RAD242 Manual - ACCES I/O Products, Inc.
Contents
1. SERIAL COMMUNICATIONS INTERFACE Serial Port Opto isolated Matlabs type LTC485 transmitter receiver Compatible with RS 485 specification Up to 32 drivers and receivers allowed on the line I O bus address programmable from 00 to FF hex Whatever address is assigned is stored in EEPROM and used as default at next Power On Data Format Seven data bits even parity one stop bit Input Common Mode Voltage 300V minimum opto isolated If opto isolators are by passed 7V to 12V Receiver Input Sensitivity 200 mV differential input Receiver Input Impedance 12 minimum Transmitter Output Drive Capability 60 mA 100 mA short circuit current capability Serial Data Rates Programmable for 1200 2400 4800 9600 14400 19200 28800 and 57600 baud Crystal oscillator provided ENVIRONMENTAL Operating Temperature Range 0 to 65 C Optional 40 to 80 See box following for temperature de rating based on power supplied 3 2 Analog to Digital Converter Pod RAD242 User Manual The power supply voltage level that you use will affect the maximum ambient temperature that can be tolerated At higher power levels more heat will be generated by integral voltage regulators For example when 7 5 VDC is applied the temperature rise inside the enclosure is 7 3 C above the ambient temperature Thus maximum ambient temperature may have to be reduced or de rated when power supply voltages greater than 7 5 VDC are used Th2. ACCES I PRODUCTS INC 10623 Roselle Street San Diego CA 92121 1506 Tel 619 550 9559 FAX 619 550 7322 REMOTE ANALOG to DIGITAL CONVERTER MODEL 242 USER MANUAL File MRAD242 D2c Analog to Digital Converter Pod RAD242 User Manual NOTICES The information in this document is provided for reference only ACCES I O Products Inc does not assume any liability arising out of the application or use of the information or products described herein This document may contain or reference information and products protected by copyrights or patents and does not convey any license under the patent rights of ACCES nor the rights of others Printed in USA Copyright 2002 by ACCES I O Products Inc 10623 Roselle Street San Diego CA 92121 All rights reserved Analog to Digital Converter Pod RAD242 User Manual TABLE OF CONTENTS SOFTWARE rte x ease cae nee ea ee aE ew AS GENERAL shih ch dee sp sk 1 1 COMMAND DESCRIPTIONS 1 4 DIGITAL INPUT OUTPUT 1 4 ERROR CODES dtd cave 1 12 INSTALLING THE SOFTWARE kal 1 18 RAD242 INITIALIZATION dard Goa ed 1 15 HARDWARE i ac a a a ea Nea 2 1 FEATURES Sone dete Wane dete bone sede 21 DESCRIPTION lay a het ld tp
3. command received CR This occurs if the command is not recognized Error Command not fully recognized Command received CR This occurs if the first letter of the command is valid but the remaining letters are not Error Address command must be CR terminated CR This occurs if the address command xx CR has extra characters between the pod number and the CR Analog to Digital Converter Pod RAD242 User Manual INSTALLING THE SOFTWARE You have received with your product a CD that contains all the software you need to use your card The CD is compatible with any type of Windows or DOS system To install the software required for your card 1 Insert CD in your CD ROM If the install program does not start within 30 seconds run install exe from the root directory of the CD 2 Click the Install Software to Hard Disk button 3 Select the product you wish to install from the list shown 4 Click Next 5 The CD creates a directory with a default name if you want to change it click Change and select the path you prefer 6 We advise you to also install the Tools Package at least once per system Click Quick Install to run the install process or click Detailed Install if you want more information on the files installed 8 Click Finish 9 Click Exit install program when finished You now have two types of files on your hard disk 1 Software including samples in C Pascal QuickBasic and a setup program
4. 25 0 0015 of Full Scale Reading Max Tun tO Tmax 20 0075 of FSR typical Common Mode Rejection Ratio 100 dB at DC Normal Mode Rejection at 60 Hz 100 dB 0 02 min for fnorch Of 10 30 60 Hz Common Mode Rejection at 60 Hz 150 dB 0 02 min for frotcy Of 10 30 60 Hz ANALOG OUTPUTS Compensation Current 20 nom Constant current source for thermocouple cold junction reference measurements DIGITAL INPUTS Number Twelve on same pins as the output bits each bit is individually programmable as either an input or output bit Sample Rate Ports must be polled to read data Logic Input Low 0 5V to 0 8V Protected to 140 VDC 3 1 Analog to Digital Converter Pod RAD242 User Manual Logic Input High 2 0V to 50 0V Protected to 200 VDC Low Level Input Current 450 A maximum DIGITAL OUTPUTS Number Twelve on same pins as the input bits each bit is individually programmable as either an input or output bit Logic Low Output Current 350 mA maximum See box below Inductive suppression diode included in each circuit Maximum allowable current per output bit is 350 mA but for each eight bit group there is a maximum cumulative total of 650 mA Output groups are bits 0 7 and 8 11 decimal High Level Output Voltage Open collector compliance with up to 50V user supplied voltage If no user supplied voltage outputs pulled up to 5VDC via 10 K resistors
5. Authorization RMA number which must appear on the outer label of the return package All units components should be properly packed for handling and returned freight prepaid to the ACCES designated Service Center and will be returned to the customer s user s site freight prepaid and invoiced COVERAGE First Three Years Returned unit part will be repaired and or replaced at ACCES option with no charge for labor or parts not excluded by warranty Warranty commences with equipment shipment Following Years Throughout your equipment s lifetime ACCES stands ready to provide on site or in plant service at reasonable rates similar to those of other manufacturers in the industry EQUIPMENT NOT MANUFACTURED BY ACCES Equipment provided but not manufactured by ACCES is warranted and will be repaired according to the terms and conditions of the respective equipment manufacturer s warranty GENERAL Under this Warranty liability of ACCES is limited to replacing repairing or issuing credit at ACCES discretion for any products which are proved to be defective during the warranty period In no case is ACCES liable for consequential or special damage arising from use or misuse of our product The customer is responsible for all charges caused by modifications or additions to ACCES equipment not approved in writing by ACCES or if in ACCES opinion the equipment has been subjected to abnormal use Abnormal use for purposes of this warranty is def
6. Output Analog Input 0 Analog Ground Analog Input 1 Analog Ground Analog Ground 1 Use of the User Programmable Inputs require customizing the RAD242 with the RAD Firmware Development Kit available separately 3 4 Analog to Digital Converter Pod RAD242 User Manual To ensure that there is minimum susceptibility to EMI and minimum radiation it is important that there be a positive chassis ground Also proper EMI cabling techniques cable shield connect to chassis ground at the aperture twisted pair wires and in extreme cases ferrite level EMI protection must be used CE marked versions of RAD242 meet the requirements of EN50081 1 1992 Emissions EN50082 1 1992 Immunity EN60590 1992 Safety 3 5 Analog to Digital Converter Pod RAD242 User Manual WARRANTY Prior to shipment ACCES products are thoroughly inspected and tested to applicable specifications However should equipment failure occur ACCES assures its customers that prompt service and support will be available All equipment originally manufactured by ACCES which is found to be defective will be repaired or replaced subject to the following considerations TERMS AND CONDITIONS If a unit is suspected of failure contact ACCES Customer Service department prepared to give the model number serial number and a description of the failure symptom s We may suggest some simple tests to confirm the failure We will assign a Return Material
7. a 2 1 BLOCK DIAGRAM ee adaceranedaeda SEES 2 7 INSTALLING THE HARDWARE 2 8 a 3 1 INPUT OUTPUT PIN CONNECTIONS 3 5 4 1 APPLICATION CONSIDERATIONS 2 an eae aig are 1 INTRODUCTION pene 1 BALANCED DIFFERENTIAL SIGNALS 1 RS 485 DATA TRANSMISSION A 2 Analog to Digital Converter Pod RAD242 User Manual SOFTWARE GENERAL The RAD242 comes with ASCll based software provided on ASCII programming permits you to write applications in any high level language that supports text string functions allowing the REMOTE ACCES series modules to be used with virtually any computer that has a RS 485 port The communication protocol has two forms addressed and non addressed Non addressed protocol is used when only one RAD242 is in use If more than one RAD242 is in use or if any other REMOTE ACCES Pod are in use you must use the addressed protocol The difference is that an address command is sent to enable the specific pod The address command is only sent once during communication between the pod and the host computer It enables communication wi
8. analog section contains the input filters the external 5 V reference the analog to digital converter and the crystal There are three jumpers JP5 JP6 and JP7 which are used to select polarity range and bias The analog to digital converter has two differential input channels Channel 1 is used to measure the input signal while Channel 2 can be configured to be identical to Channel 1 or configured to measure the 7 5 VDC excitation voltage Vexc Digital Section The digital section consists of digital input buffers digital output latches with their associated high current open collector sinks and pull up resistors Power Supply Section The power supply section consists of power regulators that supply regulated voltages for the digital and analog circuits sensor excitation and an isolated voltage for the RS485 serial communications circuit The internal voltages are 5 VDC digital supply 5 5 VDC analog supplies 7 5 VDC sensor excitation and 5 VDC isolation power Delta Sigma Converter Model RAD242 uses a Delta Sigma analog to digital converter with on chip digital filtering providing a complete analog front end for low frequency measurement applications Delta Sigmaconverters contain charge balancing ADC a calibration microcontroller with an on chip static RAM a clock oscillator and a digital filter 2 2 Analog to Digital Converter Pod RAD242 User Manual Basic Theory of Operation The input signal to the sel
9. bandwidth is 7 86 Hz but the desired update rate is 100 Hz the data could be taken at the 100Hz rate giving a 3 dB bandwidth of 26 2 Hz Post filtering can be applied to this to reduce the bandwidth and output noise to the 7 86 Hz bandwidth level while maintaining an output rate of 100 Hz Post filtering can also be used to reduce the output noise from the device for bandwidths below 2 62 Hz At a gain of 128 the output RMS noise is 420 nV This is essentially device noise or white noise and since the converter uses a chopper stabilized input stage to reduce input drift the noise has a flat frequency response By reducing the bandwidth below 2 62 Hz the noise in the resultant passband can be reduced A reduction in bandwidth by a factor of two results in a reduction in the output rms noise This additional filtering will also result in a longer settling time The worst case settling time of the filter to a full scale step input change is 4x the data rate For example with the first filter notch at 50 Hz the full scale step settling time of the filter would be 80 ms maximum Due to a digital signal processing method used by the sigma delta converter in the RAD242 changing the channel gain in addition to the output sample rate impacts the resolution In the following table the effective resolution is defined as the magnitude of the output rms noise with respect to the input full scale i e 2x Va Gain for a of 2 5V 2 4
10. bit to 32 bit is simplified because of the similarity between VBACCES and 532 1 14 Analog to Digital Converter Pod RAD242 User Manual In the WIN32IRQ directory you have utility software to handle IRQs from any card under Win95 98 or NT 1 Drivers src with 3 subdirectories a DLL Samples for using ACCES32 DLL are provided in this directory Using this DLL not only makes the hardware programming easier MUCH easier but also one source file can be used for both Windows 95 98 and WindowsNT One executable can run under both operating systems and still have full access to the hardware registers The DLL is used exactly like any other DLL so it is compatible with any language capable of using 32 bit DLLs Consult the manuals provided with your language s compiler for information on using DLLs in your specific environment b SYS The samples in this directory are provided ONLY for WindowsNT The DevicelOControl based interaction with the register level driver is only available in NT If your code is written to use this method it will not work with Windows 95 or Windows 98 The SYS file is the actual workhorse behind hardware access in WindowsNT It utilizes the DevicelOControl function for interaction with user code Samples are provided demonstrating this API call but it is strongly recommended that the DLL interface be used The DLL described above encapsulates the SYS file and performs the DevicelOControl calls at a
11. commands other than a new address select will be executed by the selected pod The addressed mode is required when using more than one pod on the same serial bus Non Addressed Mode When there s only one pod connected no address select command is needed You can merely issue commands listed in the following table Terminology used is as follows a The single lower case letter x designates any valid hex digit 0 The single lower case letter b designates either a 1 or 0 The symbol designates either a ora d All commands are terminated with CR the ASCII character 13 e ALL information is case sensitive The symbol means zero or more valid characters total msg length lt 255 decimal 1 2 Analog to Digital Converter Pod RAD242 User Manual General Notes ALL numbers passed to and from the Pod are in hexadecimal COMMAND LIST IXx Address select command Selects the pod at address CR for communication Sets the number of times to read channel 0 before reading CR channel 1 If set to 0 it will only read Channel 0 Returns the current channel ratio loaded in the AD7710 xx CR via the serial port CR Writes the control value to the AD7710 Please refer to the CR CONTROL xxx_ control word description below for a definition of possible XXX values Used infrequently during initial setup only Stored in Flash memory on the AD7710 fo
12. frequency many times that of the analog signal sampling frequency This is called oversampling The sigma delta converter samples the input signal at a frequency of 19 5 Khz or greater dependent on the required gain to reduce the noise by spreading the noise energy of each sample over the entire measurement period resulting in ahigh accuracy low noise measurement from the 1 bit A D converter This architecture is inherently monotonic there is an output number for any analog input and provides very high accuracy but at the expense of measurement speed or data output rate To achieve 22 bits of accuracy at a 10MHz clock frequency resulting a data or measurement rate of less than 10Hz The output of the comparator provides the digital input for the 1 bit DAC allowing the system to function as a negative feedback loop that minimizes the difference signal The digital data that represents the analog input voltage is contained in the duty cycle of the pulse train appearing at the output of the comparator and can be retrieved as a parallel binary data word using a digital filter The second order sigma delta modulator and a digital filter provides a rolling average of the sampled output After power up or if there is a step change in the input voltage there is a settling time that must elapse before valid data is obtained In most signal processing and analysis applications this lag is insignificant However in real time control applications this lag
13. should be carefully considered and analyzed 2 3 Analog to Digital Converter RAD242 User Manual Programmable Digital Filter The internal digital filter removes noise added during the conversion and sums the oversampled readings to produce multiple bit measurements at a data update rate determined by the first notch of the digital filter Internally the converter provides measurements at a 19 5 KHz output rate and is filtered down to the update rate defined by the digital filter The cutoff frequency of the digital filter is determined by the value loaded to bits FSO to FS11 in the control register At the maximum clock frequency of 10 MHz the minimum cutoff frequency of the filter is 2 58 Hz while the maximum programmable cutoff frequency is 269 Hz Since the ADC contains the on chip low pass filtering there is a settling time associated with step function inputs Data on the output will be invalid after a step change until the settling time has elapsed The settling time depends on the notch frequency chosen for the filter The output data rate equates to the filter notch frequency and the settling time of the filter to a full scale step input that is four times the output data period In applications using both input channels the settling time of the filter must be allowed to elapse before data from the second channel is accessed Post filtering may be used to increase the update rate or reduce the output noise For example if the
14. small penalty in speed A call through the DLL interface c VXD source fo the driver 2 Samples Samples in VisualC Delphi and C Builder RAD242 INITIALIZATION 1 Run the setup program from the directory that the software was installed Use the menus to set jumper J5 Vret internal 2 5V or external 5V jumper J6 polarity unipolar bipolar and jumper J7 bias 2 5V or ground depending on selected range and polarity 2 Apply power to the card connected to the serial bus 3 Setup the gain word length channel number range and polarity for the card by programming the control register bits 20 12 Review the Control Register Programming Section starting on page 3 9 of this manual Set the digital notch filter frequency by writing a bit pattern into bits 11 0 of the control register 4 The setup program creates batch file called RISC BAT Run this program to run RISCTERM using the CONTROL command in RISCTERM Analog to Digital Converter Pod RAD242 User Manual 5 Perform the calibration routine for Channel 1 see paraaragraph Calibration in Chapter 2 of the manual 6 Perform the calibration routine for Channel 2 Analog to Digital Converter Pod RAD242 User Manual HARDWARE FEATURES Remote Intelligent Analog Digital I O Unit with Opto lsolated RS 485 Interface to Host Computer Higher Baud Rates and Simpler Programming Than Competitor Units NEMA 4 Enclosure for Harsh Atmospheric and Marin
15. the ISL position If you wish to by pass the opto isolators then you can move these jumpers to the ISL position 2 8 Analog to Digital Converter Pod RAD242 User Manual There are three jumpers on the analog to digital card Their functions are as follows JP5 is used to select bias 2 5 V or ground JP6 is used to select the internal 2 5 VDC reference or an external 5VDC reference If the internal reference is selected then the input voltage range is 0 2 5V or 2 5V If the external 5VDC reference is selected then the input voltage range is 0 5V or 5V JP7 is used to select either Unipolar or Bipolar mode of operation 2 9 Analog to Digital Converter Pod RAD242 User Manual SPECIFICATIONS ANALOG INPUT Channels 2 Differential Data Coding Binary for Unipolar inputs Offset Binary for Bipolar inputs Resolution Dependent on filter frequency See Table 1 Input Voltage Range Jumper selectable 0 2 5V 0 5V 2 5V 5V Input Impedance Varies with input sample rate 250G Programmable Gains 1 2 4 8 16 32 64 and 128 Overvoltage Continuous single channel to 35 V without damage DC Input Leakage Current 25 C 10 pA max Temp Coefficients Note Recalibration at any temperature or background calibration will remove drift errors Due to the thermal insulation of the NEMA enclosure and internal heating of the power supply regulators the actual coefficients are lowered Integral Nonlinearity
16. Analog to Digital Converter Pod RAD242 User Manual Table 1 Effective Resolution vs Gain and Output Data Rate Effective Resolution Bits 3dB a al Fl eal Ee of 1 of 2 of 4 of 8 of 16 of 32 of 64 of 128 rom enere ers ars as aos ros res 1s este osef o es s 20 20 vs v5 ves 05 163 Calibration Despite the use of inherently stable sigma delta converters with low drift and noise immune components occasional calibration is required Calibration removes the errors due to the effects of temperature drift supply sensitivity time drift on zero and full scale gain errors from the device A calibration routine is required on the devices whenever there is a known change in the ambient operating temperature or supply voltage It should also be done if there is a change in the selected channel gain filter notch or bipolar unipolar input range Power up and Calibration Upon application of system power the analog to digital converter performs an internal reset which sets the bits in the control register to a known state The RAD242 has four types of calibration self calibration background calibration system calibration and system offset calibration The setup of control register bits 23 21 MD2 MD1 amp MDO determines the operational and calibration modes See Chapter 3 of this manual for detailed programming of the control register Information on the calibration mod
17. D 00 RECEIVE Pod 00 CR Enter a New Program PROGRAM This command initiates transfer of a new program to the RAD242 1 11 Analog to Digital Converter Pod RAD242 User Manual This command should be used carefully If you accidentally issue a PROGRAMSs command ESC ASCII 27 will restart the pod as if power had been reset This feature is designed to allow ACCES to provide field upgrades to the RAD242 firmware and for advanced users the opportunity to customize the firmware in the pod Documentation relating to use of this command is provided with the upgrade CD or is available separately for a small fee Vertical Same the PROGRAM command except it is used only after a reset has occured Allows access to POD to download new firmware ERROR CODES The following error codes can be returned from the pod 1 Invalid channel number too large or not a number All channel numbers must be between 00 and 17 in hex 0 24 decimal 3 Improper Syntax Not enough parameters is the usual culprit 4 Channel number is invalid for this task For example if you try to output to a bit that is set as an input bit that will cause this error 9 Parity error This occurs when some part of the received data contains a parity or framing error Additionally several full text error codes are returned All begin with Error and are useful when using a terminal to program the pod Error Unrecognized Command
18. Examples Write zeros to bits 0 7 and ones to 8 11 SEND RECEIVE CR CONTROL REGISTER PROGRAMMING The A D chip contains a 24 bit control register accessible using the CONTROL xxxxxx and CONTROL commands These commands write and read the control register s value The following table shows the bits comprising the control register Writing the 6 digit hex number which contains the correct bit pattern for the control function you wish to perform will set and clear the bits in the A D chip It is important to write at least one CONTROL xxxxxx value for each channel you are going to acquire This will configure the range corner frequency and other options for the channel you specify For most applications set the MD2 0 bits to 000 or before you start taking data set the bits to 001 one time per channel to do a quick self calibration The PD bit should be left O Setting this bit to 1 will prevent the pod from acquiring data as it forces the A D into low power mode 23 22 21 20 19 18 17 16 15 14 13 12 wor woo er Joo p gt m eo au 11 10 09 08 07 06 05 04 03 02 01 00 2 0 Operations Mode Bit Selection Options Operating Mode Description Normal Mode This is the normal mode of operation of the device This is the default condition of these bits after initial power on reset Active Self Calibration This activates self calibration on the channel select
19. PortB InPort and OutPort to access the hardware This directory also contains the device driver for NT This device driver provides register level hardware access from Windows NT normally called through ACCES32 DLL Two methods of using the driver are provided the ACCES32 DLL recommended and the DevicelOControl handles direct to the SYS file slightly faster ACCES95 and ACCESNT These two drivers are mentioned for users migrating from older versions of ACCES Tools The functionality of ACCES95 and ACCESNT has been combined into ACCES32 DLL which is described up In order to modify your software to use the new ACCES32 DLL change the file you link to from ACCES95 or ACCESNT to ACCES32 No other changes are necessary If you want to avoid recompiling software that was written for ACCES95 ACCESNT just rename ACCES32 DLL to the appropriate name 95 or NT Inthe BSAMPLES directory A Quickbasic sample In the CSAMPLES directory Samples in C In the directory This directory contains PCl bus specific programs and information If you are not using an ACCES PCI card you can ignore or delete this directory In the PSAMPLES directory This directory contains samples in Pascal In the VBACCES directory Sixteen bit DLL drivers for use with VisualBASIC 3 0 and Windows 3 1 only These drivers provide four functions similar to the ACCES32 DLL However this DLL is only compatible with 16 bit executables Migration from 16
20. S 232 devices is that a balanced differential drive method is used Ina balanced differential system the voltage produced by the driver appears across a pair of wires A balanced line driver will produce a differential voltage from 2 to 6 volts across its output terminals A balanced line driver can also have an input enable signal that connects the driver to its output terminals If the enable signal is OFF the driver is disconnected from the transmission line This disconnected or disabled condition is usually referred to as the tristate condition and represents a high impedance RS 485 drivers must have this control capability RS 422 drivers may have this control but it is not always required A balanced differential line receiver senses the voltage state of the transmission line across the two signal input lines If the differential input voltage is greater than 200 mV the receiver will provide a specific logic state on its output If the differential voltage input is less than 200 mV the receiver will provide the opposite logic state on its output A maximum operating voltage range is from 6V to 6V allows for voltage attenuation that can occur on long transmission cables A 1 Analog to Digital Converter Pod RAD242 User Manual A maximum common mode voltage rating of 7V provides good noise immunity from voltages induced on the twisted pair lines The signal ground line connection is necessary in order to keep the com
21. S LATCHES ISOLATED OWER IN OWER SUPPLY OPTIONAL EXPANSION Le k 10 VDC PRECISION POWER REGULATOR INPUT The built in watchdog timer resets the pod if for some unexpected reason microcontroller hangs up or the power supply voltage drops below 4 75 VDC Data collected by the pod can be stored in local RAM and accessed later through the computer s serial port This allows the pod to operate in a stand alone pod mode Analog to Digital Converter Pod RAD242 User Manual INSTALLING THE HARDWARE The RAD242 enclosure is an easily mounted NEMA 4 compliant unit Outside dimensions of the enclosure are 4 53 by 3 54 by 2 17 high Input output wiring is sealed by a gland assembly The cover is secured to the body by four recessed M 4 stainless steel captive screws Two long M 3 5 x 0 236 screws are provided for mounting the body Mounting holes and cover attaching screws are outside the sealed area to prevent ingress of moisture and dust Four threaded bosses inside the enclosure provide for mounting the printed circuit card assemblies Power and Communications Wiring Electrical power and RS 485 connections to the pod are made internal to the pod on a removable termination board that plugs into the personality module of the RAD unit ISO GND and ISO PWR This is the power connection for the isolated section which may be supplied from the computer s 12
22. VDC supply an extra pair of wires on the RS 485 network or froma central power supply To maintain isolation this power must be independent of local power The voltage level can be from 7 5 VDC to 23 VDC An on board voltage regulator regulates the power to 5 VDC RAD242 will require only about 40 mA of current and thus any voltage drop of computer power will be inconsequential If separate power is not available then with some loss of isolation these terminals can be jumpered to the local power terminals RS485 These are the differential transmit and receive lines for two wire communications EXV This terminal is for the external voltage level to the inductive suppression diodes included with the digital outputs EXV can be as high as 50 VDC PWR GND These terminals are used to apply 12 VDC power to the pod froma local power supply The voltage can be anywhere in the range from 10 5 VDC to 18 VDC Higher voltage can be used 24 VDC for example if an external zener diode is used to reduce the voltage applied to the RAD242 See the Specification section of this manual to determine the zener diode power rating required Jumpers There are four jumper locations on the CPU small card Their functions are as follows JP1 adjacent to U22 This jumper will be in the 32K position and need not concern you JP2 adjacent to U19 JP3 and JP4 adjacent to U16 Normally these jumpers should be in
23. d a watchdog timer circuit gives RAD242 the capability and versatility expected from a modern distributed control system To accommodate special programs the EEPROM can be expanded to 32x8K RAD242 contains CMOS low power circuitry an optically isolated receiver transmitter and power conditioners for local and external isolated power It can operate at baud rates up to 57 6 Kbaud and distances up to 4000 feet with low attenuation twisted pair cabling All programming of RAD242 is in ASCll based software ASCll based programming permits you to write applications in any high level language that supports ASCII string functions and you can use ACCES R series pods with virtually any computer 2 1 Analog to Digital Converter Pod RAD242 User Manual The module or pod address is programmable from 00 to FF hex and whatever address is assigned is stored in EEPROM and used as the default address at the next Power ON Similarly the baud rate is programmable for 1200 2400 4800 9600 14400 19200 28800 and 57600 The baud rate is stored in EEPROM and used as default at the next Power ON The personality board has mounted on it the interface connector J1 and two 20 pin connectors P2 and J3 for mating to the microcontroller board connectors J2 The personality board consists of three sections 1 Analog section 2 Digital section 3 Power supply section The layout of each section is discussed below Analog Section The
24. de is on then the AD7710 provides continuous self calibration of the reference and shorted zeroed inputs The calibration takes place as part of the conversion sequence extending the conversion time and reducing the word rate by a factor of six Its major advantage is that the user does not have to worry about recalibrating the device when there is a change in the ambient temperature In this mode the shorted zeroed inputs and VREF as well as the analog input voltage are continuously monitored and the calibration registers of the device are automatically updated Full Scale Calibration Coefficients This is accessed using 1 Re Csn xxxxxx command 1 Default condition after internal power on Channel Selection Bit Patterns Channel CH Control Register Bit 17 Channel Selected ptt De aut condition after POR Analog to Digital Converter Pod RAD242 User Manual pin Power Down Selection Bit Patterns Power Down PD Control Register Bit 16 Power Status of AD7710 Chip Word Length Selection Bit Patterns Word Length WL Control Register Bit 15 Output Word Length 24 Bit Output Compensation Current Selection Bit Patterns Current Output IO Control Register Bit 14 Output Compensation Current 0 Defaut condition after POR Break Detect Current Selection Bit Patterns Burn Out Current BO Control Register Bit 13 Device Break Current OF Defaut Condition After POR Bi
25. e Environments 8031 Microcontroller with 32K x 8 bits RAM and 8K x 8 bits EEPROM 32k x 8 bits optional 2 Channel 24 Bit Analog Digital Delta Sigma Converter Bi polar and Unipolar Voltage Input Ranges of 2 5 V and 5 V Self Calibrating or Auto Calibrating Modes to Eliminate Drift Errors 12 Bit Digital Port with Each Bit Programmable as Either Input or Output Constant Current Source for Thermocouple Cold Junction Compensation All Programming in Software few jumpers DESCRIPTION Model RAD242 is an intelligent two channel 24 Bit analog input interface unit It is packaged in a NEMA4 enclosure for remote installation in harsh environments Communication with the host computer is EIA RS 485 half duplex serial communications protocol ASCll based protocol permits communication with virtually any computer system that has an Asynchronous RS 485 port RAD242 is one of a series of remote intelligent pods called the REMOTE ACCES Series As many as 32 REMOTE ACCES Series pods may be connected on a single two wire multi drop RS 485 network Each unit has a unique address Communication uses a master slave protocol wherein the pod talks only if questioned by the computer The enclosure contains three boards 1 The microcontroller board 2 Personality board 3 Termination board The microcontroller board s type 8031 microcontroller with 32x8K RAM 8x8K non volatile EEPROM an
26. e equation to determine temperature de rating is Viqy_ 129 lt 22 Ta in C 7 where is the ambient temperature and 12 is the input voltage at which the voltage regulator junction temperature will rise to the maximum rated temperature of 120 For example at an ambient temperature of 25 the voltage V can be up to 18 4V Atan ambient temperature of 100 F 37 8 C the voltage V can be up to 16 6V Storage Temperature Range 50 C to 120 C Humidity 5 to 95 RH non condensing Enclosure is designed to meet NEMA4 requirements Size NEMA4 enclosure 4 53 long by 3 54 wide by 2 17 high 115 mm Long x 90 mm Wide x 55 mm High POWER Power for the opto isolated section can be applied from the computer s 12 DC power supply via the serial communications cable and from a local power supply for the rest of the unit Opto lsolated Section 7 5 to 23 VDC 40 mA Note Due to the small amount of current required voltage drop in the communication cable is of no significant consequence Local Power 10 5 to 16VDC at 150 mA See box that follows 10 5 to 16VDC at 50 mA If the local power supply has an output voltage greater than 16VDC you can install a Zener diode in series with the supply voltage The voltage rating of the Zener diode should be equal to V 16 where V is the power supply voltage The power rating of the Zener diode should be V x 0 15 W Thus for example a24VDC power s
27. ected analog input channel is continuously sampled at a rate determined by the frequency of the master clock and the selected gain A charge balancing A D converter Sigma Delta Modulator converts the sampled signal into a digital pulse train whose duty cycle contains the digital information The programmable gain function on the analog input is also incorporated in the modulator with the input sampling frequency being changed to provide higher gains A digital low pass filter processes the output of the modulator and updates the output register at a rate that is determined by the first notch frequency of the low pass filter The output data can be read from the serial port randomly or periodically at any rate up to the output register update rate The first notch of this digital filter can be programmed via an on chip control register The programmable range for this first notch frequency is from 9 76 Hz to 1 028 Khz giving a programmable range for the 3 db frequency of 2 58 Hz to 269 Hz Detailed Theory of Operation The sigma delta ADC contains the following elements A sample hold amplifier A differential amplifier or subtractor An analog low pass filter A 1 bit A D converter comparator A 1 bit DAC A digital low pass filter SD Ye The analog signal sample is fed to the subtractor along with the output of the 1 bit DAC The filtered difference signal is then fed to the comparator whose output then samples the difference signal at a
28. ed by CH Bit 17 of the control register This is a one step calibration sequence and when complete the part returns to the normal mode 2 0 000 For this calibration type the zero scale calibration is done internally on shorted zero inputs and the full scale calibration is done internally on VREF 1 6 nalog to Digital Converter Pod RAD242 User Manual Activate System Calibration This activates system calibration on the channel selected by CH Bit 17 of the Control Register This is a two step calibration sequence with the zero scale calibration done first on the selected input channel The part returns to normal mode 2 000 at the end of this first step in the two step sequence Activate System Calibration This is the second step of the system calibration sequence with the full scale calibration being performed on the selected input channel When this calibration is complete the part returns to the normal mode Activate System Offset Calibration This activates system offset calibration on the channel selected by CH This is a one step calibration sequence and when complete the part returns to the normal mode For this calibration type the zero scale calibration is done on the selected input channel and the full scale calibration is done internally on VREF Active Background Calibration This activates background calibration on the channel selected by CH If the background calibration mo
29. es follows In the self calibration mode the zero scale point used in determining the calibration coefficient is done with both inputs being shorted internally The full scale coefficient is determined by the span between the shorted inputs conversion and the conversion on the internal reference node Vref System calibration allows the analog to digital converter to compensate for system gain and offset errors as well as its own internal errors System calibration uses voltage values presented by the system to the analog input for the zero and full scale points This is a two step procedure The first step requires application of the zero voltage calibration 2 5 Analog to Digital Converter Pod RAD242 User Manual register bits MD2 MD1 amp MDO will have a 0 1 0 written to them Inthe second step the full scale point is applied to both inputs The second step is then initiated by writing a 0 1 1 to control register bits MD2 MD1 amp MDO respectively The applied input voltages must be stable during each step of the calibration procedure In the system offset calibration the zero scale point is determined by the conversion of the zero voltage presented to the input of the converter analog input The full scale coefficient is determined from the span between the analog input conversion and a conversion of the Vref This is a single step approach and starts with setting the control register bits MD2 MD1 and MDO with the value 1 0 0 I
30. he message is sent in the old baud rate not the new one Once the message is transmitted the pod changes to the new baud rate The new baud rate is stored in EEPROM and will be used even after power reset until the next BAUD xxx command is issued 1 9 Analog to Digital Converter Pod RAD242 User Manual Example Set the pod to 19200 baud SEND BAUD 555 RECEIVE Baud 05 CR Set the pod to 9600 baud SEND BAUD 333 RECEIVE Baud 03 CR Read Firmware Revision Number Read the firmware revision number Reads the version of firmware installed the pod It returns X XX CR Example Read the RAD242 version number SEND V RECEIVE 1 00 CR NOTE The command returns the version number along with other information Resend Last Response n Resend last response This command will cause the pod to return the same thing it just sent This command works for all responses less than 255 characters in length Normally this command is used if the host detected a parity or other line fault while receiving data and needs the data to be sent a second time The command may be repeated Example Assuming the last command was l ask pod to resend last response SEND n RECEIVE FFF CR whatever the data was Hello Message H Hello message Any string of characters starting with will be interpreted as this command H CR alone is also acceptable The return from this command ta
31. ined as any use to which the equipment is exposed other than that use specified or intended as evidenced by purchase or sales representation Other than the above no other warranty expressed or implied shall apply to any and all such equipment sold or furnished by ACCES 4 1 Analog to Digital Converter Pod RAD242 User Manual APPENDIX A APPLICATION CONSIDERATIONS INTRODUCTION Working with RS 422 and RS 485 devices is not much different from working with standard RS 232 serial devices and these two standards overcome deficiencies in the RS 232 standard First the cable length between two RS 232 devices must be short less than 50 feet at 9600 baud Second many RS 232 errors are the result of noise induced on the cables The RS 422 standard permits cable lengths up to 5000 feet and because it operates in the differential mode it is more immune to induced noise Connections between two RS 422 devices with CTS ignored should be as follows 7 7 A third deficiency of RS 232 is that more than two devices cannot share the same cable This is also true for RS 422 but RS 485 offers all the benefits of RS 422 plus allows up to 32 devices to share the same twisted pairs An exception to the foregoing is that multiple RS 422 devices can share a single cable if only one will talk and the others will all receive BALANCED DIFFERENTIAL SIGNALS The reason that RS 422 and RS 485 devices can drive longer lines with more noise immunity than R
32. is at 1 Khz a new word is available every 1 mSec The settling time of the filter to full scale step input change is worst case 4 x 1 output data rate This settling time is to 100 of the final value For example with the first notch filter at 50 Hz the settling time of the filter to full scale step input change is 80 mSec maximum If the first notch is at 1 Khz the settling time of the filter to a full scale input step is 4 msec maximum This settling time can be reduced to 3 x 1 output data rate by synchronizing the step input change to a reset of the digital filter In other words if the step input time takes place with SYNC low the settling time will be x 1 output data rate If a change of channels takes place the settling time is 3 x 1 output data rate regardless of the SYNC input The 3 db frequency is determined by the programmed first notch frequency according to the relationship filter 3 db frequency 0 262 x first notch frequency Set a New Baud Rate When shipped by ACCES the baud rate is set at 9600 BAUD xxx Program the pod with a new baud rate This command sets the pod to communicate at a new baud rate The parameter passed Xxx is slightly unusual Each x is the same digit from the following table 9 600 14 400 19 200 28 800 57 600 Therefore valid values for the command s 000 111 222 333 444 555 666 777 The pod returns a message indicating it will comply T
33. istate condition The following illustration shows a typical multidrop or party line network Note that the transmission line is terminated on both ends of the line but not at drop points in the middle of the line A 2 Analog to Digital Converter Pod RAD242 User Manual TERMINATION RESISTORS AT BOTH ENDS ONLY TX ENABLE RX ENABLE Typical RS 485 Two Wire Multidrop Network A 3
34. kes the form without the quotes Analog to Digital Converter Pod RAD242 User Manual Pod aa RAD242 Rev rr Firmware Ver x xx ACCES I O Products Inc 15 the pod address rr is the hardware revision such as B1 x xx is the software revision such as 1 00 Example Read the greeting message SEND Hello RECEIVE Pod 00 RAD242 Rev B1 Firmware Ver 1 00 ACCES I O Products Program the Pod Address POD xx Program the currently selected pod to respond at address xx This command changes the pod s address to xx If the new address is 00 the pod will be placed into non addressed mode If the new address is not 00 the pod will not respond to further communications until a valid address command is issued Hex numbers 00 FF are considered valid addresses The R specification allows only 32 drops on the line so some addresses may be unused The new pod address is saved in EEPROM and will be used even after power down until the next POD xx command is issued Note that it the new address is not 00 i e the pod is configured to be in addressed mode it is necessary to issue an address command to the pod at the new address before it will respond The pod returns a message containing the pod number as confirmation Example Set the pod address to 01 SEND POD 01 RECEIVE Pod 01 CR Set the pod address to SEND POD F3 RECEIVE Pod F3 CR Take the pod out of addressed mode SEND PO
35. ly returned as an equals sign and 6 hexadecimal digits xxxxxx If 16 bit data Word Length has been selected with the WL bit in the CONTROL function the least two significant digits 8 bits will always report FF If the sample returned has already been read the equals sign will instead be a slash The channel specified in the parameter is acquired using the polarity gain specified and corner frequency that was configured using the CONTROL command Channel Sample Ratio Control CSR xx Sets the channel sample ratio to xx CSR Read back the channel sample ratio With the channel sample ratio set to zero the pod will not read channel 1 at all With any other value the pod will take a number of samples from channel 0 equal to the CSR before each sample taken from channel 1 Due to the nature of Sigma Delta A D convertions a number of samples are thrown away by the pod each time it changes channels For this reason optimizing channel selection via the CSR command is recommended DIGITAL INPUT OUTPUT Configure Bits as Input or Output 1 4 Analog to Digital Converter Pod RAD242 User Manual Configure digital bits as input or output This function programs on a bit by bit basis the digital bits as input or output A zero in any bit position of the xxxx control byte designates the corresponding bit as an input Conversely a one designates a bit to be configured a
36. mon mode voltage within that range The circuit may operate without the ground connection but may not be reliable RS 422 Specification Summary Driver Output Voltage unloaded Driver Output Voltage loaded L and LDGND jumpers in Driver Output Resistance 50 Driver Output Short Circuit Current 150 mA Driver Output Rise Time 10 unit interval Receiver Sensitivity 200 mV Receiver Common Mode Voltage 7V Range 4K Receiver Input Resistance To prevent signal reflections in the cable and to improve noise rejection in both the RS 422 and RS 485 mode the receiver end of the cable should be terminated with a resistance equal to the characteristic impedance of the cable An exception to this is the case where the line is driven by an RS 422 driver that is never tri stated or disconnected from the line In this case the driver provides a low internal impedance that terminates the line at that end RS 485 DATA TRANSMISSION The RS 485 Standard allows a balanced transmission line to be shared in a party line mode As many as 32 driver receiver pairs can share a two wire party line network Many characteristics of the drivers and receivers are the same as in the RS 422 Standard One difference is that the common mode voltage limit is extended and is 12V to 7V Since any driver can be disconnected or tri stated from the line it must withstand this common mode voltage range while in the tr
37. n the background calibration mode the self calibration procedure interleaves with the normal conversion sequence In this mode the data conversion rate of the analog to digital converter is reduced by a factor of six The recommended calibration modes are system offset calibration and system calibration The user will determine the best method dependent on the operating circumstances However it is necessary to perform the calibration routine after power up and after reaching thermal equilibrium inside the enclosure and when the gain range and polar bipolar mode are changed Digital Inputs Outputs In addition to the analog input channels RAD242 has 12 bits of bi directional digital input output bits The outputs have high current sinking capacity 350 mA and their open collector outputs can be connected to a external voltage sources of up to 50 VDC If no external source is used then each I O bit is pulled up to 5 VDC via 10 Kohm resistors The inputs can withstand voltages from 140 VDC to 200 VDC Applications The RAD242 is intended for wide dynamic range measurement of low frequency signals Typical applications include strain gauge weight measurement precision thermocouple thermometry and chromatography With the addition of the rugged enclosure and built in intelligence the RAD242 is also suitable for process control plant monitoring HVAC monitoring and smart house applications RAD242 s design is optimized to perform reading
38. polar Unipolar Selection Bit Patterns Bipolar Unipolar B U Control Register Bit 12 Bipolar Unipolar Selection for both Inputs Filter Selection FS11 FS00 3 The on chip digital filter provides a Sin c filter response The 12 bits of data programmed into these bits determine the filter cutoff frequency the position of the first notch of the filter and the data rate for the part In association with the gain selection it also determines the output noise and hence the effective resolution of the device The first notch of the filter occurs at a frequency determined by the relationship filter first notch frequency fok In 512 copE Where code is the decimal equivalent of the code in bits FS00 to FS11 and is in the range 19 to 2000 With nominal fck in of 10 MHz this results in a first notch frequency from 9 76 Hz to 1 028 Khz To ensure correct operation of the 1 8 Analog to Digital Converter Pod RAD242 User Manual AD7710 the value of the code loaded to these bits must be within this range Failure to do this will result in unspecified operation of the device Changing the filter notch frequency as well as the selected gain impacts resolution The output data rate or effective conversion time for the device is equal to the frequency selected for the first notch of the filter For example if the first notch of the filter is selected at 50 Hz then a new word is available at a 50 Hz rate or every 20 mSec If the first notch
39. r future use A D Channel Calibration Scaling Factor CR A D Channel Calibration Offset Factor CR Read Current Scale or Offset Calibration Factor XXXXXXxX CR Czn BAUD xxx Sets the serial port communications baud rate Queries the firmware Version Number x xx CR n Asks the Pod to resend the previous response See description H Hello Command Returns pod name revision and See copyright message description Sets the pod address to xx Pod xx PROGRAM Replaces the pod s EEPROM program Reserved for factory CR use 1 3 Analog to Digital Converter Pod RAD242 User Manual COMMAND DESCRIPTIONS The following paragraphs give details of the command functions describe what the commands cause and give examples Please note that all commands have an acknowledgment response You must wait fora response from a command before sending another command Address Select xx Selects the Pod addressed xx NOTE When using more than one Pod in a system each Pod is configured with a unique address This command must be issued prior to any other commands to that particular Pod This command needs to be issued only once prior to executing anyother commands Once the address select command has been issued that Pod willrespond to all other commands until a new address select command is issued Report Most Recent Analog Data AO or A1 Returns the data from the specified channel immediately via the serial port The data is normal
40. s an output Note Any bit configured as an output can still be read as an input if the current value output is a Examples Program even bits as outputs and odd bits as inputs SEND MAAAA RECEIVE CR Program bits 0 7 as input and bits 8 F as output SEND MFFOO RECEIVE CR Read Digital Inputs Read 12 bits These commands read the digital input bits from the pod All byte or word wide responses are sent most significant nibble first Examples Read ALL 12 bits SEND RECEIVE FFFFFF CR Write Digital Outputs Oxxxx Write to all 12 digital output bits This command write outputs to digital bits Any attempt to write to a bit configured as input will fail Writing to a word wherein some bits are input and some are output will cause the output latches to change to the new value but the bits which are inputs will not output the value until unless they are placed in output mode Single bit commands will return an error 4 if an attempt is made to write to a bit configured as an input Writing a to a port asserts the pull down Writing a zero de asserts the pull down Therefore if the factory installed 5V pull up is installed writing a one will cause zero volts to be at the connector and writing a zero will cause 5 volts to be asserted If the factory installed pull up has been removed the user supplied pull up will be asserted 1 5 Analog to Digital Converter Pod RAD242 User Manual
41. s on channel 1 with occasional readings channel 2 This would be ideal for thermocouple measurements with the cold junction reference attached to channel 1 or for precision measurements of bridge sensors to monitor the excitation voltage or current 2 6 Analog to Digital Converter Pod RAD242 User Manual Broken Transducer Detection On analog channel 0 there is a switchable current source that can detect a burnt out or disconnected external sensor This current source may be used to check if the transducer is burned out or opened before attempting to take measurements on that channel If the current is turned on and is allowed to flow into the transducer then the resulting voltage can indicate if transducer is functioning properly Output Compensation Current A current source 20 uA is available Pin J1 18 to generate cold junction reference using an RTD thermistor or any other suitable method For the control register setup to use Broken Transducer Detection and Output Compensation Current see section 3 10 of the manual BLOCK DIAGRAM CURRENT r CONVERTER OUTPUT l BREAK DETECTION XTAL WATCHDOG Osc CIRCUIT 609 0 AD INPUT 0 gt ADINPUT1 gt RESET OUTPUT EXTERNAL 9081 RESET MICRO CONTROLLER DIGITAL INPUT OPTO RS485 PORT vo ISOLATORS 1 1 LATCHES SOURCE VOLTAGE ii INPUT OUTPUT OUTPUT SOP TIONAL EXPANSION 1 DRIVER
42. source code Three functions are provided initComCard writePod and readPod The functions are polling based with IRQ necessary and deal with strings rather than character by character Consult the source code files for more information SAMPLE ACCES provides a sample program that demonstrates reading inputs polling the pod for general information and the use of the driver PROGRAM EXE or WINPROG EXE Depending on the exact configuration options requested when the unit was purchased you may or may not have this file This program is used to upgrade the pod More information is provided with the program Command Structure All serial communication must be formatted as 7 data bits even parity 1 stop bit All numbers sent to or received from the pod are in hexadecimal form The factory default baud rate is 9600 Baud The pod is considered to be in addressed mode any time its pod address is changed from the factory default pod address of 00 non addressed mode Addressed Mode The address select command must precede any other command to an addressed pod The address command is as follows Ixx CR where xx is the pod address from 01 to FF hex and CR is Carriage Return ASCII character 13 The pod responds with either xxN CR or xxY CR if an input change of state has occurred on enabled bits since the last Y or address command Once the address select command has been issued all further
43. specifically for your card 2 Software to help you use ACCES cards under a variety of environments Setup exe Setup program Findbase exe DOS utility to determine an available base address for ISA bus non PnP cards Run this program once before the hardware is installed in the computer to determine an available address to give the card Once the address has been determined run the setup program provided with the hardware to see instructions on setting the address switch and various option selections Poly exe A generic utility to convert a table of data into order polynomial Useful for calculating linearization polynomial coefficients for thermocouples and other non linear sensors Risc bat A batch file demonstrating the command line parameters of RISCTerm exe Analog to Digital Converter Pod RAD242 User Manual RISCTerm exe A dumb terminal type communication program designed for RS422 485 operation Used primarily with REMOTE ACCES data acquisition Pods and our RS422 485 serial communication product line Can be used to say hello to an installed modem RISCTerm stands for Really Incredibly Simple Communications TERMinal In the ACCES32 directory This directory contains the Windows 95 98 NT driver used to provide access to the hardware registers when writing 32 bit Windows software Several samples are provided in a variety of languages to demonstrate how to use this driver The DLL provides four functions Out
44. th that specific pod and disables all other devices on the network SETUP EXE A menu driven program designed to assist you to configure your RAD242 The program instructs you on use of the serial communications opto isolation jumpers and allows you to specify the Pod Address and the serial baud rate This program can also auto detect the address and or baud rate of an attached Remote Acces Pod The Setup program also instructs you how to select converter input range polarity mode and bias using jumpers JP7 unipolar bipolar JP6 External ref 5 VDC or internal ref 2 5 VDC and JP5 bias 2 5V or ground depending on the selected polarity and range The input voltage ranges polarity and bias are interdependent as shown below The Setup program should be run with only a single pod attached to the RS 485 port in your computer You will need to Know the setup information base address IRQ of the port so that the Setup program can access it The Setup program will create a batch file in it s directory called RISC BAT that can be used to run RISCTerm RISCTerm This program provides a simple non automated interface to RS 485 devices and can be used to configure or test RAD242 setup and operations Help on using RISCTerm is provided in program and is accessed by pressing F1 key 1 1 Analog to Digital Converter Pod RAD242 User Manual DRIVERS COMMDRV PAS and COMMDRV C are communication shortcuts or drivers provided in and Pascal
45. upply would require using 8 2V Zener diode with a power rating of 8 2 0 15 1 3 3 Analog to Digital Converter Pod RAD242 User Manual INPUT OUTPUT PIN CONNECTIONS Input and output connections can be made one of two ways a at Euro style screw terminals TB1 and TB2 or b at 37 pin male sub D connector J1 37 Pin D Sub J1 Pin Connections Pin Number Signal DI O0 DI O1 01 02 DI O3 01 04 DI O5 0 06 01 07 01 08 01 09 DI O10 DI O11 PINT1 AGND ANO AN1 AGND IOUT RST RS485 RS485 PBRST ISO GND ISO PWR GND EXV GND PWR PWR PTO VEXC VEXC ANO AGND AN1 AGND AGND Description Digital Input Output Bit 0 Digital Input Output Bit 1 Digital Input Output Bit 2 Digital Input Output Bit 3 Digital Input Output Bit 4 Digital Input Output Bit 5 Digital Input Output Bit 6 Digital Input Output Bit 7 Digital Input Output Bit 8 Digital Input Output Bit 9 Digital Input Output Bit 10 1 Digital Input Output Bit 11 User Programmable Interrupt Input Analog Ground Analog Input 0 Analog Input 1 Analog Ground Current Output System Reset Acknowledge Negative when PC is Reset Positive Transmit amp Receive Negative Transmit amp Receive Processor Board Reset Ground Isolated Power Supply In Ground Digital Output Clamp Diode Voltage Input Ground Power Supply In Power Supply In User Programmable Counter Timer Input 7 5 VDC Bridge Excitation Output 7 5 VDC Bridge Excitation
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