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Chapter 2

Converting a Twos Complement Code to a Voltage

To convert a twos complement code into a voltage, use the following
formulas:

LSB = FSR

Code

Offset Binary

= Code

Twos Complement

XOR 2

N-1

Vin = Code

Offset Binary

* LSB + Offset

where,

• LSB is the least significant bit.

• FSR is the full-scale range. For the DT9820 Series, the full-scale

range is 5.0 V for twos complement coding.

• N is the input resolution (24 bits).

• Vin is the analog voltage.

• Code

OffsetBinary

is the raw count used by the software to represent

the voltage in offset binary notation.

• Code

Twos Complement

is the raw count used by the software to

represent the voltage in twos complement notation.

• Offset is the actual minus full-scale value. The minus full-scale

value is

−

2.5 V for twos complement coding.

For example, assume that you are using a DT9822 with a range of
±2.5 V. If the software returns a code of C00000h for the analog input
operation, determine the analog input voltage as follows:

LSB =

5.0

= 0.000000298023

16777216

Содержание DT9820 Series

Страница 1: ...DT9820 Series UM 18221 B User s Manual...

Страница 2: ...ements of patents or other rights of third parties which may result from its use No license is granted by implication or otherwise under any patent rights of Data Translation Inc Use duplication or di...

Страница 3: ...fications to this equipment not expressly approved by Data Translation could void your authority to operate the equipment under Part 15 of the FCC Rules Note This product was verified to meet FCC requ...

Страница 4: ......

Страница 5: ...essories 6 Chapter 2 Principles of Operation 7 Analog Input Features 9 Input Resolution 9 Analog Input Channels 10 Input Ranges and Gains 10 A D Sample Clock 12 Triggers 14 Analog Input Conversion Mod...

Страница 6: ...er Capabilities 29 Chapter 4 Programming Flowcharts 41 Single Value Operations 43 Continuous A D Operations 45 Simultaneous Operations 47 Chapter 5 Calibration 57 Running the Calibration Utility 59 Ca...

Страница 7: ...Contents vii Appendix B Connector Pin Assignments 81 Index 87...

Страница 8: ...Contents viii...

Страница 9: ...operating systems It is assumed that you have some familiarity with data acquisition principles and that you understand your application What You Should Learn from this Manual This manual provides det...

Страница 10: ...ccur Appendix A Specifications lists the specifications of the modules Appendix B Connector Pin Assignments shows the pin assignments for the connectors and the screw terminal assignments for the modu...

Страница 11: ...ices without programming DataAcq SDK User s Manual UM 18326 For programmers who are developing their own application programs using the Microsoft C compiler this manual describes how to use the DT Ope...

Страница 12: ...you run into problems installing or using a DT9820 Series function module the Data Translation Technical Support Department is available to provide technical assistance Refer to Chapter 6 for more in...

Страница 13: ...1 1 Overview Features 2 Supported Software 4 Accessories 6...

Страница 14: ...nsion hubs do require external power DT9820 Series function modules reside outside of the PC and install with a single cable to ease installation Modules can be hot swapped or plugged and unplugged wh...

Страница 15: ...ters Input gains of 1 2 4 8 16 32 and 64 Continuously paced analog input operations One 8 bit digital input port high to low transitions on digital input lines 0 to 3 can start A D conversions on A D...

Страница 16: ...brated when the module is powered up Refer to Chapter 5 for more information on this utility Quick Data Acq application This software is provided on the Data Acquisition OMNI CD that is shipped with t...

Страница 17: ...ies with the DT Open Layers standard DTx EZ Order this optional software package if you want to use ActiveX controls to access the capabilities of the DT9820 Series boards using Microsoft Visual Basic...

Страница 18: ...ble as an accessory product for the DT9820 Series EP316 a 5 meter USB cable that connects the USB connector of the DT9820 Series function module to the USB connector on the host computer STP9820 a 100...

Страница 19: ...7 2 Principles of Operation Analog Input Features 9 Analog Output Features 23 Digital I O Features 26...

Страница 20: ...V D D GND High Speed Isolated Data Path CH 0 24 Bit A D CH 1 24 Bit A D CH 2 24 Bit A D CH 3 24 Bit A D 1 2 4 8 16 32 64 Gain Selectable 100 Hz Filter 1 2 4 8 16 32 64 Gain Selectable 100 Hz Filter 1...

Страница 21: ...ution described on this page Analog input channels described on this page Input ranges and gains described on page 10 A D sample clock sources described on page 12 Analog input conversion modes descri...

Страница 22: ...fy whether to use a 100 Hz filter to filter the input on each channel By default the filters are turned off Refer to the documentation for your software package for information on turning filters on a...

Страница 23: ...e best sampling accuracy for that channel You can either specify the gain as part of the single value operation or you can specify the gain using an analog input gain list Enter the gain in the gain l...

Страница 24: ...se 60 Hz or 50 Hz operations using the Control Panel refer to the DT9820 Series Getting Started Manual for information on how to configure the driver Using software specify the clock source as interna...

Страница 25: ...specify a sampling frequency of at least 40 Hz Doing so avoids an error condition called aliasing in which high frequency input components erroneously appear as lower frequencies after sampling 50 Hz...

Страница 26: ...D conversion is either started or paused as shown in Table 4 When the operation is paused the driver does not empty the data buffers therefore the buffers contain the data that was acquired before th...

Страница 27: ...essage occurs Using software specify the trigger source as a digital event trigger Refer to the example programs on the Data Acq OMNI CD for an example of using a digital event trigger Note All the di...

Страница 28: ...host memory all subsequent triggers are ignored In an abrupt stop the module stops acquiring samples immediately the acquired data is not transferred to host memory and all subsequent triggers or ret...

Страница 29: ...put resolution 24 bits Vin is the analog voltage Code is the raw count used by the software to represent the voltage in binary notation Offset is the actual minus full scale value The minus full scale...

Страница 30: ...resolution 24 bits Vin is the analog voltage CodeOffsetBinary is the raw count used by the software to represent the voltage in offset binary notation CodeTwos Complement is the raw count used by the...

Страница 31: ...an 120 Samples s the minimum buffer size that you should specify is 16 samples For sampling rates greater than 240 Samples s the minimum buffer size that you should specify is 128 samples Specify the...

Страница 32: ...r can clear this error To avoid this error use a slower sampling rate Note The LED on the front panel will not blink green if the hardware detects an error Synchronizing A D Subsystems You synchronize...

Страница 33: ...the subsystems When started the subsystems are triggered simultaneously when a high to low transition occurs on digital input line 0 Similarly if you want to trigger A D subsystems 2 and 3 simultaneou...

Страница 34: ...k source as the internal A D sample clock for the A D subsystems using software Ensure that you specify the same frequency for the internal clock sources Then specify the trigger source for the A D su...

Страница 35: ...s The DT9822 module supports two DC level analog output channels DAC0 and DAC1 Each DAC is a separate D A subsystem Refer to the DT9820 Series Getting Started Manual for information on how to wire ana...

Страница 36: ...ce or buffer Single value operations stop automatically when finished you cannot stop a single value operation Data Format Data from the host computer must use offset binary data encoding for analog o...

Страница 37: ...by the software to represent the voltage Vout is the analog voltage Offset is the minus full scale value or 5 V For example if you want to output a voltage of 4 7V determine the code value as follows...

Страница 38: ...tart A D conversions you can use high to low transitions on digital inputs 4 to 7 to stop A D conversions Refer to page 14 for more information Note All the digital inputs must be in the high state be...

Страница 39: ...specify the digital I O port and a gain of 1 the gain is ignored Data is then read from or written to the digital I O lines For a single value operation you cannot specify a clock or trigger source Si...

Страница 40: ...Chapter 2 28...

Страница 41: ...29 3 Supported Device Driver Capabilities...

Страница 42: ...able lists the subsystem types The first column in the table lists all possible subsystem capabilities A description of each capability is followed by the parameter used to describe that capability in...

Страница 43: ...Yes Continuous Operation until Trigger Event Support OLSSC_SUP_CONTINUOUS_ PRETRIG Continuous Operation before and after Trigger Event OLSSC_SUP_CONTINUOUS_ ABOUTTRIG DT Connect Support OLSSC_SUP_DTC...

Страница 44: ...Yes Supports Gap Free Data with Single DMA OLSSC_SUP_GAPFREE_SINGLEDMA Supports Gap Free Data with Dual DMA OLSSC_SUP_GAPFREE_DUALDMA Triggered Scan Mode Triggered Scan Support OLSSC_SUP_TRIGSCAN Max...

Страница 45: ...OLSSC_SUP_SEQUENTIAL_CGL Yes Zero Start Sequential Channel Gain List Support OLSSC_SUP_ZEROSEQUENTIAL_ CGL Yes Random Channel Gain List Support OLSSC_SUP_RANDOM_CGL Yes Simultaneous Sample and Hold Su...

Страница 46: ...SUP_EXP727 Channel Type SE Support OLSSC_SUP_SINGLEENDED SE Channels OLSSC_MAXSECHANS 0 0 0 0 0 DI Support OLSSC_SUP_DIFFERENTIAL Yes Yes Yes Yes DI Channels OLSSC_MAXDICHANS 1 2 1 1 0 Filters Filter...

Страница 47: ...OFTTRIG Yes Yes Yes Yes External Trigger Support OLSSC_SUP_EXTERNTRIG Yesb Positive Threshold Trigger Support OLSSC_SUP_THRESHTRIGPOS Negative Threshold Trigger Support OLSSC_SUP_THRESHTRIGNEG Analog...

Страница 48: ...1 0 1 0 Maximum Throughput OLSSCE_MAX_THROUGHPUT 960 Hzj 0 0 0 Minimum Throughput OLSSCE_MIN_THROUGHPUT 7 5 Hzj 1 0 0 0 0 Counter Timers Cascading Support OLSSC_SUP_CASCADING Event Count Mode Support...

Страница 49: ...e Support OLSSC_SUP_GATE_HIGH_EDGE Low Edge Gate Type Support OLSSC_SUP_GATE_LOW_EDGE Level Change Gate Type Support OLSSC_SUP_GATE_LEVEL High Level Gate Type with Input Debounce Support OLSSC_SUP_GAT...

Страница 50: ...to low transition on dig ital input line 2 can trigger A D subsystem 2 and a high to low transition on digital input line 3 can trigger A D subsystem 3 Similarly a high to low transition on digital i...

Страница 51: ...ge and for the 0 1 to 2 5 V range Twos comple ment encoding is used for the 2 5 V to 2 5 V range i The internal oscillator is 4 9152 MHz for 60 Hz operation and 4 0960 MHz for 50 Hz operation j The ma...

Страница 52: ...Chapter 3 40...

Страница 53: ...41 4 Programming Flowcharts Single Value Operations 43 Continuous A D Operations 45 Simultaneous Operations 47...

Страница 54: ...ustration purposes the DataAcq SDK functions are shown however the concepts apply to all DT Open Layers software Note that many steps represent several substeps if you are unfamiliar with the detailed...

Страница 55: ...itialize the device driver and get the device handle with olDaInitialize Configure the subsystem using olDaConfig Go to the next page Specify A D for an analog input subsystem D A for an analog output...

Страница 56: ...session using olDaTerminate Yes Continued from previous page 1 Read a single analog input value or a digital input value from the specified channel line Each A D subsystem contains one differential a...

Страница 57: ...DaGetDASS Initialize the device driver and get the device handle with olDaInitialize Set up the channel list and channel parameters see page 49 Set up the clocks and triggers see page 50 Set the subsy...

Страница 58: ...up the operation see page 56 Start the operation with olDaStart Continued from previous page 1 After configuration if using an internal clock you can use olDaGetClockFrequency to get the actual frequ...

Страница 59: ...ist Prestart the subsystems on the simultaneous start list with olDaSimultaneousPreStart Allocate a simultaneous start list using olDaGetSSList Follow the continuous A D flowchart for each A D subsyst...

Страница 60: ...tage input range as 0 to 2 5V 0 10 to 2 5V or 2 5V the default The input range and the gain determine the effective input range See page 10 for more information For D A subsystems on the DT9822 specif...

Страница 61: ...channel 0 that is entered in the channel gain list by default For A D operations specify a gain of 1 2 4 8 16 32 or 64 By default the gain is 1 Specify the size of the A D channel list and gain list...

Страница 62: ...ital input 6 pauses A D subsystem 2 and a high to low transition on digital input 7 pauses A D subsystem 3 If you specified the trigger source as OL_TRG_DIGITALEVENT a high to low transition on digita...

Страница 63: ...apping mode using olDaSetWrapMode A minimum of three buffers is recommended Specify the window in which to post the messages using olDaSetWndHandle Specify the width of the buffer as 4 bytes Specify a...

Страница 64: ...the allocated buffer for immediate processing using olDaFlushFromBufferInprocess Deal with messages and buffers see page 53 The buffer into which in process data was copied was put onto the done queu...

Страница 65: ...the number of samples in the buffer using olDmGetValidSamples Go to the next page The most likely error messages include OLDA_WM_OVERRUN and OLDA_WM_TRIGGERERROR OLDA_WM_TRIGGERERROR is reported if a...

Страница 66: ...array using olDmCopyFromBuffer Get a pointer to the buffer using olDmGetBufferPtr Process the data buffer in your program Put the buffer on the ready queue using olDaPutBuffer Recycle the buffer if y...

Страница 67: ...nd flushes all buffers to the done queue Stop in an orderly way Stop the operation in an orderly way using olDaStop olDaStop stops the operation on the subsystem in the orderly way the current in proc...

Страница 68: ...ine the number of buffers on the done queue using olDaGetQueueSize Retrieve each buffer on the done queue using olDaGetBuffer Free each buffer retrieved from the done queue using olDmFreeBuffer More b...

Страница 69: ...57 5 Calibration Running the Calibration Utility 59 Calibrating the Analog Output Subsystem 60...

Страница 70: ...uire calibration for initial use It is recommended that you check and if necessary readjust the calibration of the analog output circuitry on the DT9822 function modules every six months Note Ensure t...

Страница 71: ...your hard disk This program folder was created when you installed the DT9820 Series software 2 Double click the Calibration Utility icon in the program folder 3 Select the name of the DT9822 function...

Страница 72: ...005 V 5 In the DAC0 Voltage box click 9 375 V and verify that your external meter display reads 9 375 V within 12 mV 6 Connect Analog Output 1 TB3 4 to the positive side of the precision voltage meter...

Страница 73: ...Calibration 61 5 5 5 5 5 5 5 5 5 Once you have finished this procedure the analog output circuitry is calibrated To close the Calibration Utility click Done...

Страница 74: ...Chapter 5 62...

Страница 75: ...63 6 Troubleshooting General Checklist 64 Service and Support 67 If Your Board Needs Factory Service 71...

Страница 76: ...heck that your system meets the requirements stated in the DT9820 Series Getting Started Manual 4 Check that you have installed your hardware properly using the instructions in the DT9820 Series Getti...

Страница 77: ...structions in the DT9820 Series Getting Started Manual The module is overheating Check environmental and ambient temperature consult the module s specifications on page 79 of this manual and the docum...

Страница 78: ...the instructions in the DT9820 Series Getting Started Manual The module is set up for differential inputs while the transducers are wired as single ended inputs or vice versa Check your wiring and en...

Страница 79: ...arantee prompt response and are very affordable contact your local sales office for details Refer to the Data Translation Support Policy located at the end of this manual for a list of services includ...

Страница 80: ...lude the following information Your name please include proper spelling Your company or organization please include proper spelling A phone number An email address where you can be reached The hardwar...

Страница 81: ..._______________ graphics adapter _____________________________ data bus _________________________ I have the following boards and applications installed in my system ____________________________ _____...

Страница 82: ...you are experiencing Your contract number if applicable and Your product serial number or purchase date Omitting any of the above information may delay our ability to resolve your issue Fax Please ph...

Страница 83: ...number of your nearest distributor are listed in your Data Translation catalog All return shipments to Data Translation must be marked with the correct RMA number to ensure proper processing 2 Using...

Страница 84: ...Chapter 6 72...

Страница 85: ...73 A Specifications...

Страница 86: ...ations Number of analog inputs 4 Differential Number of gains 7 1 2 4 8 16 32 64 Resolution 24 bits Data encoding Binary Offset Binary System accuracy full scale Gain 1 Gain 2 Gain 4 Gain 8 Gain 16 Ga...

Страница 87: ...0390625 V 0 078125 V 0 15625 V 0 3125 V 0 625 V 1 25 V 2 5 V Drift Zero Gain 100 nV 5 nV Gain C 30 ppm C Input impedance Power Off Power On 100 k 100 M 20 k in series with 4700 pF Input bias current 2...

Страница 88: ...NOB at 7 5 Hz input 18 bits typical Channel crosstalk 100 dB 1 kHz Isolation Voltage 500 V DC to computer ground Software selectable input filter 100 Hz Minimum Data Throughput Internal Clock 7 5 S s...

Страница 89: ...4 LSBs Differential linearity 1 0 LSB monotonic Output range 5 V bipolar Zero error Software adjustable to zero Gain error 6 LSBs Current output 5 mA minimum 5 V 1 k Output impedance 0 3 typical Capa...

Страница 90: ...e to stop A D conversions where line 4 corresponds to A D channel 0 line 5 corresponds to A D channel 1 line 6 corresponds to A D channel 2 and line 7 corresponds to A D channel 3 Termination 22 k Pul...

Страница 91: ...r Output driver high voltage Output driver low voltage TTL 2 4 V minimum IOH 1 mA 0 5 V maximum IOL 12 mA Back EMF diodes Yes Table 11 Power Physical and Environmental Specifications Feature Specifica...

Страница 92: ...tions for the DT9820 Series function modules Table 12 DT9820 Series Cable and Connector Specifications Feature Specifications USB cable 2 meter Type A B USB cable Data Translation part 17394 or AMP pa...

Страница 93: ...81 B Connector Pin Assignments...

Страница 94: ...Digital Input Line 2 8 Digital Input Line 1 9 Digital Input Line 0 10 5 V Isolated Input Outputa 11 Isolated Digital Ground 12 Isolated Analog Common 13 Analog Input Subsystem 03 14 Isolated Analog C...

Страница 95: ...subsystems is activated which in turn activates power to the module You can externally power the 5 V isolated output signal This allows you to retain the last value that was written to the digital ou...

Страница 96: ...High 2 CH0L Analog Input Subsystem 0 Low 3 AGND Analog Ground 4 CH1H Analog Input Subsystem 1 High 5 CH1L Analog Input Subsystem 1 Low 6 AGND Analog Ground TB2 1 CH2H Analog Input Subsystem 2 High 2 C...

Страница 97: ...IN4 Digital Input 4 6 DIN5 Digital Input 5 7 DIN6 Digital Input 6 8 DIN7 Digital Input 7 9 DGND Digital Ground a 5 V output is available only when one of the subsystems is activated which in turn acti...

Страница 98: ...Appendix B 86...

Страница 99: ...nnels 23 conversion mode 24 data format 24 gain 24 output ranges 24 resolution 23 specifications 77 B banks digital I O 26 base clock frequency 36 binary data encoding 35 buffers 19 32 dealing with fo...

Страница 100: ...60 data encoding 24 binary 16 35 twos complement 16 35 data flow modes continuous post trigger operations 31 single value operations 31 data format analog input 16 analog output 24 data transfer 19 Da...

Страница 101: ...s 79 80 G gain analog input 10 analog output 24 number of 33 gap free data 32 GCL depth 33 H help 63 I inprocess buffers 32 52 input ranges 10 internal clock 36 J J1 connector pin assignments 82 84 L...

Страница 102: ...single value operations 43 olDaPutBuffer 51 54 olDaPutDassToSSList 47 olDaPutSingleValue 44 olDaReleaseDASS in continuous A D operations 56 in single value operations 44 olDaReset 55 olDaSetChannelFil...

Страница 103: ...LTIPLE 32 OLSSC_SUP_WRPSINGLE 32 OLSSC_SUP_ZEROSEQUENTIAL_ CGL 33 OLSSCE_BASECLOCK 36 OLSSCE_MAX_THROUGHPUT 36 OLSSCE_MAXCLOCKDIVIDER 36 OLSSCE_MAXRETRIGGER 33 OLSSCE_MIN_THROUGHPUT 36 OLSSCE_MINCLOCK...

Страница 104: ...wer 79 80 specifying a single digital I O line 26 stopping an operation 16 55 STP9820 screw terminal panel 6 subsystem descriptions D A 23 DIN and DOUT 26 subsystem parameters setting 48 support e mai...

Страница 105: ...s 5 Visual C programs 5 voltage ranges 10 number of 34 W Windows messages 31 World Wide Web 70 wrap mode 19 writing programs in C C 5 writing programs in Visual Basic 5 writing programs in Visual C 5...

Страница 106: ...Index 94...

Страница 107: ...ITTEN EITHER IN FACT OR BY OPERATION OF LAW STATUTORY OR OTHERWISE INCLUDING WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE WHICH DATA TRANSLATION SPECIFICALLY DISCLAIMS DATA TRANS...

Страница 108: ......

Страница 109: ...monitoring by internet electronic mail b telephone support for problem determination verification and resolution or instruction as to work around as applicable on a call back basis during Data Transl...

Страница 110: ...unless an alternative commencement date is identified in the Support Order Form The initial term will automatically be extended for additional terms of one 1 year unless Support Services are terminate...

Страница 111: ...s for installation training file conversion costs optional products and services directories shipping charges or the cost of any recommended hardware third party software or third party software maint...

Страница 112: ...Data Translation Support Policy...

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