1041 5641 5041 7081 OWI 1081 kr Pr 18 Jos 8 tus 5 705712 AVESOLVLSY IE PE vaYabul A A A XWOMLUV 54047484 OILVHSHOS oaa tag 548 198 21 5245 TNU 86015791 ta 54151791 oot Post POSTIL divas tNIG 1104 1 a4 ONIG INIG 7150415 5 uvalasaud 0519 ato 1252904 mj wf ont SOUNO 1681 WOd urgt swa za 581445 1530 01515 12 50 14 5 1 zd st Jie TEC TES LUY 5 SL2a1424 DILYWZIHOS gino anot Lant got T 1552 Tero 5 anor anot 92
29. ge you intend to use it When the range is changed slight variation in Zero and Full Scale may result These variations can be measured and removed in software if desired Page6 CIO AD16Jr BOARD LAYOUT SHOWING CALIBRATION POTENTIOMETERS Unipolar Offset 7 Input Offset Gain Bipolar Offset CHANNEL SELECT DMA 22127 SELECT CALIBRATION PROCEDURE The entire calibration procedure is provide in the program CAL16JR EXE which is on the CIO DAS16 JR utility disk Please refer to the automated procedure if you want to calibrate your CIO DAS16 JR The calibration procedure provided here is informational only BIPOLAR OFFSET ADJUSTMENT 1 Set the gain register to the bipolar range which is likely to be used most often 2 Apply OV 1 2 LSB of the specified range to the channel 0 input 3 Adjust R4 bipolar offset pot until A D reads 0 1 counts UNIPOLAR OFFSET ADJUSTMENT 1 Set the gain register to the unipolar range which is likely to be used most often 2 Apply OV 1 2 LSB of the specified range to channel 0 input 3 Adjsut R2 unipolar offset until A D reads 0 1 counts AMPLIFIER INPUT ADJUSTMENT Page 7 1 Apply OV to the channel 0 input Shorting cahnnel 0 to LLGND pin 37 to pin 19 is ideal 2 Set the gain register to the 0 625 volt range code 3 3 Adjust R3 until A D reads 0 counts GAIN ADJUSTMENT 1 Set the gain regis
30. ial signal is three wires from the signal source CIO ECTOR 8 The signals are Signal High CH HI Signal Low CH amp 4916 CONNECTOR 8 CHANNEL DIFFERENTIAL LO and Signal Ground LLGND m A differential connection allows you to connect the CIO DAS16 JR to a signal source with a ground that is different than the PC ground but less than 10V difference and still make a true measurement of the signal between HI and CH LO EXAMPLE laboratory instrument with its own wall plug There are sometimes differences in wall GND between outlets 5 3 DIGITAL OUTPUTS amp INPUTS All the digital outputs inputs on the CIO DAS16 JR are TTL level TTL is an electronics industry term short for Transistor Transistor Logic with describes a standard for digital signals which are either at OV or 5V The binary logic inside the PC is all TTL or LSTTL Low power Schotky TTL Both specifications are presented here Digital signal connections are common and easy to understand when the simple rules presented in the section on analog electronics are applied Page 11 6 CIO DAS16 JR ARCHITECTURE CIO AD16Jr BOARD LAYOUT SHOWING CALIBRATION POTENTIOMETERS Gain To Unipolar LN Amp Input Offset 22 Bipolar Offset CHANNEL SELECT R1 R2 R3 R4 8 16 DMA SELECT 6 1 CONTROL amp DATA REGISTERS The CIO 16 is controlled and monitored by writing to and reading from 16 consecutive 8 bit I O addresses The first ad
31. is no charge to call and calls are returned promptly if you have called when the lines were busy Most of the problems encountered with data acquisition plug in boards can be solved over the phone Signal connection and programming are the common sources of difficulty and Computer Boards Tech Support people can solve these type of problems with you especially if you prepare for the call 1 Have the phone near the PC where you can try the things we suggest 2 Be prepared to open the PC remove the board and read back or change switch and jumper settings 3 Have a volt meter available to make measurements of the signals you are trying to measure and the signals on the board and PC power supply 4 Isolate the program lines that are not working as you expect them to 5 Have all the source code to the program you are having trouble with so preceding modes and prerequisite modes may be discussed 6 Have the manual ready 7 Have the Utility diskette available so the revision and programs can be checked THIS LITTLE BIT OF PREPARATION WILL SPEED DIAGNOSIS AND MAY SAVE YOU THE TROUBLE OF A CALL BACK GENERAL DIAGNOSIS If you would like to try a few things first here is a list of common problems 1 Check the PC bus power especially the 12 volts The 12 and 12 should be within 1 2 volt of 12 2 Check the voltage level of the signal between the signal high and signal low It cannot exceed the full scale range of the
32. l selected by IRA amp IRI INTE 0 interrupts are disabled 2 IR4 IR2 IR are bits in a binary number between 0 and 7 which map interrupts onto the PC bus interrupt levels 2 7 Interrupts 0 amp 1 may not be asserted by the CIO DAS16 JR 8 Information on the assignment of interrupt levels to standard PC peripherals is found in the section on the architecture of the PC In other words not all interrupts 2 7 are available without conflict 51 amp TSO control the source of the A D start conversion trigger according to the table below 1 TSO 0 X Software triggered A D only 1 0 Start on rising TRIGGER Digital input 0 Pin 25 1 1 Start on Pacer Clock Pulse CTR 2 OUT no external access 6 5 DMA CONTROL LOGIC The Direct Memory Access DMA controller is on the personal computer CPU board not on the CIO DAS16 JR The CIO DAS16 JR has the logic on board to request a DMA transfer In addition to the on board logic the DMA controller must be programmed Complete register specifications for the CIO DAS16 JR DMA control registers will be found in the previous section on the CIO DAS16 JR control registers DMA LEVEL SELECT DMA LEVEL 1 IS SELECTED A discussion of the CIO DAS16 JR DMA level selection and the PC s DMA controller will be found in the section on the architecture of the PC Page20 POWER 5 12 12 ANALOG INPUT Channels Resolution Accuracy Input Range
33. re the 10 volts do not connect the CIO DASI G IR to this signal source because you will not be able to make any reading If the difference is more than 30 volts DO NOT connect this signal to the CIO DASI6 JR because it will damage the board and possibly the computer Page 9 5 2 1 SINGLE ENDED A single ended input is two wires connected to the CIO SINGLE ENDED INPUT DIFEERENTIAE DAS16 JR a channel high CH HI and a Low Level AMP Ground LLGND The LLGND signal must be the same ground the PC is on The CH is the voltage signal source Examples are 5 2 2 FLOATING DIFFERENTIAL A floating differential input is two wires from the signal CIO AD16 CONNECTOR 8 CHANNEL DIFFERENTIAL source and a 10K ground reference resistor installed at the CIO DAS16 JR input The two signals from the signal ET source are Signal High CH HI and Signal Low CH amp LO AMP The reference resistor is connected between the CIO DAS16 JR CH LO and LLGND pins A floating differential hookup is handy when the signal source is floating with respect to ground such as a battery 4 20mA transmitter or and the lead lengths are long or subject to EMI interference The floating differential input will reject up to 10V of EMI energy on the signal wires WARNING Is the signal source really floating Check it with a voltmeter before risking the CIO DAS16 JR and PC 5 2 3 DIFFERENTIAL 10 A different
34. s The lower 4 bits set the analog input range The upper 4 bits are not used 1 nip Range Uni Bip Gl GO Input Ran Decimal 1 0 0 0 10V 8 0 0 0 0 5V 0 0 0 0 1 i2 5V 1 0 0 1 0 1 25 2 0 0 1 1 0 625V 3 0 1 0 0 0 10V 4 0 1 0 1 0 5V 5 0 1 1 0 0 2 5V 6 0 1 1 1 0 1 25V 7 To set the analog range of the CIO DAS16 JR programatically write the correct input range code to the base address 11 For example from BASIC If the board s base address is 300 HEX 768 decimal then the gain register is at 768 11 779 17 100 OUT 779 5 The decimal range codes are in the far right column above 6 1 8 PACER CLOCK DATA amp CONTROL REGISTERS Set analog output range to 0 5V 8254 COUNTER 0 DATA BASE ADDRESS 12 30C HEX 780 Decimal ps pr p ps p 8254 COUNTER 1 DATA BASE ADDRESS 13 30D HEX 781 Decimal DECRE ps 14 ps 8254 COUNTER 2 DATA BASE ADDRESS 14 30E HEX 782 Decimal coy p ps pm ps m p The three 8254 counter timer data registers may be written to and read from Because each counter will count as high as 64 536 it is clear that loading or reading the counter data must be a multi step process The operation of the 8254 is explained in th
35. s the INT bit to 0 6 1 5 DMA INTERRUPT amp TRIGGER CONTROL BASE ADDRESS 9 309 HEX 777 Decimal Page 15 A read and write register READ INTE 1 Interrupts are enabled An interrupt generated will be placed on the PC bus interrupt level selected by IRA IR2 amp IRI INTE 0 interrupts are disabled IRA IR2 IRI are bits in a binary number between 0 and 7 which map interrupts onto the PC bus interrupt levels 2 7 Interrupts 0 amp 1 may not be asserted by the CIO DAS16 JR DMA 1 DMA transfers are enabled DMA 0 DMA transfers are disabled It is worth noting that this bit only allows the CIO DAS 16 JR to assert DMA request to the PC on the DMA request level selected by the DMA switch on the CIO DASIG JR Before this bit is set to 1 the PC s 8237 or appropriate DMA controller chip must be set up TS1 amp TSO control the source of the A D start conversion trigger according to the table below TS1 TSO 0 Software triggered A D only 1 0 Start on rising TRIGGER Digital input 0 Pin 25 1 1 Start on Pacer Clock Pulse CTR 2 OUT no external access 6 1 6 PACER CLOCK CONTROL REGISTER BASE ADDRESS 10 30A HEX 778 Decimal ec Write only 1 When CTRO 1 an on board 100KHz clock signal is ANDed with the COUNTER 0 CLOCK INPUT pin 21 A high on pin 21 will allow pulses from the on board source into the 8254 Counter 0 input
36. se are SIGNAL HIGH SIGNAL LOW amp GROUND LLGNO 19 CHO LOW CH8 HIGH 18 test the analog inputs you need a known si gnal to connect to them The simplest signal to connect is the Digital Outpu t O from the CIO DASI6 R The DAS 16 compatible analo inputs are on the 37 pin connector which extends through the facep late out the back of the PC when the board is installed Using the Shorting wires su pplied with the board short pins 18 to 19 and pins 37 to 9 as shown to the right Run the program IOTEST on the InstaCal disk Select Digital output channel 0 and Analog input channel 0 You should see a slow moving square wave on the Screen The CIO DAS16 JR is installed and running correctly You may now run other programs from the utility disk or install and run LABLOG II or LabTech Acquire 2 INSTALLATION The CIO DAS16 JR has one bank of switches two single function switches and one jumper block which must be set before installation of the board inside your computer The calibration and test program included with the CIO DASI6 JR will show how these switches are to be set and should be run before you open your computer 2 1 BASE ADDRESS Menu choice number from the CALI6JR main menu is SELECT BASE ADDRESS and runs a program that allows you to choose a desired base address and adjusts the base address if necessary to place it on a
37. ter to the range likely to be used most often 2 Apply Full Scale 1 5 LSB to the channel 0 input 3 Adjust R1 gain adjust pot until for unipolar adjust to 4094 4095 counts for bipolar adjust to 2046 2047 counts 4 4 TESTING THE COUNTER TIMER amp DIGITAL VO There is no calibration to be performed on the counter timer which is crystal controlled or the digital which are TTL CALIG6JR can test the cascaded counters 1 and 2 against the system clock to ensure that they are functioning It can also stimulate the digital outputs and read the digital inputs A better dynamic test of the counters and digital I O can be performed by the IOTEST EXE program Page8 5 SIGNAL CONNECTION Signal connection can be one of the most challenging aspects of applying a data acquisition board If you are an Analog Electrical Engineer then this section is not for you but if you are like most PC data acquisition people these simple examples should get you started The objective here is to present how to connect common signals while avoiding discussion of electrical theory and special symbols If you need a connection we do not show or invent one please call and tell us so we can add it to this manual 5 1 CONNECTOR DIAGRAM The CIO DAS16 JR analog connector is a 37 pin D type connector accessible from the rear of the PC through the expansion backplate With the exception ofthe missing D A signals the signals availa
38. that common mode plus signal not exceed the A D board s CSR specification GROUND LOOPS Ground loops are circuits E I R created when the signal ground and the PC ground are not the same Ground loop E inducing voltage differential may be a few volts of hundreds of volts They may be constant or transient spikes differential input will prevent ground loop as long as the CSR specifications is not exceeded If ground differences greater than the CMR are encountered isolation is required WHY USE SINGLE ENDED Unanswered still is the question of why use single ended inputs First single ended inputs require fewer parts so they cost less money On an A D board the parts cost to go from 16 single ended channels to 16 differential channels ni is about 6 00 so that cannot be the reason The real reason is connector space Single ended inputs require one analog high input per channel and LLGND shared by all inputs Differential inputs require signal high and signal low inputs for each channel and one common shared LLGND 25 Single ended inputs save connector space parts cost and in all cases where there no common mode EMI RFI they work just as well as differential inputs and are less complex to wire up 7 3 LOW PASS FILTERS A low pass filter is placed on the signal wires between a signal and an A D board It stops frequencies greater than the cut off frequency from entering the A D board
39. tion is 2 1 or just 2 For a given attenuation pick a handy resistor and call it 1 R2 R2 then use this formula to calculate Digital inputs also make use of voltage dividers for example if you wish to measure a digital signal that is at 0 volts when off and 24 volts when on you cannot connect that directly to the CIO AD digital inputs The voltage must be dropped to 5 volts max when on The Attenuation is 24 5 or 4 8 Use the equation above to find an appropriate R1 if R2 is 1K Remember that a TTL input is when the input voltage is greater than 2 5 volts IMPORTANT NOTE The resistors R1 and R2 are going to dissipate all the power in the divider circuit according to the equation Current Voltage Resistance The higher the value of the resistance R1 R2 the less power dissipated by the divider circuit Here is a simple rule For Attenuation of 5 1 or less no resistor should be less than 10K For Attenuation of greater than 5 1 no resistor should be less than 1K The CIO TERMINAL has the circuitry on board to create custom voltage dividers The CIO TERMINAL is a 16 by 4 screw terminal board with two 37 pin D type connectors and 56 screw terminals 12 22 AWG Designed for table top wall or rack mounting the board provides prototype divider circuit filter circuit and pull up resistor positions which you may complete with the proper value components for your application 7 2 DIFFERENTIAL amp SINGLE END
40. ur objective here is to discover the sources of noise and discuss the means to reduce it SOURCES OF NOISE The first source of noise is the board itself Manufacturers of A D boards quote component specifications in their data sheets but rarely quote a system specification for general accuracy and noise The reasons the system is not specified are that the system specification would be less accurate than component specification and that system specifications must also specify the conditions under which the specification was made That means the PC the PC s power supply and the connection to the front end No one likes to admit it but it is true Take some very good components put them on a circuit board and place that board in a PC and the system will be less accurate than the individual components I have seen 12 bit A D boards with the same components as a DAS 16 with as little as 9 bits of accuracy due to board noise The system specification for the CIO DAS16 JR and CIO ADOS is plus or minus 1 LSB That means that if an analog input is tied to ground and the CIO DAS16 JR is on a bipolar scale the reading will be 2048 90 of the time The other 10 of the readings will be 2047 and 2049 which is count LSB This is actually not very different from the component specifications Youcan verify this by grounding an analog input channel to LLGND and taking 1000 readings then plotting ahistogram of those readings If your histogram is not
41. wing table Within each register are 8 bits which may constitute a byte of data or 8 individual bit set read functions ADDRESS READ FUNCTION WRITE FUNCTION BASE A DBits9 12158 amp Channel Set DMA INT BASE 14 CTR 2 Data A D Pacer Clock CTR 2 Data A D Pacer BASE 15 None No read back on 8254 Pacer Clock Control 8254 6 1 1 A D DATA amp CHANNEL REGISTERS BASE ADDRESS Example 300 HEX 768 Decimal 5 These four addresses Base 4 through Base 7 are the addresses used by the analog output chips on the CIO AD16 MetraByte DAS 16 In order to stay 10096 software compatible these four registers are empty on the CIO DAS16 JR Page 13 A read write register READ On read it contains two types of data The least significant 4 digits of the Analog input data and the channel number which the current data was taken from These 4 bits of analog input data must be combined with the 8 bits of analog input data in BASE 1 forming a complete 12 bit number The data is in the format 0 minus full scale 4095 FS The channel number is binary The weights are shown in the table above If the current channel were 5 then bits 4 and would be high CH8 and CH2 would be low WRITE Writing any data to the register causes an immediate A D conversion BASE ADDRESS 1 301 HEX 769 Decimal A Read only register On read the most significant A D byte is read
42. with software for calibration and test 4 1 FREQUENCY OF CALIBRATION Every board was fully tested and calibrated before being placed in finished goods inventory at the factory Your brand new CIO DASI6 JR should not require calibration before initial use For normal environments a calibration interval of 6 months to one year is recommended If frequent variations in temperature or humidity are common then recalibrate at least once every three months It takes less than 30 minutes to calibrate the CIO DASI16 JR 4 2 REQUIRED EQUIPMENT Ideally you will need a precision voltage source a calculator and some pieces of wire If you do not have a precision voltage source you will need a non precision source and have to make a few calculations You will not need an extender card to calibrate the board but you will need to have the cover off you computer with the power on so trimpots can be adjusted during calibration For that reason a plastic screwdriver has been supplied with your CIO DAS16 JR In the event that the screwdriver is dropped into the PC no damage will result from short circuits 4 3 CALIBRATING THE ANALOG INPUTS The A D is calibrated by applying a known voltage to any analog input channe and adjusting trimpots for gain amplifier input offset bipolar offset and unipolar offset There are four trimpots requiring adjustment to calibrate the analog input section of the CIO DAS16 JR The CIO DASIG R should be calibrated for the ran
43. y the CMR directly from the component data sheet ignoring the effect of the board level system on that specification A data sheet of that type might claim 10 volts of CMR Although this is a factual specification and the designer of the board or other EE would be able to translate that into systems specification most A D board owners are confused or mislead by such specs COMMON MISUNDERSTANDINGS 7 The CMR specification of a differential input is often confused with an isolation specification which it is not It makes sense doesn t it that 10 volts of CMR is the same as 10 volts of isolation No The graph above shows why Also failure to specify the common mode plus signal system specification leads people to believe that a DC offset equal to the component CMR can be rejected regardless of the input signal voltage It cannot as the graph above EUER illustrates TM Whenis adifferential input useful The best answeris whenever electromagnetic interference EMI orradio frequency interference RFI may be present in the path of the signal wires EMI and RFI can induce voltages on both signal wires and the effect on single ended inputs is generally a voltage fluctuation between signal high and signal ground A differential input is not affected in that way When the signal high and signal low of a differential input have EMI RFI voltage induced on them that common mode voltage is rejected subject to the system constraint
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