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National Instruments SCXI-1121 User's Manual

1. 2 15 Front Connector 2 16 Front Connector Signal Descriptions 2 18 Analog Input Channels 2 20 Excitation Channels 2 22 Temperature Sensor Connection 2 22 Connector and Shell Assembly 2 22 SCXI 1320 SCXI 1328 and SCXI 1321 Terminal Blocks 2 24 Rear Signal Connector 2 37 Rear Signal Connector Signal Descriptions 2 38 Analog Output Signal Connections 2 39 Digital I O Signal Connections 2 40 Timing Requirements and Communication Protocol 2 42 Communication Signals 2 42 Contents SCXI 1121 User Manual vi www natinst com Chapter 3 Theory of Operation Functional Overview
2. 1 G Power off 50 k Overload 50 k Output resistance Multiplexed Output mode 100 Parallel Output mode 330 1 Includes the combined effects of gain offset and hysteresis and nonlinearity Appendix A Specifications SCXI 1121 User Manual A 2 www natinst com Filtering jumper selectable 4 Hz 10 dB or 10 kHz 3 dB 3 pole RC Noise 400 kHz bandwidth 1 Input gain 1 000 4 Hz filter 100 nVrms 10 kHz filter 4 Vrms Output gain 1 4 Hz 150 Vrms 10 kHz 1 mVrms Output selection time with 5 V step all gains 2 0 012 accuracy 5 2 sec typical 7 sec maximum 0 006 accuracy 10 sec 0 0015 accuracy 20 sec Rise time 4 Hz 0 12 sec 10 kHz 70 sec Slew rate 0 15 V sec Operating common mode voltage 50 Hz or 60 Hz Channel to channel or Channel to earth 250 Vrms2 Common mode rejection ratio 50 or 60 Hz 1 k in input leads
3. 5 3 Single Channel Measurements 5 4 Direct Measurements 5 4 Indirect Measurements 5 5 Scanning Measurements 5 7 1 Data Acquisition Board Setup Programming 5 7 Contents National Instruments Corporation vii SCXI 1121 User Manual 2 Module Programming 5 10 3 Programming the Slot 0 Hardscan Circuitry 5 13 4 Acquisition Enable Triggering and Servicing 5 14 Scanning Examples 5 15 Example 1 5 15 Example 2 5 15 Example 3 5 16 Appendix A Specifications Appendix B Rear Signal Connector Appendix C SCXIbus Connector Appendix D SCXI 1121 Front Connector Appendi
4. 2 36 Figure 2 12 SCXI 1328 Parts Locator Diagram 2 37 Figure 2 13 SCXI 1321 Parts Locator Diagram 2 38 Figure 2 14 SCXI 1121 Rear Signal Connector Pin Assignment 2 39 Figure 2 15 SCANCLK Timing Requirements 2 43 Figure 2 16 Slot Select Timing Diagram 2 44 Figure 2 17 Serial Data Timing Diagram 2 45 Figure 2 18 Configuration Register Write Timing Diagram 2 46 Figure 2 19 SCXI 1121 Module ID Register Timing Diagram 2 47 Figure 3 1 SCXI 1121 Block Diagram 3 1 Figure 3 2 SCXIbus Connector Pin Assignment 3 3 Figure 3 3 Digital Interface Circuitry Block Diagram 3 6 Figure 3 4 SCXI 1121 Digital Control 3 7 Figure 3 5 Analog Input Block Diagram 3 9 Figure 3 6 Analog Output Circuitry
5. 160 dB minimum at 4 Hz bandwidth NMR 50 or 60 Hz 60 dB at 4 Hz bandwidth Input protection continuous 250 Vrms maximum Output protection Continuous short to ground Power dissipation 7 5 W maximum 1 Includes the combined effects of the SCXI 1121 and the AT MIO 16F 5 2 Module tested following the UL1244 standard to twice the working voltage 1000 Vrms Appendix A Specifications National Instruments Corporation A 3 SCXI 1121 User Manual RTD Mode Excitation current 0 15 mA 0 04 0 45 mA 0 2 Maximum load resistance 10 k Drift 40 ppm C Lead resistance effect Negligible 4 wire measurement Resistance range 10 k maximum Strain Gauge Mode Bridge types Quarter half and full bridge Bridge completion Two 4 5 k 0 05 ratio tolerance resistors Excitation voltage 3 333 V 0 04 or 10 V 0 2 Resistance range 120 minimum at 3 333 V 800 minimum at 10 V Half bridge voltage VEXT 2 0 04 Cold Junction Sen
6. 3 2 1 3 2 1 3 2 1 Chapter 2 Configuration and Installation National Instruments Corporation 2 7 SCXI 1121 User Manual Position AB R1 connects the analog reference to the SCXIbus guard Position A R0R1 is the parking position and the factory setting Position AB R2 enables the Pseudodifferential Reference mode and connects the analog reference to the OUTREF pin on the rear signal connector Select this mode when the SCXI 1121 has to operate with data acquisition boards that have a nonreferenced single ended NRSE input It is not recommended to use differential input data acquisition boards when jumper W33 is in the AB R2 position Table 2 2 Jumper W33 Settings Jumper Description Configuration W33 Factory setting in parking position W33 Connects the analog reference to AOGND pins 1 and 2 of the rear signal connector W33 Connects SCXIbus guard to the analog reference W33 Enables the Pseudodifferential Reference mode pin 19 of the rear signal connector is connected to the analog reference A B R2 R 1 R 0 A B R2 R 1 R 0 A B R2 R 1 R 0 A B R2 R 1 R 0 Chapter 2 Configuration and Installation SCXI 1121 User Manual 2 8 www natinst c
7. 3 15 Figure 3 7 Single Module Parallel Scanning 3 17 Figure 3 8 Single Module Multiplexed Scanning Direct 3 18 Figure 3 9 Single Module Multiplexed Scanning Indirect 3 19 Figure 3 10 Multiple Module Multiplexed Scanning 3 19 Figure 3 11 Multiple Chassis Scanning 3 20 Figure B 1 SCXI 1121 Rear Signal Connector Pin Assignment B 1 Figure C 1 SCXIbus Connector Pin Assignment C 2 Figure D 1 SCXI 1121 Front Connector Pin Assignment D 2 Figure E 1 SCXI 1340 Installation E 4 Contents National Instruments Corporation ix SCXI 1121 User Manual Figure E 2 SCXI 1180 Rear Connections E 9 Figure E 3 SCXI 1180 Front Panel Installation E 10 Figure E 4 Cover Removal E 11 Figure F 1 Revision A and B SCXI 1121 Signal Conditioning Module F 1 Figure F 2 Revision A and B SCXI 1
8. 10 to 90 noncondensing Safety Designed in accordance with IEC61010 1 UL 3111 1 and CAN CSA C22 2 No 1010 1 for electrical measuring and test equipment Approved at altitudes up to 2000 meters Installation Category II Pollution Degree 2 TK 1 a b RT ln c RT ln 3 RT 50000 VTEMPOUT 2 5 VTEMPOUT National Instruments Corporation B 1 SCXI 1121 User Manual B Rear Signal Connector This appendix describes the pinout and signal names for the SCXI 1121 50 pin rear signal connector including a description of each connection Figure B 1 shows the pin assignments for the SCXI 1121 rear signal connector Figure B 1 SCXI 1121 Rear Signal Connector Pin Assignment RSVD SERCLK DIG GND SLOT0SEL DAQD A SERDATIN OUTREF MCH4 MCH3 MCH2 MCH1 MCH0 AOGND SCANCLK SERDATOUT DIG GND MCH4 MCH3 MCH2 MCH1 MCH0 AOGND 49 50 47 48 45 46 43 44 41 42 39 40 37 38 35 36 33 34 31 32 29 30 27 28 25 26 23 24 21 22 19 20 17 18 15 16 13 14 11 12 9 10 7 8 5 6 3 4 1 2 Appendix B Rear Signal Connector SCXI 1121 User Manual B 2 www natinst com Rear Signal Connector Signal Descriptions See the Timing Requirements and Communication Protocol section in Chapter 2 Configuration and Insta
9. 5 V EGND2 EX1 EGND3 EX3 CH3 EX2 CH2 EGND1 CH1 EGND0 EX0 EX3 CH3 EX2 DTEMP MTEMP CH2 EX1 CH1 EX0 CH0 CH0 SCAL RSVD RSVD Appendix D SCXI 1121 Front Connector National Instruments Corporation D 3 SCXI 1121 User Manual Front Connector Signal Descriptions Pin Signal Name Description A2 CGND Chassis Ground This pin is tied to the SCXI chassis C2 DTEMP Direct Temperature Sensor This pin connects the temperature sensor to the MCH4 when the terminal block is configured for direct temperature connection A4 5 V 5 VDC Source This pin is used to power the temperature sensor on the terminal block 0 2 mA of source not protected C4 MTEMP Multiplexed Temperature Sensor This pin connects the temperature sensor to the output multiplexer A6 SCAL Shunt Calibration This pin is tied to the SCAL bit and is used to control the SCXI 1321 shunt calibration switch CMOS TTL output not protected C6 C8 RSVD Reserved These pins are reserved Do not connect any signal to these pins A8 C10 C16 C22 C28 No Connect Do not connect any signal to these pins A10 EGND3 Excitation Ground 3 This pin connects to the excitation ground 3 via a 51 k resistor A12 EX3 Positive Excitation Output 3 This pin is connected to the excitation channel 3 positive output C12 EX3 Negative Excitation Output 3 Thi
10. 3 Short the channel inputs of interest together and then to chassis ground 4 Set the amplifier gain to 1 5 Connect the amplifier output to the DMM Make sure that the DMM can achieve the accuracy and resolution you need 6 Adjust the output potentiometer of the channel of interest until the output is 0 3 mV 7 Set the amplifier gain to 1 000 Chapter 3 Theory of Operation National Instruments Corporation 3 13 SCXI 1121 User Manual 8 Adjust the input potentiometer of the channel of interest until the output is 0 6 mV 9 Go to the next channel To avoid erroneous results when nulling the amplifier follow these steps in the order indicated Excitation Adjust When calibrating the excitation channels you should always start with the voltage excitation and then proceed to the current excitation because the voltage excitation reference is used as a voltage reference for the current excitation The following procedure will show you how to recalibrate your module excitation channel to the factory calibration setting 1 Connect a 120 precision resistor to the output of your excitation channel Before connecting this resistor measure it with a four wire ohmmeter and record the exact value you have measured 2 Set up the excitation channel of interest to 3 333 V excitation level 3 Connect your DMM leads to the excitation output as close as possible to the resistor body 4 Adjust the e
11. Excitation Channel Jumpers 3 333 V or 0 150 mA Factory Setting 10 V or 0 450 mA 0 W16 and W26 1 W24 and W25 2 W36 and W37 3 W48 and W49 W16 1 2 3 W26 1 2 3 W16 1 2 3 W26 1 2 3 W24 1 2 3 W25 1 2 3 W24 1 2 3 W25 1 2 3 W36 1 2 3 W37 1 2 3 W36 1 2 3 W37 1 2 3 W48 1 2 3 W49 1 2 3 W48 1 2 3 W49 1 2 3 Chapter 2 Configuration and Installation SCXI 1121 User Manual 2 12 www natinst com Using the Internal Half Bridge Completion Your SCXI 1121 includes half bridge completion for half bridge and quarter bridge setups The completion network consists of two 4 5 k 0 05 ratio tolerance resistors with a temperature coefficient of 5 ppm C These resistors are connected in series To enable the network you must set two jumpers for each input excitation channel pair When the completion network is enabled you cannot access the negative input of the amplifier which preserves the overvoltage protection of the channel Table 2 9 shows how to enable and disable the completion network Note When using the half bridge completion network with a
12. 3 1 SCXIbus Connector 3 3 SCXIbus Connector Signal Descriptions 3 4 Digital Interface 3 6 Digital Control Circuitry 3 7 Analog and Timing Circuitry 3 8 Analog Input Channels 3 8 Excitation Output Channels 3 11 Calibration 3 11 Calibration Equipment Requirements 3 11 Offset Null Adjust 3 12 Excitation Adjust 3 13 Analog Output Circuitry 3 15 Scanning Modes 3 17 Single Module Parallel S
13. 30 27 28 25 26 23 24 21 22 19 20 17 18 15 16 13 14 11 12 9 10 7 8 5 6 3 4 1 2 Chapter 2 Configuration and Installation SCXI 1121 User Manual 2 38 www natinst com Rear Signal Connector Signal Descriptions Pin Signal Name Description 1 2 AOGND Analog Output Ground These pins are connected to the analog reference when jumper W33 is in position AB R0 3 12 MCH0 through MCH4 Analog Output Channels 0 through 4 Connects to the data acquisition board differential analog input channels 19 OUTREF Output Reference This pin serves as the reference node for the analog channels output in the Pseudodifferential Reference mode It should be connected to the analog input sense of the NRSE data acquisition board 24 33 DIG GND Digital Ground These pins supply the reference for data acquisition board digital signals and are tied to the module digital ground 25 SERDATIN Serial Data In This signal taps into the SCXIbus MOSI line to provide serial input data to a module or Slot 0 26 SERDATOUT Serial Data Out This signal taps into the SCXIbus MISO line to accept serial output data from a module 27 DAQD A Data Acquisition Board Data Address Line This signal taps into the SCXIbus D A line to indicate to the module whether the incoming serial stream is data or address information 29 SLOT0SEL Slot 0 Select This signal taps into the SCXIbus INTR line to indicate whether the
14. 5 2 to 5 3 Index National Instruments Corporation Index 11 SCXI 1121 User Manual SCXIbus to SCXI 1121 rear signal connector to DAQ board pin equivalences table 2 41 Slot Select Register description 4 6 register writes 5 2 to 5 4 software optional 1 2 to 1 3 software related resources G 2 specifications analog input A 1 to A 2 cold junction sensor A 3 to A 4 environment A 4 physical A 4 RTD mode A 3 safety A 4 strain gauge mode A 3 SPICLK signal description table 3 4 C 3 SCXIbus equivalents for rear signal connector table 3 5 SCXIbus to SCXI 1121 rear signal connector to DAQ board pin equivalences table 2 41 SS signal table 3 5 C 4 strain gauge mode specifications A 3 T technical support resources G 1 to G 2 temperature sensor signal connections 2 22 terminal blocks 2 30 to 2 31 terminal adapter See SCXI 1343 rear screw terminal adapter terminal blocks See SCXI 1302 50 pin terminal block SCXI 1320 and SCXI 1328 terminal blocks SCXI 1321 terminal block theory of operation 3 1 to 3 20 analog and timing circuitry 3 8 to 3 16 analog input channels 3 8 to 3 11 analog output circuitry 3 15 to 3 16 calibration equipment requirements 3 11 to 3 14 excitation output channels 3 11 block diagram of SCXI 1121 3 1 digital control circuitry 3 7 to 3 8 digital interface 3 6 major components of SCXI 1121 3 2 scanning modes 3 17 to 3 20 multiple chassis scanning 3 20 multipl
15. G GBWP gain bandwidth product GUARD guard signal H hex hexadecimal HSCR hardscan control register Glossary SCXI 1121 User Manual Glossary 4 www natinst com HSRS hardscan reset bit Hz hertz I II input current leakage in inches INTR interrupt signal I O input output K K kelvin L LOAD load bit LSB least significant bit M m meters M megabytes of memory MCH positive analog output channel number signal MCH negative analog output channel number signal MISO master in slave out signal MOD module number bit MOSI master out slave in signal MSB most significant bit Glossary National Instruments Corporation Glossary 5 SCXI 1121 User Manual MTEMP multiplexed temperature sensor MTS multiplexed temperature sensor N NRSE nonreferenced single ended input O ONCE once bit OUTREF output reference signal P ppm parts per million R RAM random access memory RD read bit RESET reset signal rms root mean square RSE referenced single ended input RSVD reserved bit signal RTD resistance temperature detector RTEMP read temperature bit RTI referred to input RTO referred to output RTSI real time system integration Glossary SCXI 1121 User Manual Glossary 6 www natinst com S SCAL bit shunt calibrate bit SCAL signal shunt calibration signal SCANCLK scan clock signal SCANC
16. Make sure DAQD A does not go low or erroneous data will be written to the Configuration Register SLOT0SEL 1 SERCLK 1 and has not changed since SS went low 2 For each bit to be read SERCLK 0 SERCLK 1 Clock the data Read the level of the SERDATOUT line 3 Pull SLOT0SEL low to deassert the SS line and establish conditions for writing a new slot select number to the Slot 0 Slot Select Register 4 If you are not selecting another slot you should write zero to the Slot 0 Slot Select Register SLOT0SEL SERDATIN SERCLK SS 0 1 0 0 0 0 1 1 0 0 0 0 1 1 1 1 Chapter 2 Configuration and Installation SCXI 1121 User Manual 2 46 www natinst com Figure 2 19 illustrates a read of the SCXI 1121 Module ID Register Figure 2 19 SCXI 1121 Module ID Register Timing Diagram For further details on programming these signals refer to Chapter 5 Programming SLOT0SEL SS SERCLK 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 SERDATOUT Tdelay byte 0 2 byte 3 0 byte 2 0 byte 1 0 Tdelay SS high to SERDATOUT high 350 nsec maximum National Instruments Corporation 3 1 SCXI 1121 User Manual 3 Theory of Operation This chapter contains a functional overview of the SCXI 1121 module and explains the operation of each functional unit making up the SCXI 1121 Functional Overview The block diagram in Figure 3 1 illustrates the key fun
17. amperes AB0 positive analog bus 0 line signal AB0 negative analog bus 0 line signal AB0EN analog bus 0 enable bit AB2 positive analog bus 2 line signal AB2 negative analog bus 2 line signal ACH data acquisition board analog input channel number A D analog to digital Glossary SCXI 1121 User Manual Glossary 2 www natinst com AOGND analog output ground signal Arms amperes root mean square AWG American Wire Gauge B BW bandwidth C C Celsius CH positive input channel number signal CH negative input channel number signal CHAN channel select bit CHS chassis bit CHSGND chassis ground signal CJR cold junction reference CLKEN clock enable bit CLKOUTEN scanclock output enable bit CLKSELECT scanclock select bit CNT count bit D D A data address line signal D A digital to analog DAQD A data acquisition board data address line signal dB decibels Glossary National Instruments Corporation Glossary 3 SCXI 1121 User Manual DIG GND digital ground signal DIN Deutsche Industrie Norme DMM digital multimeter DTEMP direct temperature sensor DTS direct temperature sensor E EGND excitation ground number signal EX positive excitation output number signal EX negative excitation output number signal F F Fahrenheit FIFO first in first out FOUTEN forced output enable bit FRT forced retransmit bit
18. interface circuitry Figure 3 3 Digital Interface Circuitry Block Diagram The digital interface circuitry is divided into a data acquisition section and an SCXIbus section The SCXI 1121 connects to the SCXIbus via a 4 24 metral receptacle and to the data acquisition board via a 50 pin ribbon cable header The digital interface circuitry buffers the digital signals from the data acquisition board and from the SCXIbus and sends signals back and forth between the data acquisition board and the SCXIbus Digital Interface SCXIbus Buffered Serial Data Buffered Digital Signal Controls SERDATIN DAQD A SLOT0SEL SERCLK SERDATOUT Rear Signal Connector MISO SPICLK INTR D A MOSI SS Chapter 3 Theory of Operation National Instruments Corporation 3 7 SCXI 1121 User Manual Digital Control Circuitry Figure 3 4 diagrams the SCXI 1121 digital control Figure 3 4 SCXI 1121 Digital Control The digital control section consists of the Configuration Register and the Module ID Register The Configuration Register is a two byte serial in parallel out shift register Data is received on the MOSI line from either Slot 0 or the data acquisition board when SS is enabled and D A indicates data transfer D A low The Configuration Register provides temperature channel selection and channel selection and configures the SCXI 1121 for scanning options All the control bits are fed into a latch befor
19. repetitive writes to the HSCR or several FIFO entries it is important that SS 13 or SS 14 go inactive high between each entry Select another slot or toggle the SLOT0SEL line to temporarily deassert the appropriate SS line If consecutive scan list entries access an SCXI 1121 the module will reload the MUXCOUNTER with the starting channel after each entry Thus two entries with counts of two for one module will yield different behavior than one entry with a count of four For multiple chassis scanning program each Slot 0 with dummy entries to fill the sample counts when the data acquisition board is accessing other chassis Use Slot 13 as the dummy entry slot See Example 3 at the end of this chapter 4 Acquisition Enable Triggering and Servicing At this point you should now continue from where you left off in the 1 Data Acquisition Board Setup Programming section of this chapter Perform the following steps given in your data acquisition board user manual MIO Board User Manual Enable the scanning data acquisition operation Apply a trigger Service the data acquisition operation Lab PC User Manual Lab PC User Manual and PC LPM 16 User Manual Start and service the data acquisition operation Lab LC User Manual Program the sample interval counter Service the data acquisition operation Chapter 5 Programming National Instruments Corporation 5 15 SC
20. whereas LabWindows enhances Microsoft C and QuickBASIC Both packages include extensive libraries for data acquisition instrument control data analysis and graphical data presentation Your National Instruments data acquisition board is shipped with the NI DAQ software NI DAQ has a library of functions that you can call from your application programming environment These functions include routines for analog input A D conversion buffered data acquisition high speed A D conversion analog output D A conversion waveform generation digital I O counter timer SCXI RTSI and self calibration NI DAQ maintains a consistent software interface among its different versions so you can switch between platforms with minimal modifications to your code You can also use the SCXI 1121 together with the PC AT and MC data acquisition boards with NI DAQ software for DOS Windows LabWindows CVI NI DAQ software for DOS Windows LabWindows CVI comes with language interfaces for Professional BASIC Turbo Pascal Turbo C Turbo C Borland C and Microsoft C Kit Component Part Number SCXI 1121 module 181700 01 SCXI 1121 User Manual 320426 01 Chapter 1 Introduction National Instruments Corporation 1 3 SCXI 1121 User Manual for DOS and Visual Basic Turbo Pascal Microsoft C with SDK and Borland C for Windows NI DAQ software for DOS Windows LabWindows is on high density 5 25 in and 3 5 in diskettes You can use the
21. 00000010 to the FIFO Register This corresponds to Slot 1 for three samples b Write 00000001 10000001 to the FIFO Register This corresponds to Slot 4 for two samples c Write 00000001 00000011 to the FIFO Register This corresponds to Slot 3 for four samples Make sure to toggle SLOT0SEL or reselect the FIFO Register from scratch between steps 6a 6b and 6c 7 Follow the procedure given in the 4 Acquisition Enable Triggering and Servicing section earlier in this chapter Example 3 You want to scan four channels on an SCXI 1121 in Slot 4 of Chassis 1 then two channels of an SCXI 1121 in Slot 11 of Chassis 2 one channel of an SCXI 1121 in Slot 3 in Chassis 3 and three channels of an SCXI 1121 in Slot 8 of Chassis 3 Chapter 5 Programming National Instruments Corporation 5 17 SCXI 1121 User Manual Assuming that the modules are cabled and programmed correctly the Slot 0 scan lists should be as follows Other solutions are possible In the section 3 Programming the Slot 0 Hardscan Circuitry earlier in this chapter step 3 consists of the following steps 1 Select Slot 14 in Chassis 1 2 Write XXXXX001 10000011 over MOSI 3 Toggle SLOT0SEL 4 Write XXXXX110 00000101 over MOSI 5 Select Slot 14 in Chassis 2 6 Write XXXXX110 00000011 over MOSI 7 Toggle SLOT0SEL 8 Write XXXXX101 00000001 over MOSI 9 Toggle SLOT0SEL 10 Write XXXXX110 00000011 over MOSI 11
22. 10 9 8 X X X X X X X CHS4 7 6 5 4 3 2 1 0 CHS3 CHS2 CHS1 CHS0 SL3 SL2 SL1 SL0 Chapter 4 Register Descriptions National Instruments Corporation 4 7 SCXI 1121 User Manual Hardscan Control Register HSCR The HSCR contains eight bits that control the setup and operation of the hardscan timing circuitry of Slot 0 To write to the HSCR follow the procedure given in the Register Writes section of Chapter 5 Programming using 13 as the slot number and writing eight bits to the HSCR The register will shift in the data present on the MOSI line bit seven first when Slot 13 is selected by the Slot Select Register Type Write only Word Size 8 bit Bit Map Bit Name Description 7 RSVD Reserved 6 FRT Forced Retransmit This bit when clear causes the scan list in the FIFO to be reinitialized to the first entry thus allowing the scan list to be reprogrammed in two steps instead of having to rewrite the entire list When this bit is set it has no effect 5 RD Read This bit when clear prevents the FIFO from being read When set the FIFO is being read except at the end of a scan list entry during scanning when reading is briefly disabled to advance to the next scan list entry 4 ONCE Once When set this bit will cause the Hardscan circuitry to shut down at the end of the scan list circuitry during a data acquisition When clear the circuitry will wrap around and continue wi
23. 2 11 internal half bridge completion 2 12 to 2 13 fixed jumpers 2 2 parts locator diagrams detailed figure 2 2 general figure 2 1 terminal blocks 2 31 to 2 32 user configurable jumpers 2 2 to 2 3 Configuration Register description 4 3 to 4 5 overview 3 7 write timing diagram 2 45 writing to digital control circuitry 3 7 to 3 8 programming 5 2 to 5 4 slot selection procedure 2 44 to 2 45 connector and shell assembly 2 22 to 2 24 connectors See front connector rear signal connector SCXIbus connector conventions used in manual xi xii Index National Instruments Corporation Index 3 SCXI 1121 User Manual Counter 1 scanning measurements 5 9 to 5 10 current and voltage excitation jumpers 2 9 to 2 10 custom cables 1 5 D D A signal description table 3 4 C 3 SCXIbus equivalents for rear signal connector table 3 5 SCXIbus to SCXI 1121 rear signal connector to DAQ board pin equivalences table 2 41 DAQD A signal See also communication signals description table 2 38 B 2 register writes 5 2 to 5 3 SCXIbus equivalents for rear signal connector table 3 5 SCXIbus to SCXI 1121 rear signal connector to DAQ board pin equivalences table 2 41 data acquisition board setup for scanning measurements 5 7 to 5 9 diagnostic resources online G 1 DIG GND signal table 2 38 B 2 digital control circuitry 3 7 to 3 8 digital interface 3 6 digital signal connections input signals 2 40
24. ID Register further data will be zeros until reinitialization occurs To write to the Configuration Register follow these steps 1 Initial conditions SS asserted low SERDATIN don t care DAQD A 0 indicates data will be written to Configuration Register SLOT0SEL 1 SERCLK 1 and has not transitioned since SS went low 2 For each bit to be written Establish the desired SERDATIN level corresponding to this bit SERCLK 0 SERCLK 1 Clock the data Tlow Thigh SERCLK SERDATIN SERDATOUT Tsetup Thold Tdelay Tlow Minimum low time 65 nsec minimum Thigh Minimum high time 400 nsec minimum Tsetup SERDATIN setup time 200 nsec minimum Thold SERDATIN hold time 200 nsec minimum Tdelay SERDATOUT delay 350 nsec maximum Chapter 2 Configuration and Installation National Instruments Corporation 2 45 SCXI 1121 User Manual 3 Pull SLOT0SEL low to deassert the SS line and establish conditions for writing a new slot select number to the Slot 0 Slot Select Register 4 If you are not selecting another slot you should write zero to the Slot 0 Slot Select Register Figure 2 18 illustrates a write to the SCXI 1121 Configuration Register of the binary pattern 10000011 00001111 Figure 2 18 Configuration Register Write Timing Diagram To read from the Module ID Register follow these steps 1 Initial conditions SS asserted low SERDATIN don t care DAQD A 1
25. Introduction This chapter describes the SCXI 1121 lists the contents of your SCXI 1121 kit describes the optional software optional equipment and custom cables and explains how to unpack the SCXI 1121 kit The SCXI 1121 consists of four isolated input channels and four isolated excitation channels The SCXI 1121 is a module for signal conditioning of strain gauges RTDs thermistors thermocouples volt and millivolt sources 4 to 20 mA current sources and 0 to 20 mA process current sources The SCXI 1121 can operate in two output modes the Parallel Output mode with all four input channels connected in parallel to four data acquisition board channels or the Multiplexed Output mode with all four channels multiplexed into a single data acquisition board channel The SCXI 1121 operates with full functionality with National Instruments MIO 16 boards The SCXI 1121 operates with full functionality with the Lab PC board in single chassis SCXI systems However the Lab PC cannot control multiple chassis SCXI systems You can use the Lab NB the Lab PC the Lab LC and the PC LPM 16 boards with the SCXI 1121 but these boards can control only single chassis SCXI systems and cannot scan the module when it is configured in the Multiplexed Output mode These boards can perform only single channel reads in this mode You can also use the SCXI 1121 with other systems that comply with the specifications given in Chapter 2 Configuration and Installati
26. Register The Slot 0 scan list is created by consecutive writes to the FIFO Register Each write creates a new entry at the end of the scan list The maximum number of entries is 256 To clear the FIFO of all entries clear the HSRS bit in the HSCR Type Write only Word Size 16 bit Bit Map Bit Name Description 15 11 X Don t care bits Unused 10 7 MOD lt 3 0 gt Module Number The value of these bits plus on determines the number of the slot to be accessed for this scan entry For example to access Slot 6 MOD lt 3 0 gt would be 0101 6 0 CNT lt 6 0 gt Count The value of these bits plus one determines how many samples will be taken before the next scan list entry becomes active A value of zero corresponds to one sample and a value of 127 corresponds to 128 samples 15 14 13 12 11 10 9 8 X X X X X MOD3 MOD2 MOD1 7 6 5 4 3 2 1 0 MOD0 CNT6 CNT5 CNT4 CNT3 CNT2 CNT1 CNT0 National Instruments Corporation 5 1 SCXI 1121 User Manual 5 Programming This chapter contains a functional programming description of the SCXI 1121 and Slot 0 Note If you plan to use a programming software package such as NI DAQ LabWindows or LabVIEW with your SCXI 1121 board you do not need to read this chapter Programming Considerations Programming the SCXI 1121 involves writing to the Configuration Register Programming Slot 0 involves writing to the HSCR and FIFO Register Progra
27. after calibration with antisabotage lacquer to avoid tampering with the calibration Table 3 2 lists the potentiometer reference designators that correspond to each channel The resistor used to calibrate the current level must be a precision type with a tempco of 5 ppm or less You should measure and record the resistor value before each calibration procedure The DMM you are using should provide you with the required resolution and accuracy to achieve the calibration levels indicated in the paragraphs above Annual or semi annual calibration is recommended to maintain the accuracy level Table 3 2 Calibration Potentiometer Reference Designators Input Channel Number Amplifier Channel Excitation Channel Input Null Output Null Voltage Mode Current Mode 0 R2 R3 R10 R7 1 R16 R4 R20 R17 2 R26 R5 R30 R27 3 R36 R6 R40 R37 Chapter 3 Theory of Operation National Instruments Corporation 3 15 SCXI 1121 User Manual Analog Output Circuitry Figure 3 6 shows the SCXI 1121 analog output circuitry Figure 3 6 Analog Output Circuitry The SCXI 1121 output circuitry consists of a buffered output multiplexer and channel select hardware The channel select hardware consists of a two bit counter MUXCOUNTER This counter is needed when the board is operating in the Multiplexed Output Mode The counter output is sent to the multiplexer address pins to determine which of the four channels is to be connected to
28. antistatic package to a metal part of your SCXI chassis before removing the module from the package Remove the module from the package and inspect the module for loose components or any other sign of damage Notify National Instruments if the module appears damaged in any way Do not install a damaged module into your SCXI chassis National Instruments Corporation 2 1 SCXI 1121 User Manual 2 Configuration and Installation This chapter describes the SCXI 1121 jumper configurations installation of the SCXI 1121 into the SCXI chassis signal connections to the SCXI 1121 and cable wiring Module Configuration The SCXI 1121 contains 49 jumpers that are shown in the parts locator diagrams in Figures 2 1 and 2 2 Figure 2 1 SCXI 1121 General Parts Locator Diagram Chapter 2 Configuration and Installation SCXI 1121 User Manual 2 2 www natinst com Figure 2 2 SCXI 1121 Detailed Parts Locator Diagram The jumpers are used as follows Fixed jumpers On Revision A and B modules jumper W32 is unused and should not be connected Jumper W45 is reserved and should not be reconfigured On Revision A and B modules jumper W44 carries the SLOT0SEL signal from the rear signal connector after buffering to the SCXIbus INTR line and should be left in the factory set position position 1 On Revision C or later modules jumper W44 does not exist User configurable jumpers Jumper W38 c
29. board When used with an SCXI 1341 SCXI 1342 or SCXI 1344 cable assembly the SCXI 1121 signals match the digital lines of the Lab NB Lab PC Lab PC Lab LC boards and the PC LPM 16 board respectively Table 2 16 lists the equivalences For more information consult Appendix E SCXI 1121 Cabling Chapter 2 Configuration and Installation National Instruments Corporation 2 41 SCXI 1121 User Manual The digital timing signals are pins 36 and 43 Pin 36 is used as a clock by the SCXI 1121 to increment the MUXCOUNTER after each conversion by the data acquisition board during scanning This signal is referred to as SCANCLK See Chapter 3 Theory of Operation for a description of MUXCOUNTER Pin 43 is a reserved digital input The following specifications and ratings apply to the digital I O lines Absolute maximum voltage Input rating 5 5 V with respect to DIG GND Digital input specifications referenced to DIG GND VIH input logic high voltage 2 V minimum VIL input logic low voltage 0 8 V maximum II input current leakage 1 A maximum Digital output specifications referenced to DIG GND VOH output logic high voltage 3 7 V minimum at 4 mA maximum VOL output logic low voltage 0 4 V maximum at 4 mA maximum Table 2 16 SCXIbus to SCXI 1121 Rear Signal Connector to Data Acquisition Board Pin Equivalences SCXIbus Line SCXI 1121 Rear Signal Connector MIO 16 Lab NB Lab PC Lab PC Lab LC PC LPM 1
30. calibration SCXI 1321 terminal block 2 28 to 2 29 signal connections 2 15 to 2 46 front connector 2 16 to 2 36 analog input channels 2 20 to 2 22 connector and shell assembly 2 22 to 2 24 excitation channels 2 22 pin assignments figure 2 17 D 2 SCXI 1320 SCXI 1328 and SCXI 1321 terminal blocks 2 24 to 2 36 signal descriptions table 2 18 to 2 19 D 3 to D 4 temperature sensor connection 2 22 rear signal connector 2 37 to 2 46 analog output 2 39 communication signals 2 42 to 2 46 digital I O 2 40 to 2 41 pin assignments figure 2 37 B 1 signal descriptions table 2 38 B 2 timing requirements and communication protocol 2 42 safety precautions 2 15 to 2 16 SCXIbus connector equivalents for rear signal connector table 3 5 pin assignments figure 3 3 C 2 signal descriptions table 3 4 to 3 5 C 3 to C 4 terminal blocks 2 33 to 2 36 single channel measurements programming 5 4 to 5 6 direct measurements 5 4 to 5 5 multiplexed output 5 4 to 5 5 parallel output 5 4 indirect measurements 5 5 to 5 6 from other modules 5 5 from SCXI 1121 via another module 5 5 5 6 Single Channel Read mode 3 15 SL lt 3 0 gt bits 4 6 Slot 0 Register description 4 5 programming hardscan circuitry 5 13 to 5 14 slot selection slot select timing diagram 2 43 writing 16 bit slot select number to Slot 0 2 43 SLOT0SEL signal See also communication signals description table 2 38 B 2 register writes
31. has been taken by the data acquisition board and causes the SCXI 1121 to change channels 37 SERCLK Serial Clock This signal taps into the SCXIbus SPICLK line to clock the data on the MOSI and MISO lines 43 RSVD Reserved All other pins are not connected National Instruments Corporation C 1 SCXI 1121 User Manual C SCXIbus Connector This appendix describes the pinout and signal names for the SCXI 1121 96 pin SCXIbus connector including a description of each connection Appendix C SCXIbus Connector SCXI 1121 User Manual C 2 www natinst com Figure C 1 shows the pin assignments for the SCXI 1121 SCXIbus connector Figure C 1 SCXIbus Connector Pin Assignment A1 B1 A2 B2 A3 B3 A4 B4 A5 B5 A6 B6 A7 B7 A8 B8 A9 B9 A10 B10 A11 B11 A12 B12 A13 B13 A14 B14 A15 B15 A16 B16 A17 B17 A18 B18 A19 B19 A20 B20 A21 B21 A22 B22 A23 B23 A24 B24 D1 C1 D2 C2 D3 C3 D4 C4 D5 C5 D6 C6 D7 C7 D8 C8 D9 C9 D10 C10 D11 C11 D12 C12 D13 C13 D14 C14 D15 C15 D16 C16 D17 C17 D18 C18 D19 C19 D20 C20 D21 C21 D22 C22 D23 C23 D24 C24 GUARD GUARD GUARD AB0 GUARD GUARD GUARD GUARD GUARD GUARD RESET MISO V V CHSGND CHSGND V V 5 V SPICLK TRIG0 SS GUARD GUARD GUARD GUARD GUARD GUARD GUARD GUARD AB0 CHSGND CHSGND CHSGND CHSGND RSVD D A INTR V V V V MOSI 5 V SCANCON CH
32. information on MOSI is being sent to a module or Slot 0 36 SCANCLK Scan Clock This indicates to the SCXI 1121 that a sample has been taken by the data acquisition board and causes the SCXI 1121 to change channels See the Timing Requirements and Communication Protocol section later in this chapter for more detailed information on timing 37 SERCLK Serial Clock This signal taps into the SCXIbus SPICLK line to clock the data on the MOSI and MISO lines See the Timing Requirements and Communication Protocol section later in this chapter for more detailed information on timing 43 RSVD Reserved All other pins are not connected Chapter 2 Configuration and Installation National Instruments Corporation 2 39 SCXI 1121 User Manual The signals on the rear signal connector can be classified as analog output signals digital I O signals or timing I O signals Signal connection guidelines for each of these groups are given in the following section Analog Output Signal Connections Pins 1 through 12 and pin 19 of the rear signal connector are analog output signal pins Pins 1 and 2 are AOGND signal pins AOGND is an analog output common signal that is routed through jumper W33 to the analog reference on the SCXI 1121 You can use these pins for a general analog power ground tie point to the SCXI 1121 if necessary In particular when using differential input data acquisition boards such as the MIO 16 series it is preferable t
33. it is multiplexed with the other input channels set the RTEMP bit of the Configuration Register high This measurement is only software controlled For hardware control of the temperature sensor reading connect the temperature sensor to MCH4 Notice that MCH4 the DTS reference is hardwired to the chassis ground The multiplexer output connects to the MCH0 and is connected to the data acquisition board analog channel input In the case of the MIO data acquisition boards MCH0 on the rear signal connector corresponds to ACH0 and ACH8 Furthermore you can bus the multiplexed output of the SCXI 1121 via switches to AB0 on the SCXIbus and on to other modules When you use multiple modules you can bus the output of the module via AB0 to the module that is connected to the data acquisition board In this case the AB0 switches of all the modules are closed whereas the output multiplexer of all the modules but the one being read are disabled Refer to Chapters 2 and 5 for further details on how to configure and program multiple modules In addition to the Multiplexed Output mode described in the previous paragraph you can operate the SCXI 1121 in Parallel Output mode In this mode you need no software other than software used with your data acquisition board to control the scanning of the four channels or to perform a single read To access the temperature sensor in this mode configure the temperature sensor in the DTS mode At power
34. jumper settings figure 2 5 to 2 6 jumper W32 2 4 jumper W38 2 4 jumper W44 2 3 to 2 4 output signals 2 40 SCXIbus to SCXI 1121 rear signal connector to DAQ board pin equivalences table 2 41 specifications and ratings 2 41 timing signals 2 41 using jumpers W32 and W38 2 4 to 2 5 direct measurements single channel multiplexed output 5 4 to 5 5 parallel output 5 4 single channel measurements 5 4 to 5 5 direct multiplexed scanning single module 5 11 documentation conventions used in manual xi xii related documentation xii DTEMP signal table 2 18 D 3 DTS mode terminal blocks 2 31 to 2 32 E EGND0 signal table 2 19 D 4 EGND1 signal table 2 19 D 4 EGND2 signal table 2 18 D 3 EGND3 signal table 2 18 D 3 environment specifications A 4 equipment optional table 1 4 EX0 signal table 2 19 D 4 EX0 signal table 2 19 D 4 EX1 signal table 2 19 D 4 EX1 signal table 2 19 D 4 EX2 signal table 2 18 D 3 EX2 signal table 2 18 D 4 EX3 signal table 2 18 D 3 EX3 signal table 2 18 D 3 excitation adjust in calibration 3 13 to 3 14 excitation channels signal connections 2 22 theory of operation 3 11 excitation jumpers 2 9 to 2 13 current and voltage jumpers 2 9 to 2 10 excitation level 2 10 to 2 11 internal half bridge completion 2 12 to 2 13 jumper selection table 2 11 maximum load per excitation channel table 2 11 Index SCXI 1121 User Manual
35. number was written to Slot 0 If multiple chassis are being used only the appropriate slot in the chassis whose address corresponds to the written chassis number will be selected When no communication is taking place between the data acquisition board and any modules it is recommended that 0 be written to the Slot Select Register to ensure that no accidental writes occur 0 1 0 0 1 1 0 1 1 Chassis ID 9 Slot 11 SERDATIN SS X Chassis Y SS 11 Chassis 9 SERCLK SLOT0SEL Tss_dis Tss_en Tclk_wait Tslot0sel _wait Tss _ dis SLOT0SEL low to SS disabled 200 nsec maximum Tclk _ wait SLOT0SEL low to first rising edge on SERCLK 75 nsec minimum Tslot0sel _ wait Last rising edge on SERCLK to SLOT0SEL high 250 nsec minimum Tss _ en SLOT0SEL high to SS enabled 350 nsec maximum Chapter 2 Configuration and Installation SCXI 1121 User Manual 2 44 www natinst com Figure 2 17 shows the timing requirements on the SERCLK and SERDATIN signals You must observe these timing requirements for all communications Tdelay is a specification of the SCXI 1121 Figure 2 17 Serial Data Timing Diagram After the Slot Select line to an SCXI 1121 has been asserted you can write to its Configuration Register and read from its Module ID Register by following the protocols given below The contents of the Module ID Register are reinitialized by deasserting Slot Select After the 32 bits of data are read from the Module
36. removing cover Always install grounding screw To connect the signal to the terminal block use the following procedure 1 Remove the grounding screw of the top cover 2 Snap out the top cover of the shield by placing a screwdriver in the groove at the bottom of the terminal block 3 Slide the signal wires one at a time through the front panel strain relief opening You can add padding or insulation if necessary 4 Connect the wires to the screw terminals For thermistor and RTD connection follow the procedure stated in the Using the SCXI 1321 with RTDs and Thermistors section earlier in this chapter 5 Tighten the larger strain relief screws 6 Snap the top cover back in place 7 Reinsert the grounding screw to ensure proper shielding 8 Connect the terminal block to the SCXI 1121 front connector as explained in the Terminal Block Installation section later in this chapter Figure 2 11 shows a parts locator diagram for the SCXI 1320 terminal block Figure 2 12 shows a parts locator diagram for the SCXI 1328 terminal block Figure 2 13 shows a parts locator diagram for the SCXI 1321 terminal block Chapter 2 Configuration and Installation SCXI 1121 User Manual 2 34 www natinst com Figure 2 11 SCXI 1320 Parts Locator Diagram Chapter 2 Configuration and Installation National Instruments Corporation 2 35 SCXI 1121 User Manual Figure 2 12 SCXI 1328 Parts Locator Diagram Chapter 2 Configu
37. ribbon cable to the adapter board rear connector This is the 50 pin connector of the SCXI 1344 cable 4 Plug the adapter board front connector to the module rear signal connector Make sure a corner of the adapter board enters the upper board guide of the chassis 5 Screw the rear panel to the threaded strips in the rear of the chassis 6 For an SCXI 1341 connect the loose end of the ribbon cable to the Lab NB Lab PC or Lab PC I O connector For an SCXI 1344 connect the two 26 pin connectors to the Lab LC according to the instructions given in the Hardware Installation section of Chapter 2 Configuration and Installation of the Lab LC User Manual Check the installation SCXI 1342 PC LPM 16 Cable Assembly The SCXI 1342 PC LPM 16 cable assembly connects a PC LPM 16 board to an SCXI 1121 module The SCXI 1342 cable assembly consists of two pieces an adapter board and a 50 conductor ribbon cable that connects the PC LPM 16 board to the adapter board The adapter board converts the signals from the PC LPM 16 I O connector to a format compatible with the SCXI 1121 rear signal connector pinout The adapter board also has an additional male breakout connector that makes the unmodified PC LPM 16 signals accessible to an SCXI 1180 feedthrough panel or an SCXI 1181 breadboard module The adapter board gives the PC LPM 16 full access to the digital control lines and analog signals but the PC LPM 16 cannot scan channels in Multiplexed m
38. selected channel output or the MTEMP signal is driven onto the MCH0 pins of the rear signal connector If RTEMP is cleared to zero the selected channel output is used as the module output If RTEMP is set to one the MTEMP signal is used as the module output The module output will only be driven when FOUTEN is cleared to 0 or SCANCON is active low while SCANCONEN is cleared 4 RSVD Reserved This bit should always be written to zero 3 SCANCLKEN Scan Clock Enable This bit determines whether MUXCOUNTER will increment on each clock signal the clock source is determined by CLKSELECT or keep its loaded value If SCANCLKEN is set to one MUXCOUNTER will be clocked during scans If SCANCLKEN is cleared to zero MUXCOUNTER will not be clocked 2 SCANCONEN Scan Control Enable This bit when high enables the SCANCON signal 1 AB0EN Analog Bus 0 Enable This bit determines whether Analog Bus 0 on the SCXIbus drives MCH0 on the rear signal connector If AB0EN is cleared to zero Analog Bus 0 does not drive MCH0 If AB0EN is set to one Analog Bus 0 drives MCH0 through a buffer and a Analog Bus 0 is connected to MCH0 Chapter 4 Register Descriptions National Instruments Corporation 4 5 SCXI 1121 User Manual 0 FOUTEN Forced Output Enable This bit determines whether the module will drive the MCH0 pins on the rear signal connector with either the selected channel output or the MTEMP signal dependi
39. text or characters that you should enter from the keyboard sections of code programming examples and syntax examples This font is also used for the proper names of disk drives paths directories programs subprograms subroutines device names functions operations variables filenames and extensions and code excerpts monospace italic Italic text in this font denotes text that is a placeholder for a word or value that you must supply Related Documentation The following documents contain information that you may find helpful as you read this manual AT MIO 16 User Manual part number 320476 01 AT MIO 16D User Manual part number 320489 01 AT MIO 16F 5 User Manual part number 320266 01 AT MIO 16X User Manual part number 320488 01 AT MIO 64F 5 User Manual part number 320487 01 Lab LC User Manual part number 320380 01 Lab NB User Manual part number 320174 01 Lab PC User Manual part number 320205 01 Lab PC User Manual part number 320502 01 MC MIO 16 User Manual Revisions A to C part number 320130 01 MC MIO 16 User Manual Revision D part number 320560 01 NB MIO 16 User Manual part number 320295 01 NB MIO 16X User Manual part number 320157 01 PC LPM 16 User Manual part number 320287 01 SCXI 1000 1001 User Manual part number 320423 01 National Instruments Corporation 1 1 SCXI 1121 User Manual 1
40. the data acquisition board You want to scan channels 1 through 3 on the SCXI 1121 in Slot 1 channels 0 and 1 on the SCXI 1121 in Slot 4 and channels 3 and 2 on the SCXI 1121 in Slot 3 The programming steps are as follows 1 Program your data acquisition board as described in the 1 Data Acquisition Board Setup Programming section Chapter 5 Programming SCXI 1121 User Manual 5 16 www natinst com 2 Following the procedure given in the Register Writes section write 00000000 00000000 to the Configuration Register of the SCXI 1121 in Slot 2 This step resets the module including the clearing of the AB0EN bit bit 0 Notice that a complete reset of this module is not necessary but is used for simplicity 3 Following the procedure given in the Register Writes section write 100XXX00 00001111 to the Configuration Register of the SCXI 1121 in Slot 4 4 Following the procedure given in the Register Writes section write 010XXX01 00001111 to the Configuration Register of the SCXI 1121 in Slot 1 5 Following the procedure given in the Register Writes section write 010XXX11 00001111 to the Configuration Register of the SCXI 1121 in Slot 3 Notice that after Channel 3 the SCXI 1121 will wrap around to Channel 0 6 Follow the steps given in the section earlier in this chapter 3 Programming the Slot 0 Hardscan Circuitry where step 3 Write the Slot 0 scan list to the FIFO consists of the following a Write 00000000
41. to the Slot Select Register b Clear SERCLK to 0 c Set SERCLK to 1 This rising edge clocks the data If you are using an MIO 16 board writing to the EXTSTROBE register will pulse EXTSTROBE low and then high accomplishing steps 3b and 3c 4 Set SLOT0SEL to 1 This will assert the SS line of the module whose slot number was written to Slot 0 If you are using multiple chassis the appropriate slot in the chassis whose address corresponds to the written chassis number will be selected automatically When no communications are taking place between the data acquisition board and any modules write zero to the Slot Select Register to ensure that no accidental writes occur 5 If you are writing to a Configuration Register clear DAQD A to 0 this indicates data will be written to the Configuration Register If you are writing to the HSCR or FIFO Register leave DAQD A high 6 For each bit to be written to the Configuration Register a Establish the desired SERDATIN level corresponding to this bit b Clear SERCLK to 0 c Set SERCLK to 1 clock the data If you are using an MIO 16 board writing to the EXTSTROBE register will pulse EXTSTROBE low and then high accomplishing steps 6b and 6c 7 Pull SLOT0SEL low to deassert the SS line latch the data into the Configuration Register and establish conditions for writing a new slot select number to the Slot 0 Slot Select Register 8 If you are not selec
42. www natinst com SCXI 1351 One Slot Cable Extender The SCXI 1351 cable extender is a miniature SCXI 1340 cable assembly Instead of connecting to an MIO board 1 m away the SCXI 1351 female rear connector connects to the male breakout connector of a module that must be in the rear connector space of the slot to the left The SCXI 1351 has a female mounting bracket connector that mates with the rear signal connector of a module and also has a male breakout connector on the ribbon cable for connecting to a feedthrough panel or more cable extenders SCXI 1351 Installation Follow these steps to install the SCXI 1351 1 Make sure that the computer and the SCXI chassis are turned off 2 Install the SCXI module in the chassis 3 Connect the rear connector of the cable extender to the breakout connector in the adjacent slot This attachment is similar to Step 3 in the SCXI 1180 Installation section as shown in Figure E 2 4 Plug the mounting bracket connector to the module rear signal connector Make sure the alignment tab on the bracket enters the upper board guide of the chassis 5 Screw the mounting bracket to the threaded strips in the rear of the chassis Check the installation SCXI 1350 Multichassis Adapter You use the SCXI 1350 multichassis adapter to connect an additional SCXI 1001 chassis to the MIO 16 board Using several SCXI 1350s you can connect up to eight chassis to a single MIO board The SCXI 1350 consis
43. 121 General Parts Locator Diagram F 2 Figure F 3 Revision A and B SCXI 1121 Detailed Parts Locator Diagram F 3 Tables Table 2 1 Digital Signal Connections Jumper Settings 2 6 Table 2 2 Jumper W33 Settings 2 8 Table 2 3 Gain Jumper Allocation 2 9 Table 2 4 Gain Jumper Positions 2 9 Table 2 5 Filter Jumper Allocation 2 10 Table 2 6 Voltage and Current Mode Excitation Jumper Setup 2 11 Table 2 7 Maximum Load per Excitation Channel 2 12 Table 2 8 Excitation Level Jumper Selection 2 12 Table 2 9 Completion Network Jumpers 2 14 Table 2 10 Trimmer Potentiometer and Corresponding Channel 2 27 Table 2 11 Nulling Resistors and Corresponding Channel 2 27 Table 2 12 Jumper Settings of the Nulling Circuits 2 29 Table 2 13 Jumper Settings on the SCXI 1320 Terminal Block 2 3
44. 1344 Lab PC cable assembly E 5 problem solving and diagnostic resources online G 1 programming 5 1 to 5 17 notation 5 1 register writes 5 2 to 5 4 initialization 5 4 register selection and write procedure 5 2 to 5 3 SCXI 1121 rear signal connector equivalences table 5 2 scanning measurements 5 7 to 5 15 acquisition enable triggering and servicing 5 14 to 5 15 Counter 1 and SCANDIV 5 9 to 5 10 data acquisition board setup 5 7 to 5 9 examples 5 15 to 5 17 module programming 5 10 to 5 13 multiple chassis scanning 5 12 to 5 13 multiple module multiplexed scanning 5 12 single module multiplexed scanning indirect 5 11 to 5 12 single module parallel scanning 5 10 Slot 0 hardscan circuitry 5 13 to 5 14 single channel measurements 5 4 to 5 6 direct measurements 5 4 to 5 5 indirect measurements 5 5 to 5 6 multiplexed output 5 4 to 5 5 from other modules 5 5 parallel output 5 4 from SCXI 1121 via another module 5 5 5 6 programming languages SCXI 1121 support for 1 2 to 1 3 R RD bit 4 7 rear signal connector 2 37 to 2 46 analog output 2 39 communication signals 2 42 to 2 46 digital I O 2 40 to 2 41 pin assignments figure 2 37 B 1 SCXIbus to SCXI 1121 to DAQ board pin equivalences table 2 41 signal descriptions table 2 38 B 2 timing requirements and communication protocol 2 42 reference mode selection jumper settings for 2 6 to 2 7 register writes 5 2 to 5 4 Configuration Re
45. 3 Table 2 14 Jumper Settings on the SCXI 1328 Terminal Block 2 34 Table 2 15 Jumper Settings on the SCXI 1321 Terminal Block 2 34 Table 2 16 SCXIbus to SCXI 1121 Rear Signal Connector to Data Acquisition Board Pin Equivalences 2 42 Table 3 1 SCXIbus Equivalents for the Rear Signal Connector 3 5 Table 3 2 Calibration Potentiometer Reference Designators 3 14 Table 5 1 SCXI 1121 Rear Signal Connector Pin Equivalences 5 2 Table E 1 SCXI 1121 and MIO 16 Pinout Equivalences E 2 Table E 2 SCXI 1341 and SCXI 1344 Pin Translations E 5 Table E 3 SCXI 1342 Pin Translations E 7 Table E 4 SCXI 1343 Pin Connections E 14 National Instruments Corporation xi SCXI 1121 User Manual About This Manual This manual describes the electrical and mechanical aspects of the SCXI 1121 and contains information concerning its operation and programming The SCXI 1121 is a member of the National Instruments Signal Conditioning eXtensions for Instrumentation SCXI Series for the National Instruments data acquisition plug in boards This board is designed for signal cond
46. 6 MOSI SERDATIN ADIO0 PB4 DOUT4 D A DAQD A ADIO1 PB5 DOUT5 INTR SLOT0SEL ADIO2 PB6 DOUT6 SPICLK SERCLK EXTSTROBE PB7 DOUT7 MISO SERDATOUT BDIO0 PC1 DIN6 Chapter 2 Configuration and Installation SCXI 1121 User Manual 2 42 www natinst com Timing Requirements and Communication Protocol Timing Signal The data acquisition timing signal is SCANCLK SCANCLK is used to increment MUXCOUNTER on its rising edge Figure 2 15 shows the timing requirements of the SCANCLK signal These requirements will ensure that SCANCLK is properly transmitted over TRIG0 Figure 2 15 SCANCLK Timing Requirements For output selection time specifications refer to Appendix A Specifications Communication Signals This section describes the methods for communicating on the Serial Peripheral Interface SPI bus and their timing requirements The communication signals are SERDATIN DAQD A SLOT0SEL SERDATOUT and SERCLK Furthermore SS is produced by Slot 0 according to data acquisition board programming and SS timing relationships will also be discussed For information on the Slot 0 Slot Select Register consult Chapter 4 Register Descriptions The data acquisition board determines to which slot it will talk by writing a slot select number to Slot 0 In the case of an SCXI 1001 chassis this write also determines to which chassis the data acquisition board will talk Writing a slot select number is also used in
47. 7 and 43 constitute the digital I O lines of the rear signal connector They are divided into three categories the digital input signals the digital output signals and the digital timing signals The digital input signals are pins 24 25 27 29 33 and 37 The data acquisition board uses these pins to configure an SCXI module that is under data acquisition board control Each digital line emulates the SCXIbus communication signals as follows Pin 25 is SERDATIN and is equivalent to the SCXIbus MOSI serial data input line Pin 27 is DAQD A and is equivalent to the SCXIbus D A line It indicates to the module whether the incoming serial stream on SERDATIN is data DAQD A 0 or address DAQD A 1 information Pin 29 is SLOT0SEL and is equivalent to the SCXIbus INTR line It indicates whether the data on the SERDATIN line is being sent to Slot 0 SLOT0SEL 0 or to a module SLOT0SEL 1 Pins 24 and 33 are the digital ground references for the data acquisition board digital signals and are tied to the module digital ground Pin 37 is SERCLK and is equivalent to the SCXIbus SPICLK line and is used to clock the serial data on the SERDATIN line into the module registers The digital output signal is pin 26 Pin 26 is SERDATOUT and is equivalent to SCXIbus MISO when jumper W38 is in position 1 The digital input and output signals of the SCXI 1121 match the digital I O lines of the MIO 16
48. 7 in lb Connections including power signals to ground and vice versa that exceed any of the maximum signal ratings on the SCXI device can create a shock or fire hazard or can damage any or all of the boards connected to the SCXI chassis the host computer and the SCXI device National Instruments is not liable for any damages or injuries resulting from incorrect signal connections If high voltages 30 Vrms and 42 4 V peak or 60 VDC are present you must connect a safety earth ground wire to the terminal block safety ground solder lug This complies with safety agency requirements and protects against electric shock when the terminal block is not connected to the chassis To connect the safety earth ground to the safety ground solder lug run an earth ground wire in the cable from the signal source to the terminal block National Instruments is not liable for any damages or injuries resulting from inadequate safety earth ground connections Do not loosen or re orient the safety ground solder lug hardware when connecting the safety ground wire To do so reduces the safety isolation between the high voltage and safety ground Clean devices and terminal blocks by brushing off light dust with a soft nonmetallic brush Remove other contaminants with deionized water and a stiff nonmetallic brush The unit must be completely dry and free from contaminants before returning to service Use only National Instruments TBX Series cable assemblies wit
49. 9 to 5 10 data acquisition board setup 5 7 to 5 9 examples 5 15 to 5 17 module programming 5 10 to 5 13 multiple chassis scanning 5 12 to 5 13 multiple module multiplexed scanning 5 12 single module multiplexed scanning 5 11 to 5 12 single module parallel scanning 5 10 Slot 0 hardscan circuitry 5 13 to 5 14 scanning modes 3 17 to 3 20 analog output circuitry 3 15 multiple chassis scanning 3 20 multiple module multiplexed scanning 3 19 multiplexed scanning 3 17 to 3 18 single module multiplexed scanning 3 18 to 3 19 single module parallel scanning 3 17 SCXI 1121 See also configuration installation theory of operation block diagram 3 1 custom cables 1 5 kit contents 1 2 major components 3 2 optional equipment table 1 4 optional software 1 2 to 1 3 overview 1 1 parts locator diagrams detailed figure 2 2 general figure 2 1 Revision A and B parts locator diagram F 2 to F 3 photograph F 1 unpacking 1 6 SCXI 1121 cabling SCXI 1180 feedthrough panel E 8 to E 10 SCXI 1302 50 pin terminal block E 10 to E 11 SCXI 1340 cable assembly E 1 to E 4 SCXI 1341 Lab NB Lab PC or Lab PC cable assembly E 4 to E 6 SCXI 1342 PC LPM 16 cable assembly E 6 to E 8 Index National Instruments Corporation Index 9 SCXI 1121 User Manual SCXI 1343 rear screw terminal adapter E 14 to E 16 SCXI 1344 Lab PC cable assembly E 4 to E 6 SCXI 1350 multichassis adapter E 12 to E 13 SCXI 1351 one slot cab
50. A12 B12 A13 B13 A14 B14 A15 B15 A16 B16 A17 B17 A18 B18 A19 B19 A20 B20 A21 B21 A22 B22 A23 B23 A24 B24 D1 C1 D2 C2 D3 C3 D4 C4 D5 C5 D6 C6 D7 C7 D8 C8 D9 C9 D10 C10 D11 C11 D12 C12 D13 C13 D14 C14 D15 C15 D16 C16 D17 C17 D18 C18 D19 C19 D20 C20 D21 C21 D22 C22 D23 C23 D24 C24 GUARD GUARD GUARD AB0 GUARD GUARD GUARD GUARD GUARD GUARD RESET MISO V V CHSGND CHSGND V V 5 V SPICLK TRIG0 SS GUARD GUARD GUARD GUARD GUARD GUARD GUARD GUARD AB0 CHSGND CHSGND CHSGND CHSGND RSVD D A INTR V V V V MOSI 5 V SCANCON CHSGND CHSGND CHSGND GUARD Chapter 3 Theory of Operation SCXI 1121 User Manual 3 4 www natinst com SCXIbus Connector Signal Descriptions Pin Signal Name Description A1 B1 C1 D1 A2 D2 A3 B3 C3 D3 A4 D4 A5 B5 C5 D5 A6 D6 GUARD Guard Shields and guards the analog bus lines from noise B2 AB0 Analog Bus 0 Positive analog bus 0 line Used to multiplex several modules to one analog signal C2 AB0 Analog Bus 0 Negative analog bus 0 line Used to multiplex several modules to one analog signal C13 C17 A21 B21 C21 D21 CHSGND Chassis Ground Digital and analog ground reference C18 RSVD Reserved A19 RESET Reset When pulled low reinitializes the module to its power up state Totem pole Input B19 MI
51. ABLY PRUDENT STEPS TO PROTECT AGAINST SYSTEM FAILURES INCLUDING BUT NOT LIMITED TO BACK UP OR SHUT DOWN MECHANISMS BECAUSE EACH END USER SYSTEM IS CUSTOMIZED AND DIFFERS FROM NATIONAL INSTRUMENTS TESTING PLATFORMS AND BECAUSE A USER OR APPLICATION DESIGNER MAY USE NATIONAL INSTRUMENTS PRODUCTS IN COMBINATION WITH OTHER PRODUCTS IN A MANNER NOT EVALUATED OR CONTEMPLATED BY NATIONAL INSTRUMENTS THE USER OR APPLICATION DESIGNER IS ULTIMATELY RESPONSIBLE FOR VERIFYING AND VALIDATING THE SUITABILITY OF NATIONAL INSTRUMENTS PRODUCTS WHENEVER NATIONAL INSTRUMENTS PRODUCTS ARE INCORPORATED IN A SYSTEM OR APPLICATION INCLUDING WITHOUT LIMITATION THE APPROPRIATE DESIGN PROCESS AND SAFETY LEVEL OF SUCH SYSTEM OR APPLICATION National Instruments Corporation v SCXI 1121 User Manual Contents About This Manual Conventions xi Related Documentation xii Chapter 1 Introduction What Your Kit Should Contain 1 2 Optional Software 1 2 Optional Equipment 1 4 Custo
52. CXIbus provides analog power 18 5 VDC that is regulated on the SCXI 1121 to 15 VDC a guard an analog bus AB0 and a chassis ground CHSGND AB0 buses the SCXI 1121 output to other modules or receives outputs from other modules via the SCXIbus Refer to the Calibration section later in this chapter for more information The guard guards the analog bus and can be connected via jumper W33 to the analog ground reference or can be left floating a connection can be made by another board The data acquisition board analog input and timing is the interface between the SCXI 1121 output and the data acquisition board This is fully described in the following section Analog Input Channels Figure 3 5 is a diagram of the analog input block Chapter 3 Theory of Operation National Instruments Corporation 3 9 SCXI 1121 User Manual Figure 3 5 Analog Input Block Diagram Input Channel 1 Input Channel 2 Input Channel 3 MTEMP DTEMP Input Channel 0 LPF I To Output Stage LPF LPF To Output Stage LPF To Output Stage LPF To Output Stage I EX0 EX1 I I EX2 EX3 LPF LPF LPF Chapter 3 Theory of Operation SCXI 1121 User Manual 3 10 www natinst com The analog input consists of four isolated single ended noninverting amplifiers I
53. DIN C female connector and shell assembly is available in a kit listed in the Optional Equipment section in Chapter 1 Introduction The connector has eyelet ends for easy hook and solder wire connection With this kit you can build your own signal cable to connect to the SCXI 1121 inputs After you have built the cable the shell covers and protects the connector Perform the following steps to assemble and mount the connector and shell assembly to your SCXI module 1 Refer to Figure 2 8 Assembling and Mounting the SCXI 1330 Connector and Shell Assembly and the diagram included with your SCXI 1330 kit to build the connector and shell assembly 2 Turn off the computer that contains your DAQ board or disconnect the board from your SCXI chassis Chapter 2 Configuration and Installation National Instruments Corporation 2 23 SCXI 1121 User Manual 3 Turn off your SCXI chassis 4 Slide the selected module out of the SCXI chassis 5 Remove the module cover 6 Place one jack screw on the SCXI 1121 as indicated in Figure 2 8 7 While holding the jack screw in place insert the lock washer and then the nut Notice that you might need long nose pliers to insert the washer and nut 8 Tighten the nut by holding it firmly and rotating the jack screw 9 Repeat steps 6 through 8 for the second jack screw 10 Replace the module cover and tighten the grounding screw 11 Slide the module back in place 12 Connect t
54. Diagram National Instruments Corporation G 1 SCXI 1121 User Manual G Technical Support Resources This appendix describes the comprehensive resources available to you in the Technical Support section of the National Instruments Web site and provides technical support telephone numbers for you to use if you have trouble connecting to our Web site or if you do not have internet access NI Web Support To provide you with immediate answers and solutions 24 hours a day 365 days a year National Instruments maintains extensive online technical support resources They are available to you at no cost are updated daily and can be found in the Technical Support section of our Web site at www natinst com support Online Problem Solving and Diagnostic Resources KnowledgeBase A searchable database containing thousands of frequently asked questions FAQs and their corresponding answers or solutions including special sections devoted to our newest products The database is updated daily in response to new customer experiences and feedback Troubleshooting Wizards Step by step guides lead you through common problems and answer questions about our entire product line Wizards include screen shots that illustrate the steps being described and provide detailed information ranging from simple getting started instructions to advanced topics Product Manuals A comprehensive searchable library of the latest editions of Nat
55. Four Isolated Floating Single Ended Inputs SCXI 1000 or SCXI 1001 Chassis SLOT X SCXI 1121 Chapter 3 Theory of Operation National Instruments Corporation 3 19 SCXI 1121 User Manual Figure 3 9 Single Module Multiplexed Scanning Indirect Multiple Module Multiplexed Scanning In this mode all the modules tie into Analog Bus 0 and SCANCON enables the output of their amplifiers The module that is directly cabled to the data acquisition board sends SCANCLK onto TRIG0 for the other modules and Slot 0 as illustrated in Figure 3 10 The scan list in Slot 0 is programmed with the sequence of modules and the number of samples per entry Figure 3 10 Multiple Module Multiplexed Scanning Cable Assembly Data Acquisition Board Analog Input Timing Output Other Module Analog Bus 0 SCANCON X TRIG0 SCANCLK MCH0 SCXI 1000 or SCXI 1001 Chassis SLOT X SLOT 0 SCXI 1121 SCANCLK MCH0 Cable Assembly Data Acquisition Board Analog Input Timing Output SLOT A SLOT B SLOT 0 SLOT X TRIG0 SCANCON A SCANCON B SCANCON X SCXI 1000 or SCXI 1001 Chassis Analog Bus 0 SCXI Module SCXI Module SCXI Module Chapter 3 Theory of Operation SCXI 1121 User Manual 3 20 www natinst com Multiple Chassis Scanning In this mode you attach each SCXI 1001 chassis to a daisy chain of cable assemblies and multichassis adapter boards as illustrated in Figure 3 11 You program each ch
56. G 2 NI DAQ software 1 2 for Macintosh 1 3 notation for programming 5 1 nulling circuitry SCXI 1321 terminal block 2 25 to 2 27 formula for nulling range 2 26 to 2 27 jumper settings table 2 28 nulling resistors and corresponding channel table 2 26 trimmer potentiometer and corresponding channel table 2 25 O offset null adjust in calibration 3 12 to 3 13 offset null terminal block See SCXI 1321 terminal block ONCE bit 4 7 online problem solving and diagnostic resources G 1 operation of SCXI 1121 See theory of operation optional equipment table 1 4 optional software 1 2 to 1 3 OUTREF signal table 2 38 B 2 P parallel output single channel measurements 5 4 parallel scanning single module description 3 17 programming 5 10 Parallel Output mode 3 16 parts locator diagrams Revision A and B detailed F 3 general F 2 SCXI 1121 detailed figure 2 2 general figure 2 1 SCXI 1320 terminal block 2 34 SCXI 1321 terminal block 2 36 SCXI 1328 terminal block 2 35 physical specifications A 4 pin assignments front connector figure 2 17 D 2 rear signal connector figure 2 37 B 1 SCXI 1343 Rear Screw Terminal Adapter table E 14 to E 16 SCXIbus connector figure C 2 pin translations table SCXI 1341 Lab NB Lab PC or Lab PC cable assembly E 5 SCXI 1342 PC LPM 16 cable assembly E 6 to E 7 Index National Instruments Corporation Index 7 SCXI 1121 User Manual SCXI
57. IG0 backplane signal If CLKOUTEN is set to 1 SCANCLK is transmitted on TRIG0 If CLKOUTEN is cleared to 0 SCANCLK is not transmitted on TRIG0 14 CLKSELECT Scanclock Select This bit determines whether the SCXI 1121 uses SCANCLK or the inverted form of TRIG0 to clock the MUXCOUNTER for the purpose of scanning through the analog channels If CLKSELECT is cleared to 0 SCANCLK is used to clock MUXCOUNTER If CLKSELECT is set to 1 TRIG0 is used as the source to clock MUXCOUNTER 13 SCAL Shunt Calibrate This bit determines whether the shunt calibration switches on the SCXI 1321 are closed or open If SCAL is cleared to 0 the switches are open If SCAL is set to 1 the shunt calibration switches on the SCXI 1321 are closed and an RSCAL is placed in parallel with the bridge between EX and CH on all four channels 12 10 7 6 X Don t care bits 15 14 13 12 11 10 9 8 CLKOUTEN CLKSELECT SCAL X X X CHAN1 CHAN0 7 6 5 4 3 2 1 0 X X RTEMP RSVD SCANCLKEN SCANCONEN AB0EN FOUTEN Chapter 4 Register Descriptions SCXI 1121 User Manual 4 4 www natinst com 9 8 CHAN lt 1 0 gt Channel Select These bits determine the channel number zero to three that is loaded into the MUXCOUNTER to determine the analog channel to be read during a single read or the starting channel on the module for a scanned data acquisition CHAN1 is the MSB 5 RTEMP Read Temperature This bit determines whether the
58. Index 4 www natinst com F FIFO Register description 4 9 register writes 5 2 to 5 4 filter jumpers allocation table 2 9 description 2 9 fixed jumpers 2 2 floating signal connections AC coupled figure 2 21 referenced to chassis ground figure 2 20 FOUTEN bit 4 5 front connector 2 16 to 2 36 analog input channels 2 20 to 2 22 connector and shell assembly 2 22 to 2 24 excitation channels 2 22 pin assignments figure 2 17 D 2 SCXI 1320 SCXI 1328 and SCXI 1321 terminal blocks 2 24 to 2 36 signal descriptions table 2 18 to 2 19 D 3 to D 4 temperature sensor connection 2 22 FRT bit 4 7 G gain jumpers allocation table 2 8 positions table 2 8 grounding jumper settings for 2 6 to 2 7 ground referenced signal connections with high common mode voltage figure 2 20 referenced to chassis ground figure 2 20 GUARD signal table 3 4 C 3 H half bridge completion completion network jumpers table 2 12 to 2 13 using internal half bridge completion 2 12 Hardscan Control Register HSCR description 4 7 to 4 8 register writes 5 2 to 5 4 hardware installation 2 14 HSRS bit 4 7 I indirect measurements single channel 5 5 to 5 6 from other modules 5 5 from SCXI 1121 via another module 5 55 6 indirect multiplexed scanning single module 5 11 to 5 12 channel scanning from other modules 5 11 channel scanning from SCXI 1121 via another module 5 11 to 5 12 initialization o
59. LKEN scan clock enable bit SCANCON scanning control signal SCANCONEN scan control enable bit SCXI Signal Conditioning eXtensions for Instrumentation bus SDK software developer s kit sec seconds SERCLK serial clock signal SERDATIN serial data in signal SERDATOUT serial data out signal SL slot bit SLOT0SEL slot 0 select signal SPI serial peripheral interface SPICLK serial peripheral interface clock signal SS slot select signal T tempco temperature coefficient TRIG0 trigger 0 signal Glossary National Instruments Corporation Glossary 7 SCXI 1121 User Manual U UL Underwriters Laboratory V V volts V positive analog supply signal V negative analog supply signal VDC volts direct current VIH volts input high VIL volts input low VOH volts output high VOL volts output low Vrms volts root mean square W W watts National Instruments Corporation Index 1 SCXI 1121 User Manual Index Numbers 5 V signal front connector table 2 18 D 3 SCXIbus connector table 3 4 A AB0 signal table 3 4 C 3 AB0 signal table 3 4 C 3 AB0EN bit 4 4 AC coupled signal connections external resistor required 2 21 floating figure 2 21 referenced to chassis ground figure 2 20 acquisition enable programming 5 14 to 5 15 analog and timing circuitry 3 8 to 3 16 analog input channels 3 8 to 3 11 analog output circuitry 3 15 t
60. MCH0 In the Single Channel Read mode the MUXCOUNTER is loaded with the desired channel number In the Scanning mode the counter is loaded with the first channel to be read During the scan the counter is clocked by SCANCLK from the data acquisition board or TRIG0 from the SCXIbus depending on the state of the CLKSELECT bit in the Configuration Register During scanning operations the MUXCOUNTER is reloaded with the channel value stored AB0 Switch Buffer MCH0 Output Mux Channel 0 Channel 1 Channel 2 Channel 3 MCH0 MCH1 From Channel 1 From Channel 2 MCH1 From Channel 3 MCH2 MCH2 MCH3 MCH3 DTEMP MCH4 MCH4 MTEMP Analog Reference SCXIbus Rear Signal Connector Output Stage Control Output Stage and Hardware Scan Control Chapter 3 Theory of Operation SCXI 1121 User Manual 3 16 www natinst com in the Configuration Register when SCANCON is high inactive and will count upwards on each rising clock edge when SCANCON is low active In the Parallel Output Mode the MUXCOUNTER is disabled and its output indicates binary 00 hence amplifier channel 0 is selected at the output multiplexer and is connected to MCH0 The three other channels are hardwired to MCH1 through MCH3 on the rear signal connector The output multiplexer multiplexes all four amplifier outputs and the temperature sensor reading provided on the MTEMP line To read the temperature sensor when
61. Mounting Bracket Mounting Bracket Connector Male Breakout Connector Step 3 Step 4 Step 4 Step 5 Appendix E SCXI 1121 Cabling National Instruments Corporation E 5 SCXI 1121 User Manual jumper W1 Table E 2 lists the SCXI 1341 and SCXI 1344 pin translations Note If you are using the Lab PC configure the board for single ended inputs Table E 2 SCXI 1341 and SCXI 1344 Pin Translations Lab Board Pin Lab Board Signal SCXI 1121 Pin SCXI 1121 Signal 1 ACH0 3 MCH0 2 ACH1 5 MCH1 3 ACH2 7 MCH2 4 ACH3 9 MCH3 5 ACH4 11 MCH4 6 ACH5 13 No Connect 7 ACH6 15 No Connect 8 ACH7 17 No Connect 9 AIGND 1 2 AOGND 10 DAC0OUT 20 No Connect 11 AOGND 23 No Connect 12 DAC1OUT 21 No Connect 13 50 DGND 24 33 DIG GND 26 PB4 25 SERDATIN 27 PB5 27 DAQD A 28 PB6 29 SLOT0SEL 29 PB7 37 SERCLK 31 PC1 26 SERDATOUT 32 PC2 28 No Connect 40 EXTCONV 36 SCANCLK 43 OUTB1 46 No Connect 49 5 V 34 35 No Connect Appendix E SCXI 1121 Cabling SCXI 1121 User Manual E 6 www natinst com All other pins of the Lab board pinout are not sent to the SCXI 1121 rear signal connector SCXI 1341 and SCXI 1344 Installation Follow these steps to install the SCXI 1341 or SCXI 1344 1 Make sure that the computer and the SCXI chassis are turned off 2 Install the SCXI module in the chassis 3 Connect one end of the
62. SCXI SCXI 1121 User Manual Four Channel Isolated Universal Transducer Module for Signal Conditioning SCXI 1121 User Manual September 1999 Edition Part Number 320426C 01 Worldwide Technical Support and Product Information www natinst com National Instruments Corporate Headquarters 11500 North Mopac Expressway Austin Texas 78759 3504 USA Tel 512 794 0100 Worldwide Offices Australia 03 9879 5166 Austria 0662 45 79 90 0 Belgium 02 757 00 20 Brazil 011 284 5011 Canada Calgary 403 274 9391 Canada Ontario 905 785 0085 Canada Qu bec 514 694 8521 China 0755 3904939 Denmark 45 76 26 00 Finland 09 725 725 11 France 01 48 14 24 24 Germany 089 741 31 30 Greece 30 1 42 96 427 Hong Kong 2645 3186 India 91805275406 Israel 03 6120092 Italy 02 413091 Japan 03 5472 2970 Korea 02 596 7456 Mexico D F 5 280 7625 Mexico Monterrey 8 357 7695 Netherlands 0348 433466 Norway 32 27 73 00 Singapore 2265886 Spain Barcelona 93 582 0251 Spain Madrid 91 640 0085 Sweden 08 587 895 00 Switzerland 056 200 51 51 Taiwan 02 2377 1200 United Kingdom 01635 523545 For further support information see the Technical Support Resources appendix To comment on the documentation send e mail to techpubs natinst com Copyright 1992 1999 National Instruments Corporation All rights reserved Important Information Warranty The SCXI 1121 is warranted against defects in materials and workmanship for a period of one
63. SCXI 1121 together with the Lab LC or NB Series data acquisition boards with LabVIEW for Macintosh a software system that features interactive graphics a state of the art user interface and a powerful graphical programming language The LabVIEW Data Acquisition VI Library a series of VIs for using LabVIEW with National Instruments boards is included with LabVIEW The LabVIEW Data Acquisition VI Library is functionally equivalent to the NI DAQ software for Macintosh You can also use the SCXI 1121 combined with the NB Series data acquisition boards with NI DAQ software for Macintosh NI DAQ software for Macintosh which is shipped with all National Instruments Macintosh data acquisition boards comes with language interfaces for MPW C THINK C Pascal and Microsoft QuickBASIC Any language that uses Device Manager Toolbox calls can access NI DAQ software for Macintosh Chapter 1 Introduction SCXI 1121 User Manual 1 4 www natinst com Optional Equipment Equipment Part Number NB6 cable 0 5 m 181305 01 1 0 m 181305 10 SCXI 1320 front terminal block 776573 20 SCXI 1321 offset null and shunt calibration terminal block 776573 21 SCXI 1328 high accuracy isothermal terminal block 776573 28 SCXI 1330 32 pin connector and shell assembly 776573 30 SCXI 1340 cable assembly 776574 40 SCXI 1341 Lab NB Lab PC Lab PC cable assembly 776574 41 SCXI 1342 PC LPM 16 cable assembly 776574 42 SCXI 1343 rear screw ter
64. SGND CHSGND CHSGND GUARD Appendix C SCXIbus Connector National Instruments Corporation C 3 SCXI 1121 User Manual SCXIbus Connector Signal Descriptions Pin Signal Name Description A1 B1 C1 D1 A2 D2 A3 B3 C3 D3 A4 D4 A5 B5 C5 D5 A6 D6 GUARD Guard Shields and guards the analog bus lines from noise B2 AB0 Analog Bus 0 Positive analog bus 0 line Used to multiplex several modules to one analog signal C2 AB0 Analog Bus 0 Negative analog bus 0 line Used to multiplex several modules to one analog signal C13 C17 A21 B21 C21 D21 CHSGND Chassis Ground Digital and analog ground reference C18 RSVD Reserved A19 RESET Reset When pulled low reinitializes the module to its power up state Totem pole Input B19 MISO Master In Slave Out Transmits data from the module to the SCXIbus Open collector I O C19 D A Data Address Indicates to the module whether address information or data information is being sent to the module on MOSI Open collector I O D19 INTR Interrupt Active low Causes data that is on MOSI to be written to the Slot Select Register in Slot 0 Open collector Output A20 B20 C20 D20 V Negative Analog Supply 18 5 to 25 V A22 B22 C22 D22 V Positive Analog Supply 18 5 to 25 V A23 D23 5 V 5 VDC Source Digital power supply B23 SPICLK Serial Peripheral Interface SPI Clock Cl
65. SO Master In Slave Out Transmits data from the module to the SCXIbus Open collector I O C19 D A Data Address Indicates to the module whether address information or data information is being sent to the module on MOSI Open collector I O D19 INTR Interrupt Active low Causes data that is on MOSI to be written to the Slot Select Register in Slot 0 Open collector Output A20 B20 C20 D20 V Negative Analog Supply 18 5 to 25 V A22 B22 C22 D22 V Positive Analog Supply 18 5 to 25 V A23 D23 5 V 5 VDC Source Digital power supply B23 SPICLK Serial Peripheral Interface SPI Clock Clocks the serial data on the MOSI and MISO lines Open collector I O C23 MOSI Master Out Slave In Transmits data from the SCXIbus to the module Open collector I O Chapter 3 Theory of Operation National Instruments Corporation 3 5 SCXI 1121 User Manual MOSI MISO SPICLK and SS form a synchronous communication link that conforms with SPI using an idle high clock and second edge data latching D A INTR and RESET are additional control signals When the module is being used in an SCXI 1000 or SCXI 1001 chassis the data acquisition board via the module rear signal connector must tap into the open collector backplane signal lines as a master to write to the module The signal connections from the rear signal connector to the backplane are shown in Table 3 1 The SCXI 1121 module c
66. STROBE 43 RSVD OUT1 Table E 1 SCXI 1121 and MIO 16 Pinout Equivalences Continued Pin SCXI 1121 Rear Signal Connector MIO 16 Equivalent Appendix E SCXI 1121 Cabling SCXI 1121 User Manual E 4 www natinst com Figure E 1 SCXI 1340 Installation SCXI 1341 Lab NB Lab PC or Lab PC and SCXI 1344 Lab LC Cable Assembly The SCXI 1341 Lab NB Lab PC or Lab PC cable assembly connects a Lab NB Lab PC or Lab PC board to an SCXI 1121 module The SCXI 1344 Lab LC cable assembly connects a Lab LC board to an SCXI 1121 module The SCXI 1341 and SCXI 1344 cable assemblies consist of two pieces an adapter board and a 50 conductor ribbon cable that connects the Lab board to the rear connector of the adapter board The adapter board converts the signals from the Lab board I O connectors to a format compatible with the SCXI 1121 rear signal connector pinout at the front connector of the SCXI 1341 or SCXI 1344 The adapter board also has an additional male breakout connector that makes the unmodified Lab board signals accessible to an SCXI 1180 feedthrough panel or an SCXI 1181 breadboard module The adapter board gives the Lab boards full access to the digital control lines and analog signals but the Lab boards cannot scan channels in Multiplexed mode Leave jumper W1 in position A on the SCXI 1341 and SCXI 1344 The SCXI 1121 does not use SCXI 1121 Rear Signal Connector Rear Panel 50 Pin Female Connector to MIO 16 Board
67. Select Slot 14 in Chassis 3 12 Write XXXXX110 00000101 over MOSI 13 Toggle SLOT0SEL 14 Write XXXXX001 00000000 over MOSI 15 Toggle SLOT0SEL 16 Write XXXXX011 10000010 over MOSI 17 Select Slot 0 in Chassis 0 Chassis 1 Chassis 2 Chassis 3 Entry Slot Number Count Entry Slot Number Count Entry Slot Number Count 1 4 4 1 13 4 1 13 6 2 13 6 2 11 2 2 3 1 3 13 4 3 8 3 National Instruments Corporation A 1 SCXI 1121 User Manual A Specifications This appendix lists the specifications for the SCXI 1121 These are typical at 25 C unless otherwise stated The operating temperature range is 0 to 50 C Analog Input Gain jumper selectable 1 2 5 10 20 50 100 200 500 1 000 2 000 Output range 5 V Number of channels 4 Gain accuracy1 0 15 of full scale Offset voltage Input 6 V Output 3 mV Stability versus ambient temperature Input offset drift 0 2 V C Output offset drift 200 V C Gain drift 20 ppm C Input bias current 80 pA Input resistance Normal
68. WILL NOT BE LIABLE FOR DAMAGES RESULTING FROM LOSS OF DATA PROFITS USE OF PRODUCTS OR INCIDENTAL OR CONSEQUENTIAL DAMAGES EVEN IF ADVISED OF THE POSSIBILITY THEREOF This limitation of the liability of National Instruments will apply regardless of the form of action whether in contract or tort including negligence Any action against National Instruments must be brought within one year after the cause of action accrues National Instruments shall not be liable for any delay in performance due to causes beyond its reasonable control The warranty provided herein does not cover damages defects malfunctions or service failures caused by owner s failure to follow the National Instruments installation operation or maintenance instructions owner s modification of the product owner s abuse misuse or negligent acts and power failure or surges fire flood accident actions of third parties or other events outside reasonable control Copyright Under the copyright laws this publication may not be reproduced or transmitted in any form electronic or mechanical including photocopying recording storing in an information retrieval system or translating in whole or in part without the prior written consent of National Instruments Corporation Trademarks LabVIEW natinst com National Instruments NI DAQ RTSI and SCXI are trademarks of National Instruments Corporation Product and company names mentioned herein are trade
69. Wheatstone bridges as well as a shunt resistor for strain gauge shunt calibration This terminal block works especially well with bridge type transducers such as strain gauges The SCXI 1321 can also easily accommodate thermocouples RTDs thermistors millivolt sources volt sources and current loop receivers SCXI 1321 Nulling Circuitry The nulling circuitry operates with full bridge half bridge quarter bridge and strain gauge configurations Each channel has its own nulling circuitry and its own trimming potentiometer as listed in Table 2 10 To null the static offset voltage of the bridge use the following procedure 1 Configure your bridge to the selected channel 2 Select and read the channel output 3 While monitoring the output rotate the trimmer wiper with a flathead screwdriver until you reach 0 V You have nulled your bridge and are ready for a measurement The nulling range for your terminal block is 2 5 mV assuming that you have a 120 strain gauge and 3 333 V excitation voltage You can change this range by replacing the nulling resistor with a resistor of another value Each channel has an independent nulling resistor You can therefore mix your ranges to accommodate each channel requirement Table 2 11 lists the nulling resistors and their corresponding channels Table 2 10 Trimmer Potentiometer and Corresponding Channel Channel Number Trimmer Potentiometer 0 R1 1 R2 2 R14 3 R15 C
70. XI 1121 User Manual Lab NB User Manual Program the sample interval counter Counter A0 Service the data acquisition operation Scanning Examples The following examples are intended to aid your understanding of module and Slot 0 programming It will be helpful to refer to the bit descriptions for the Configuration Register and the FIFO Register at the beginning of Chapter 4 Register Descriptions Example 1 You want to scan in Multiplexed mode channels 1 through 3 on an SCXI 1121 in Slot 1 of an SCXI 1000 chassis The SCXI 1121 is directly cabled to a data acquisition board The programming steps are as follows 1 Program your data acquisition board as described in the 1 Data Acquisition Board Setup Programming section of this chapter 2 Following the procedure given in the Register Writes section write 10000001 00001101 to the Configuration Register of the SCXI 1121 in Slot 1 3 Follow the steps outlined in the section earlier in this chapter 3 Programming the Slot 0 Hardscan Circuitry where step 3 Write the Slot 0 scan list to the FIFO consists of the following Write 00000000 00000010 to the FIFO Register This corresponds to Slot 1 for three samples 4 Follow the procedure given in the section 4 Acquisition Enable Triggering and Servicing earlier in this chapter Example 2 An SCXI 1000 chassis has four SCXI 1121s in Slots 1 2 3 and 4 The SCXI 1121 in Slot 4 is cabled to
71. adjust 3 13 to 3 14 offset null adjust 3 11 potentiometer reference designators table 3 14 CGND signal table 2 18 D 3 CH0 signal table 2 19 D 4 CH0 signal table 2 19 D 4 CH1 signal table 2 19 D 4 CH1 signal table 2 19 D 4 CH2 signal table 2 19 D 4 CH2 signal table 2 19 D 4 CH3 signal table 2 18 D 3 CH3 signal table 2 18 D 3 CHAN lt 1 0 gt bits 4 4 CHS lt 4 0 gt bits 4 6 CHSGND signal table 3 4 C 3 CLKEN bit 4 8 CLKOUTEN bit 4 3 CLKSELECT bit 4 3 CNT lt 6 0 gt bits 4 9 cold junction sensor specifications A 3 to A 4 communication signals 2 42 to 2 47 overview 2 42 reading from Module ID Register 2 45 to 2 46 serial data timing diagram 2 44 slot select timing diagram 2 43 timing requirements for SERCLK and SERDATIN signals figure 2 44 writing 16 bit slot select number to Slot 0 2 43 writing to Configuration Register 2 44 to 2 45 completion network jumpers table 2 12 to 2 13 configuration analog 2 6 to 2 13 excitation jumpers 2 9 to 2 13 filter jumpers 2 9 gain jumpers 2 8 grounding shielding and reference mode selection 2 6 to 2 7 input channel jumpers 2 8 to 2 13 jumper W33 2 6 to 2 7 digital signal connections jumper settings figure 2 5 to 2 6 jumper W32 2 4 jumper W38 2 4 jumper W44 2 3 to 2 4 using jumpers W32 and W38 2 4 to 2 5 excitation jumpers 2 9 to 2 13 current and voltage jumpers 2 9 to 2 10 excitation level 2 10 to
72. another ribbon cable or cable assembly to the chassis extender connector 6 Plug the adapter board front connector to the module rear signal connector Make sure a corner of the adapter board enters the upper board guide of the chassis 7 Screw the rear panel to the threaded strips in the rear of the chassis 8 Connect the cable assembly to the desired module in the second chassis or if you are using more than two chassis connect the loose end of the ribbon cable to the rear connector of the second SCXI 1350 and install the adapter board 9 Continue until all chassis are connected For N chassis you will need N ribbon cables and N multichassis adapters Appendix E SCXI 1121 Cabling SCXI 1121 User Manual E 14 www natinst com SCXI 1343 Rear Screw Terminal Adapter You use the SCXI 1343 universal adapter to adapt custom wiring to the SCXI 1121 The SCXI 1343 has screw terminals for the analog output connections and solder pads for the rest of the signals A strain relief clamp is on the outside of the rear panel Table E 4 shows the SCXI 1343 pin connections SCXI 1343 Installation Follow these steps to install the SCXI 1343 1 Insert each wire through the adapter strain relief opening 2 Make all solder connections first 3 Connect the other wires to the screw terminals 4 Tighten the strain relief screws to secure the wires 5 Plug the adapter board front connector to the module rear signal connec
73. arries the SCXIbus MISO line after buffering to the SERDATOUT signal on the rear signal connector On Revision C or later modules jumper W32 connects a pullup resistor to the SERDATOUT signal on the rear signal connector Jumper W33 configures the guard the analog output ground and enables the Pseudodifferential Reference mode Chapter 2 Configuration and Installation National Instruments Corporation 2 3 SCXI 1121 User Manual Jumpers W3 W19 W29 and W41 configure the first stage gain of input channels 0 through 3 respectively Jumpers W4 W20 W30 and W42 configure the second stage gain of input channels 0 through 3 respectively Jumpers W5 W21 W31 and W43 configure the first stage filtering of input channels 0 through 3 respectively Jumpers W6 and W7 W8 and W9 W10 and W11 and W12 and W13 configure the second stage filtering of input channels 0 through 3 respectively Jumpers W14 and W15 W22 and W23 W34 and W35 and W46 and W47 configure the voltage or current mode of operation for excitation channels 0 through 3 respectively Jumpers W16 and W26 W24 and W25 W36 and W37 and W48 and W49 configure the level of excitation for excitation channels 0 through 3 respectively Jumpers W1 and W2 W17 and W18 W27 and W28 and W39 and W40 configure the half bridge completion network for channels 0 through 3 respectively Further configuration of the board is so
74. assis separately and each chassis occupies a dedicated channel of the data acquisition board Within each chassis scanning operations act as if the other chassis are not being used with one exception You must program the Slot 0 scan list in each chassis with dummy entries of Slot 13 to fill the samples when the data acquisition board will be sampling another chassis or data acquisition board channel This will keep the chassis synchronized Notice that you can only perform multiple chassis scanning with the SCXI 1001 chassis and MIO 16 data acquisition boards See Chapter 5 Programming for more information on multiple chassis scanning See Appendix E SCXI 1121 Cabling for more information on the necessary cable accessories for multichassis scanning Figure 3 11 Multiple Chassis Scanning Multichassis Adapter Chassis 2 Chassis 1 Data Acquisition Board Timing Output Input Ch 0 Input Ch 1 Input Ch N Chassis N Multichassis Adapter Cable Assemblies Cable Assembly Multichassis Adapter Cable Assembly Chassis National Instruments Corporation 4 1 SCXI 1121 User Manual 4 Register Descriptions This chapter describes in detail the SCXI 1121 Module ID Register the Configuration Register the Slot 0 registers and multiplexer addressing Note If you plan to use a programming software package such as NI DAQ LabWindows or LabVIEW with your SCXI 1121 board you do not need to read this chapter Reg
75. bandwidth For example to achieve a gain of 100 use G1st 10 and G2nd 10 for a gain of 1 000 use G1st 50 and G2nd 20 All the amplifier input channels are overvoltage protected to 240 Vrms with power on or off The isolated amplifiers fulfill two purposes on the SCXI 1121 module They convert a small signal riding on a high common mode voltage into a single ended signal with respect to the SCXI 1121 chassis ground With this conversion the input analog signal can be extracted from a high common mode voltage or noise before being sampled and converted by the data acquisition board The isolated amplifier also amplifies and conditions an input signal which results in an increase in measurement resolution and accuracy Gtotal G1st G2nd BW GBWP G Chapter 3 Theory of Operation National Instruments Corporation 3 11 SCXI 1121 User Manual After isolation further filtering is available to increase the noise immunity of the amplifier channel It is important to note that the overall amplifier bandwidth is determined by both filtering stages so to achieve the required bandwidth both filtering sections should be set the same as indicated in Chapter 2 Configuration and Installation Excitation Output Channels In addition to the four input channels the SCXI 1121 contains four fully isolated excitation channels each corresponding to an input channel For instance input channel 0 corresponds
76. ble E 6 to E 7 SCXI 1343 rear screw terminal adapter E 14 to E 16 installation E 14 pin connections table E 14 to E 16 SCXI 1344 Lab PC cable assembly E 4 to E 6 description E 4 installation E 6 pin translations table E 5 SCXI 1350 multichassis adapter E 12 to E 13 description E 12 to E 13 installation E 13 SCXI 1351 one slot cable extender E 12 SCXIbus connector equivalences rear signal connector table 3 5 rear signal connector to DAQ board pin equivalences table 2 41 pin assignments figure 3 3 C 2 signal descriptions table 3 4 to 3 5 C 3 to C 4 Index SCXI 1121 User Manual Index 10 www natinst com SERCLK signal See also communication signals description table 2 38 B 2 register writes 5 2 to 5 3 SCXIbus to SCXI 1121 rear signal connector to DAQ board pin equivalences table 2 41 timing requirements figure 2 44 SERDATIN signal See also communication signals description table 2 38 B 2 register writes 5 2 to 5 3 SCXIbus equivalents for rear signal connector table 3 5 SCXIbus to SCXI 1121 rear signal connector to DAQ board pin equivalences table 2 41 timing requirements figure 2 44 SERDATOUT signal See also communication signals description table 2 38 B 2 SCXIbus to SCXI 1121 rear signal connector to DAQ board pin equivalences table 2 41 serial data timing diagram 2 44 servicing programming 5 14 to 5 15 shielding jumper settings for 2 6 to 2 7 shunt
77. canning 3 17 Multiplexed Scanning 3 17 Single Module Multiplexed Scanning 3 18 Multiple Module Multiplexed Scanning 3 19 Multiple Chassis Scanning 3 20 Chapter 4 Register Descriptions Register Description 4 1 Register Description Format 4 1 SCXI 1121 Registers 4 1 Slot 0 Register Descriptions 4 5 Chapter 5 Programming Programming Considerations 5 1 Notation 5 1 Register Writes 5 2 Register Selection and Write Procedure 5 2 Initialization
78. corded the jumper settings on the form in Appendix G Technical Support Resources you are ready to install the SCXI 1121 The following are general installation instructions consult the user manual or technical reference manual of your SCXI chassis for specific instructions and warnings 1 Turn off the computer that contains the data acquisition board or disconnect it from your SCXI chassis 2 Turn off the SCXI chassis Do not insert the SCXI 1121 into a chassis that is turned on 3 Insert the SCXI 1121 into the board guides Gently guide the module into the back of the slot until the connectors make good contact If a cable assembly has already been installed in the rear of the chassis the module and cable assembly must be firmly engaged however do not force the module into place 4 Screw the front mounting panel of the SCXI 1121 to the top and bottom threaded strips of your SCXI chassis 5 If this module is to be connected to an MIO 16 data acquisition board attach the connector at the metal end of the SCXI 1340 cable assembly to the rear signal connector on the SCXI 1121 module Screw the rear panel to the rear threaded strip Attach the loose end of the cable to the MIO 16 board Note For installation procedures with other SCXI accessories and data acquisition boards consult Appendix E SCXI 1121 Cabling 6 Check the installation 7 Turn on the SCXI chassis 8 Turn on the computer or reconnect it to your cha
79. ctional components of the SCXI 1121 Figure 3 1 SCXI 1121 Block Diagram SCXIbus Digital Interface and Control Timing and Analog Output Stage Front Connector Rear Signal Connector Isolated Section Nonisolated Section Input channel 0 Excitation 0 Input channel 3 Excitation 3 Temperature sensor Chapter 3 Theory of Operation SCXI 1121 User Manual 3 2 www natinst com The major components of the SCXI 1121 are as follows SCXIbus connector Digital interface Digital control circuitry Timing and analog circuitry The SCXI 1121 consists of four isolated amplifier channels with gains of 1 2 5 10 20 50 100 200 500 1 000 and 2 000 and four isolated excitation channels with voltage or current excitation The SCXI 1121 also has a digital section for automatic control of channel scanning for temperature selection and for MUXCOUNTER clock selection The theory of operation for each of these components is explained in the rest of this chapter Chapter 3 Theory of Operation National Instruments Corporation 3 3 SCXI 1121 User Manual SCXIbus Connector Figure 3 2 shows the pin assignments for the SCXIbus connector Figure 3 2 SCXIbus Connector Pin Assignment A1 B1 A2 B2 A3 B3 A4 B4 A5 B5 A6 B6 A7 B7 A8 B8 A9 B9 A10 B10 A11 B11
80. e AT MIO 64F 5 Do not continue to the part called Enable the Scanning Data Acquisition Operation You will do this after you program the modules and Slot 0 Program the Sample Counter if you are doing continuous channel scanning or Program the Scan Interval Counter if you are doing interval channel scanning in the AT MIO 16X or AT MIO 64F 5 user manual Do not continue to the part labeled Enable a Scanning Data Acquisition Operation or Enable an Interval Scanning Data Acquisition Operation You will do this after you program the modules and Slot 0 Note For multiplexed scanning with an MIO board it is important that you follow the instructions in the channel scanning sections not the single channel sections Although you may be using only one MIO board channel the channel scanning programming will ensure that the MIO board outputs SCANCLK which is needed by the SCXI 1120 and Slot 0 Clear the A D Circuitry in the Lab LC User Manual Do not continue to the part called Program the Sample Interval Counter You will do this after you program the modules and Slot 0 Clear the A D Circuitry in the Lab PC User Manual the Lab PC User Manual and the PC LPM 16 User Manual Do not continue to the part called Start and Service the Data Acquisition Operation You will do this after you program the modules and Slot 0 Clear the A D Circuitry in the Lab NB User Manual Do not continue to the part called Program the Sample In
81. e being routed to the rest of the module The channel select bits are taken directly from the shift register Complete descriptions of the register bits are given in Chapter 4 Register Descriptions Writes to the Configuration Register require the following steps 1 SS goes low enabling communication with the board 2 D A goes low indicating that the information sent on the MOSI line is data Module ID Register Configuration Register Serial Data Out Input Channel Select Output Stage Control Hardware Scan Control SCANCLK Path Control Buffered Serial Data In Buffered Digital Control Signals Chapter 3 Theory of Operation SCXI 1121 User Manual 3 8 www natinst com 3 The serial data is available on MOSI and SPICLK clocks it into the register 4 SS goes high and D A goes high indicating an end of communication This action latches the Configuration Register bits When the SCXIbus is reset all bits in the Configuration Register are cleared The Module ID Register connects to MISO on the SCXIbus The Module ID Register is an 8 bit parallel serial in serial out shift register and an SPI communication adapter The contents of the Module ID Register are written onto MISO during the first four bytes of transfer after SS has been asserted low Zeros are written to MISO thereafter until SS is released and reasserted The SCXI 1121 module ID is hex 00000002 Analog and Timing Circuitry The S
82. e module multiplexed scanning 3 19 multiplexed scanning 3 17 to 3 18 single module multiplexed scanning 3 18 to 3 19 single module parallel scanning 3 17 SCXIbus connector equivalents for rear signal connector table 3 5 pin assignments figure 3 3 signal descriptions table 3 4 to 3 5 thermistors using with SCXI 1321 terminal block 2 27 to 2 28 timing circuitry See analog and timing circuitry timing signal See SCANCLK signal TRIG0 signal table 3 5 C 4 triggering programming 5 14 to 5 15 U user configurable jumpers 2 2 to 2 3 V V signal table 3 4 C 3 V signal table 3 4 C 3 voltage and current excitation jumpers 2 9 to 2 10 Index SCXI 1121 User Manual Index 12 www natinst com W Web support from National Instruments G 1 to G 2 online problem solving and diagnostic resources G 1 software related resources G 2 Worldwide technical support G 2 Wxx jumpers See jumpers
83. e quarter bridge strain equation produces an equivalent 199 of change SCAL EX R CH EX RSCAL SCXI 1321 Rg R R CH Vchange VexcRd RSCAL Rg RSCAL Rd RSCAL Rg Vexc 2 Chapter 2 Configuration and Installation SCXI 1121 User Manual 2 30 www natinst com Terminal Block Temperature Sensor To accommodate thermocouples with the SCXI 1121 the terminal block has an onboard temperature sensor for cold junction compensation You can connect this temperature sensor in two ways You can connect the temperature sensor to the MTEMP pin C4 on the module front connector and multiplex the sensor at the output multiplexer along with the amplifier outputs This is the Multiplexed Temperature Sensor MTS mode Refer to the Configuration Register section in Chapter 4 Register Descriptions for further details You can connect the temperature sensor to a separate data acquisition channel via MCH4 pins 11 and 12 on the module rear signal connector This is the Direct Temperature Sensor DTS mode Note Use an average of a large number of samples to obtain the most accurate reading Noisy environments require more samples for greater accuracy The SCXI 1320 and SCXI 1321 temperature sensors output 10 mV C and have an accuracy of 1 C over the 0 to 55 C temperature range To determine
84. earth ground can damage the SCXI 1121 the SCXIbus and the DAQ board National Instruments is not liable for any damages or injuries resulting from such signal connections Excitation Channels Four fully isolated excitation channels are available Each excitation channel corresponds to an input channel A 250 Vrms isolation barrier exists between two corresponding channels for example between input channel 0 and excitation channel 0 In addition the excitation outputs are overvoltage protected to 250 Vrms with current foldback Warning Exceeding the overvoltage protection or isolation rating on the excitation output can damage the SCXI 1121 the SCXIbus and the DAQ board National Instruments is not liable for any damages or injuries resulting from such signal connections Temperature Sensor Connection Pins C2 and C4 are dedicated for connecting the temperature sensor to the SCXI 1121 The temperature sensor is not isolated and is referenced to chassis ground The connection is overvoltage protected to 25 VDC with power on and 15 VDC with power off Warning Exceeding the overvoltage protection on the temperature connections can damage the SCXI 1121 the SCXIbus and the DAQ board National Instruments is not liable for any damages resulting from such signal connections Connector and Shell Assembly Two types of signal connectors are available to connect the transducers to the SCXI 1121 inputs The first the SCXI 1330 32 pin
85. ector 4 Plug the adapter board front connector onto the module rear signal connector Make sure a corner of the adapter board enters the upper board guide of the chassis 5 Screw the rear panel to the threaded strips in the rear of the chassis 6 Connect the loose end of the ribbon cable to the PC LPM 16 I O connector Check the installation SCXI 1180 Feedthrough Panel The SCXI 1180 feedthrough panel provides front panel access to the signals of any data acquisition board that uses a 50 pin I O connector The SCXI 1180 consists of a front panel with a 50 pin male front panel connector that occupies one slot in the SCXI chassis and a ribbon cable with a female rear connector and a male breakout connector You can attach the rear connector to the male breakout connector of an SCXI 1340 SCXI 1341 SCXI 1342 SCXI 1344 or SCXI 1351 in the adjacent slot The breakout connector further extends the cabling scheme The front panel connector provides the feedthrough connection You can attach an SCXI 1302 terminal block to the front panel connector for simple screw terminal connections A rear filler panel that shields and protects the interior of the SCXI chassis is also included Appendix E SCXI 1121 Cabling National Instruments Corporation E 9 SCXI 1121 User Manual SCXI 1180 Installation Install the SCXI 1180 to the right of a slot that has an SCXI 1340 SCXI 1341 SCXI 1342 or SCXI 1344 cable assembly or an SCXI 1351
86. ects the temperature sensor to the SCXI 1121 MCH4 signal on the rear signal connector In both MTS and DTS modes the reference to the temperature sensor signal is the SCXI 1121 analog ground that is connected to MCH0 in the MTS mode and to MCH4 in the DTS mode Notice that MCH4 is continuously connected to the SCXI 1121 ground whereas MCH0 is switched through the output multiplexer One jumper block comprises both positions therefore you can use only one type of configuration at a time The parking position for the jumper block is in the MTEMP position the temperature sensor is disabled until the RTEMP bit in the Configuration Register selects the sensor TK 1 a b RT ln c RT ln 3 RT 50 000 VTEMPOUT 2 5 VTEMPOUT T F T C 9 5 32 Chapter 2 Configuration and Installation SCXI 1121 User Manual 2 32 www natinst com Tables 2 13 2 14 and 2 15 show the jumper settings on the SCXI 1320 SCXI 1328 and SCXI 1321 terminal blocks Table 2 13 Jumper Settings on the SCXI 1320 Terminal Block Jumper Position Description W1 MTS mode selected factory setting parking position W1 DTS mode selected Table 2 14 Jumper Settings on the SCXI 1328 Terminal Block Jumper Position Description W1 MTS mode selected
87. eir Configuration Registers Multiple Chassis Scanning To scan modules on multiple chassis you must use the SCXI 1001 The cable from the data acquisition board must bus the digital lines to one module on each chassis Additionally the cable must provide each chassis with its own analog channel The data acquisition board must be able to take several readings at a time on a given channel before accessing a new Chapter 5 Programming National Instruments Corporation 5 13 SCXI 1121 User Manual channel See the Counter 1 and SCANDIV subsection of the 1 Data Acquisition Board Setup Programming section earlier in this chapter You can use the MIO 16 boards in conjunction with the SCXI 1350 multichassis adapter for multichassis scanning For each chassis program the modules according to the appropriate mode of operation disregarding the fact that other chassis will be involved For example you want to scan thirteen modules Twelve modules are in one chassis The thirteenth is in the second chassis and is to be scanned through a fourteenth module that is cabled to the data acquisition board but is not involved in the scan Program the twelve modules in the first chassis according to the steps in the previous Multiple Module Multiplexed Scanning section and program the thirteenth and fourteenth modules according to Channel Scanning from the SCXI 1121 via Another Module earlier in this chapter 3 Programming the Slot 0 Hardscan Circu
88. el 1 is disabled W3 Nulling circuit of Channel 2 is enabled factory setting Nulling circuit of Channel 2 is disabled W4 Nulling circuit of Channel 3 is enabled factory setting Nulling circuit of Channel 3 is disabled D E D E D E D E D E D E D E D E Chapter 2 Configuration and Installation National Instruments Corporation 2 29 SCXI 1121 User Manual Figure 2 10 Shunt Circuit The shunting resistors RSCAL are socketed so that you can replace them with a resistor of another value to achieve the required changes The RSCAL resistors on your terminal block have a 301 k 1 value Assuming a quarter bridge strain gauge configuration with a gauge factor of GF 2 the equivalent strain change introduced by the RSCAL shunting resistor is 199 Determine the change as follows 1 Determine the change caused by the shunting resistor using the following formula 2 Using the appropriate strain gauge strain formula and assuming that you have no static voltage determine the equivalent strain that the RSCAL should produce For example RSCAL 301 k and a quarter bridge 120 strain gauge with a gauge factor of GF 2 and Vexc 3 333 V and R 120 produces the following result Vchange 0 3321 mV Replacing the strained voltage with Vchange in th
89. el Scanning Data Acquisition Interval Channel Scanning Data Acquisition Lab LC User Manual Programming Multiple A D Conversions with Channel Scanning Lab NB User Manual Programming Multiple A D Conversions with Channel Scanning Lab PC User Manual Programming Multiple A D Conversions with Channel Scanning Lab PC User Manual Programming Multiple A D Conversions with Channel Scanning Programming Multiple A D Conversions with Interval Scanning Programming Multiple A D Conversions in Single Channel Interval Acquisition Mode MC MIO 16 User Manual Multiple A D Conversions with Continuous Channel Scanning Round Robin Multiple A D Conversions with Interval Channel Scanning Pseudosimultaneous NB MIO 16 User Manual Programming Multiple A D Conversions with Channel Scanning NB MIO 16X User Manual Multiple A D Conversions with Continuous Channel Scanning Round Robin Multiple A D Conversions with Interval Channel Scanning Pseudosimultaneous PC LPM 16 User Manual Programming Multiple A D Conversions with Channel Scanning Chapter 5 Programming National Instruments Corporation 5 9 SCXI 1121 User Manual Follow the instructions in these sections through the part labeled as follows Clear the A D Circuitry and Reset the Mux Counter in the MIO board user manual except for the AT MIO 16X and th
90. er W38 set to position 1 Table 2 1 Digital Signal Connections Jumper Settings Jumper Description Configuration W38 Factory setting connects MISO to SERDATOUT W38 Parking position W45 Factory setting 3 2 1 3 2 1 3 2 1 Chapter 2 Configuration and Installation SCXI 1121 User Manual 2 6 www natinst com Analog Configuration The SCXI 1121 has 45 analog configuration jumpers Before starting notice that the jumper configurations for each input channel and each excitation channel are similar only the jumper numbers differ Therefore when you learn how to set up one channel pair input and excitation you can set up the other channel pairs as well Grounding Shielding and Reference Mode Selection Jumper W33 Position AB R0 connects the analog reference to the analog output ground pins 1 and 2 on the rear signal connector Select this configuration if you are using an RSE data acquisition board It is not recommended to use a differential input data acquisition board when jumper W33 is in the AB R0 position W44 Factory setting Revision A and B modules only W32 Fatory default setting connects pullup to SERDATOUT Revision C and later W32 Parking position not connected on Revision A or B modules Table 2 1 Digital Signal Connections Jumper Settings Continued Jumper Description Configuration
91. erature sensor A20 CH2 Positive Input Channel 2 This pin is connected to the input channel 2 positive input C20 CH2 Negative Input Channel 2 This pin is connected to the input channel 2 negative input A22 EGND1 Excitation Ground 1 This pin connects to the excitation ground 1 via a 51 k resistor A24 EX1 Positive Excitation Output 1 This pin is connected to the excitation channel 1 positive output C24 EX1 Negative Excitation Output 1 This pin is connected to the excitation channel 1 negative output A26 CH1 Positive Input Channel 1 This pin is connected to the input channel 1 positive input C26 CH1 Negative Input Channel 1 This pin is connected to the input channel 1 negative input A28 EGND0 Excitation Ground 0 This pin connects to the excitation ground 0 via a 51 k resistor A30 EX0 Positive Excitation Output 0 This pin is connected to the excitation channel 0 positive output C30 EX0 Negative Excitation Output 0 This pin is connected to the excitation channel 0 negative output A32 CH0 Positive Input Channel 0 This pin is connected to the input channel 0 positive input C32 CH0 Negative Input Channel 0 This pin is connected to the input channel 0 negative input Pin Signal Name Description Chapter 2 Configuration and Installation SCXI 1121 User Manual 2 20 www natinst com Analog Input Channels The positive input channels are loca
92. f registers 5 4 input channel jumpers 2 8 to 2 13 excitation jumpers 2 9 to 2 13 current and voltage jumpers 2 9 to 2 10 excitation level 2 10 to 2 11 internal half bridge completion 2 12 to 2 13 filter jumpers 2 9 gain jumpers 2 8 installation hardware installation 2 14 SCXI 1180 feedthrough panel E 9 to E 10 SCXI 1302 50 pin terminal block E 11 SCXI 1340 cable assembly E 3 to E 4 Index National Instruments Corporation Index 5 SCXI 1121 User Manual SCXI 1341 Lab NB Lab PC or Lab PC cable assembly E 6 SCXI 1342 PC LPM 16 cable assembly E 8 SCXI 1343 rear screw terminal adapter E 14 SCXI 1344 Lab PC cable assembly E 6 SCXI 1350 multichassis adapter E 13 SCXI 1351 one slot cable extender E 12 terminal blocks 2 36 unpacking SCXI 1121 1 6 internal half bridge completion 2 12 to 2 13 INTR signal description table 3 4 C 3 SCXIbus equivalents for rear signal connector table 3 5 SCXIbus to SCXI 1121 rear signal connector to DAQ board pin equivalences table 2 41 J jumpers fixed jumpers 2 2 settings for nulling circuits table 2 28 terminal block configuration 2 31 to 2 32 user configurable jumpers 2 2 to 2 3 W1 nulling circuit setting table 2 28 SCXI 1320 terminal block table 2 32 SCXI 1328 terminal block table 2 32 W2 nulling circuit setting table 2 28 W3 table 2 28 W4 table 2 28 W5 table 2 32 W32 configuration 2 4 to 2 5 description 2 4 settings tab
93. factory setting parking position W1 DTS mode selected Table 2 15 Jumper Settings on the SCXI 1321 Terminal Block Jumper Position Description W5 MTS mode selected factory setting parking position W5 DTS mode selected MTEMP DTEMP MTEMP DTEMP DTEMP MTEMP DTEMP MTEMP MTEMP DTEMP MTEMP DTEMP Chapter 2 Configuration and Installation National Instruments Corporation 2 33 SCXI 1121 User Manual Terminal Block Signal Connection Warnings The chassis GND terminals on your terminal block are for grounding high impedance sources such as a floating source 1 mA maximum Do not use these terminals as safety earth grounds If high voltages 42 Vrms are present you must connect the safety earth ground to the strain relief tab This complies with UL 1244 and fully protects against electric shock when the terminal block is not connected to the chassis To connect the safety earth ground to the strain relief tab run an earth ground wire in the cable from the signal source to the terminal block National Instruments is not liable for any damages or injuries resulting from inadequate safety earth ground connections Shock Hazard This unit should only be opened by qualified personnel aware of the dangers involved Disconnect all power before
94. ftware controlled and will be discussed later in this chapter Digital Signal Connections The SCXI 1121 has three jumpers dedicated for communication between the data acquisition board and the SCXIbus These jumpers are W32 W38 and W44 Jumper W44 Position 1 on Revision A and B modules connects after buffering SLOT0SEL to the SCXIbus INTR line This is the factory default setting and should not be changed In this setting the data acquisition board controls the SCXIbus INTR line See the Timing Requirements and Communication Protocol section later in this chapter and Chapter 5 Programming for information on the use of the INTR line See Appendix E SCXI 1121 Cabling for the pin equivalences of the SCXI 1121 rear signal connector and the data acquisition board I O connector Position 3 is reserved and should not be used This position is not explicitly marked on the module Chapter 2 Configuration and Installation SCXI 1121 User Manual 2 4 www natinst com On Revision C or later modules jumper W44 does not exist SLOT0SEL is always buffered to the INTR line Jumper W38 Position 1 connects after buffering the SCXIbus MISO line to the SERDATOUT pin of the rear signal connector In this setting along with the proper setting of W32 the data acquisition board can read the Module ID Register of the SCXI 1121 See the Timing Requirements and Communication Protocol section later in this chapter and Chapter 4 Regis
95. g the noise generated by the isolation amplifier Furthermore two filter bandwidths are available 10 kHz and 4 Hz Your SCXI 1121 is shipped in the 4 Hz configuration Always make sure to set both stages to the same bandwidth This will ensure that the required bandwidth is achieved Excitation Jumpers Current and Voltage Excitation Jumpers You can configure each excitation channel of your SCXI 1121 to either a Voltage or Current excitation mode Each channel has two jumpers for this purpose Set both jumpers in the same mode for correct operation of the excitation channel Refer to Table 2 6 for setting up your module in the mode you want Your SCXI 1121 is shipped to you in the Voltage mode Table 2 5 Filter Jumper Allocation Input Channel Number First Filter Jumper Second Filter Jumper 4 Hz Factory Setting 10 kHz 4 Hz Factory Setting 10kHz 0 W5 A W5 B W6 W7 1 W21 A W21 B W8 W9 2 W31 A W31 B W10 W11 3 W43 A W43 B W12 W13 Chapter 2 Configuration and Installation SCXI 1121 User Manual 2 10 www natinst com Excitation Level Each excitation channel of your SCXI 1121 has two different current or voltage levels You can set a given channel to one of the following level modes In the Current mode 0 150 or 0 450 mA In the Voltage mode 3 333 or 10 V It is important to notice that you should select the level of excitation according to the load you are using Table 2 7 li
96. gister digital control circuitry 3 7 to 3 8 programming 5 2 to 5 4 slot selection procedure 2 44 to 2 45 initialization 5 4 register selection and write procedure 5 2 to 5 3 SCXI 1121 rear signal connector equivalences table 5 2 registers 4 1 to 4 9 Configuration Register description 4 3 to 4 5 overview 3 7 write timing diagram 2 45 writing to 2 44 to 2 45 3 7 to 3 8 5 2 to 5 4 description format 4 1 FIFO Register description 4 9 register writes 5 2 to 5 4 Hardscan Control Register HSCR 4 7 to 4 8 Module ID Register description 4 2 overview 3 8 reading from 2 45 to 2 46 Index SCXI 1121 User Manual Index 8 www natinst com timing diagram 2 46 Slot 0 Register description 4 5 programming hardscan circuitry 5 13 to 5 14 Slot Select Register 4 6 register writes 5 2 to 5 4 RESET signal table 3 4 C 3 Revision A and B parts locator diagram detailed F 3 general F 2 photograph F 1 RTDs specifications for RTD mode A 3 using with SCXI 1321 terminal block 2 27 to 2 28 RTEMP bit 4 4 S safety specifications A 4 SCAL bit 4 3 SCAL signal table 2 18 D 3 SCANCLK signal description table 2 38 B 2 timing requirements 2 42 SCANCLKEN bit 4 4 SCANCON signal table 3 5 C 4 SCANCONEN bit 4 4 4 8 SCANDIV bit scanning measurements 5 9 to 5 10 scanning measurements programming 5 7 to 5 15 acquisition enable triggering and servicing 5 14 to 5 15 Counter 1 and SCANDIV 5
97. h high voltage TBX Series terminal blocks Front Connector Figure 2 3 shows the pin assignments for the SCXI 1121 front connector Chapter 2 Configuration and Installation National Instruments Corporation 2 17 SCXI 1121 User Manual Figure 2 3 SCXI 1121 Front Connector Pin Assignment Pin Number Signal Name Column A B C Signal Name 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 CGND 5 V EGND2 EX1 EGND3 EX3 CH3 EX2 CH2 EGND1 CH1 EGND0 EX0 EX3 CH3 EX2 DTEMP MTEMP CH2 EX1 CH1 EX0 CH0 CH0 SCAL RSVD RSVD Chapter 2 Configuration and Installation SCXI 1121 User Manual 2 18 www natinst com Front Connector Signal Descriptions Pin Signal Name Description A2 CGND Chassis Ground This pin is tied to the SCXI chassis C2 DTEMP Direct Temperature Sensor This pin connects the temperature sensor to the MCH4 when the terminal block is configured for direct temperature connection A4 5 V 5 VDC Source This pin is used to power the temperature sensor on the terminal block 0 2 mA of source not protected C4 MTEMP Multiplexed Temperature Sensor This pin connects the temperature sensor to the output multiplexer A6 SCAL Shunt Calibration This pin is tied to the SCAL b
98. hannel 1 negative input A28 EGND0 Excitation Ground 0 This pin connects to the excitation ground 0 via a 51 k resistor A30 EX0 Positive Excitation Output 0 This pin is connected to the excitation channel 0 positive output C30 EX0 Negative Excitation Output 0 This pin is connected to the excitation channel 0 negative output A32 CH0 Positive Input Channel 0 This pin is connected to the input channel 0 positive input C32 CH0 Negative Input Channel 0 This pin is connected to the input channel 0 negative input Pin Signal Name Description National Instruments Corporation E 1 SCXI 1121 User Manual E SCXI 1121 Cabling This appendix describes how to use and install the hardware accessories for the SCXI 1121 SCXI 1340 cable assembly SCXI 1341 Lab NB Lab PC and Lab PC cable assembly SCXI 1344 Lab LC cable assembly SCXI 1342 PC LPM 16 cable assembly SCXI 1180 feedthrough panel SCXI 1302 50 pin terminal block SCXI 1351 one slot cable extender SCXI 1350 multichassis adapter SCXI 1343 screw terminal adapter SCXI 1340 Cable Assembly The SCXI 1340 cable assembly connects an MIO 16 board to an SCXI 1121 module The SCXI 1340 consists of a 50 conductor ribbon cable that has mounting bracket at one end and a 50 pin female connector at the other end The female connector connects to the I O connector of the MIO 16 board Attached
99. hapter 2 Configuration and Installation SCXI 1121 User Manual 2 26 www natinst com The value of all the nulling resistors on your terminal block is 39 k Notice that these resistors are socketed for easy replacement These sockets best fit a 1 4 W resistor lead size To determine your nulling range use the following formula refer to Figure 2 9 for visual help where Rg is the nominal strain gauge resistance value Rd is either a completion resistor or a second strain gauge nominal resistance Rnull is the nulling resistor value Vexc is the excitation voltage 3 333 or 10 V For example assuming Vexc 3 333 V Rg 120 Rd 120 Rnull 39 k Vnulling 2 56 mV Table 2 11 Nulling Resistors and Corresponding Channel Channel Number Nulling Resistor 0 R3 1 R5 2 R7 3 R9 Vnullingrange Vexc 2 VexcRd Rnull Rg RnullRg Rd Rnull Rg Chapter 2 Configuration and Installation National Instruments Corporation 2 27 SCXI 1121 User Manual Assuming a strain gauge range with a gauge factor of GF 2 and a quarter bridge configuration this range corresponds to 1 498 as given by the strain formula for a quarter bridge strain gauge configuration where Figure 2 9 Nulling Circuit Using the SCXI 1321 with RTDs and Thermistors When using this terminal block w
100. he SCXI 1330 to your module connector and secure it by tightening both mounting screws Figure 2 8 Assembling and Mounting the SCXI 1330 Connector and Shell Assembly Mounting Screw Lock Washers Nut Jack Screws Grounding Screw Mounting Screw Nut Shell Assembly SCXI 1121 Module Shell Assembly Connector Chapter 2 Configuration and Installation SCXI 1121 User Manual 2 24 www natinst com SCXI 1320 SCXI 1328 and SCXI 1321 Terminal Blocks The second type of connector available to connect the transducers to the SCXI 1121 inputs is a terminal block with an onboard temperature sensor and screw terminals for easy connection One terminal block the SCXI 1328 isothermal terminal block has a high accuracy onboard temperature sensor The terminal block kits are listed in the Optional Equipment section in Chapter 1 Introduction The terminal blocks consist of a shielded board with supports for connection to the SCXI 1121 input connector The terminal blocks have 18 screw terminals for easy connection Four pairs of screw terminals are for signal connection to the four inputs of the SCXI 1121 four pairs are for the excitation channels and one pair of screw terminals connects to the chassis ground The following warnings contain important safety information concerning hazardous voltages and terminal blocks Warnings When using the terminal block with high common mode voltages you must insulate your signal wire
101. he first four bytes on the MISO line whenever the module is accessed The bytes will appear least significant byte first Within each byte data is sent out most significant bit first Additional data transfers will result in all zeros being sent on the MISO line The Module ID Register is reinitialized to its original value each time the SCXI 1121 is deselected by the SS signal on the backplane Type Read only Word Size 4 byte Bit Map Byte 0 Byte 1 Byte 2 Byte 3 7 6 5 4 3 2 1 0 0 0 0 0 0 0 1 0 7 6 5 4 3 2 1 0 0 0 0 0 0 0 0 0 7 6 5 4 3 2 1 0 0 0 0 0 0 0 0 0 7 6 5 4 3 2 1 0 0 0 0 0 0 0 0 0 Chapter 4 Register Descriptions National Instruments Corporation 4 3 SCXI 1121 User Manual Configuration Register The Configuration Register contains 16 bits that control the functions of the SCXI 1121 When SS is asserted low and D A indicates data low the register will shift in the data present on the MOSI line bit 15 first and then latch it when the SCXI 1121 is deselected by the SS signal on the backplane The Configuration Register initializes to all zeros when the SCXI chassis is reset or first turned on Type Write only Word Size 16 bit Bit Map Bit Name Description 15 CLKOUTEN Scanclock Output Enable This bit determines whether the SCANCLK signal from the rear signal connector is sent out in inverted form to the TR
102. he module must be able to transfer Analog Bus 0 to the data acquisition board This module must also be able to send a SCANCLK compatible signal on TRIG0 See Chapter 2 Configuration and Installation for more information The module programming steps are as follows 1 Perform any necessary programming to ensure that no modules are driving Analog Bus 0 For an SCXI 1121 clearing AB0EN in the Configuration Register will ensure that its output is not driving AB0 2 Program the module that is connected to the data acquisition board to connect Analog Bus 0 to the data acquisition board but not drive Analog Bus 0 unless it is receiving an active low signal on SCANCON Also program the module to send a SCANCLK compatible signal onto TRIG0 If this module is an SCXI 1121 this programming is accomplished by writing the binary pattern 10ScXXXCC XX001111 to its Configuration Register Note If this module is an SCXI 1121 and is not going to be scanned it is just being used as an interface write a zero to bit 2 SCANCONEN in the Configuration Register The start channel bits become don t care bits 3 Program the other modules to be used in the scan to connect their outputs to Analog Bus 0 but not to drive Analog Bus 0 unless receiving an active low signal on SCANCON Also program the other modules to use TRIG0 as their clock source For SCXI 1121 modules this programming is accomplished by writing the binary pattern 01ScXXXCC XX001111 to th
103. igits Chapter 3 Theory of Operation SCXI 1121 User Manual 3 12 www natinst com You also need a 120 1 4 W precision resistor with tempco less than or equal to 5 ppm or an ammeter with the following specifications Accuracy 0 004 standard 0 016 sufficient Range 0 5 mA Resolution 6 1 2 digits If you use the resistor to calibrate the current excitation you also need an ohmmeter with four wire measurement and the following specifications Accuracy 0 004 standard 0 016 sufficient Range 200 Resolution 5 1 2 digits A multiranging 5 1 2 digit digital multimeter can provide you with most of the necessary functions described previously We will refer to the measuring instrument as a digital multimeter DMM Each channel on the SCXI 1121 has two potentiometers dedicated for calibration For the amplifier channels one potentiometer is used to null the output offset the other is used to null the input offset On the excitation channels one potentiometer is used to adjust the voltage reference while the other is used to adjust the current source Offset Null Adjust Follow these steps to null the offset of the amplifier channels 1 Short the inputs of the DMM together and then connect them to chassis ground 2 Record the measurement indicated by the DMM display This is the DMM inherent offset and should be subtracted from subsequent measurements
104. ion board with each output connected to a different data acquisition board channel See Chapter 2 Configuration and Installation for more information To program the SCXI 1121 for single module parallel scanning write the binary pattern 00ScXXX00 XX000000 to the SCXI 1121 Configuration Register Notice that this can be the RESET state Chapter 5 Programming National Instruments Corporation 5 11 SCXI 1121 User Manual Single Module Multiplexed Scanning Direct To perform simple channel scanning you must cable the SCXI 1121 to a data acquisition board See Chapter 2 Configuration and Installation for more information To program the module for scanned channel measurements write the binary pattern 10ScXXXCC XX001101 to the SCXI 1121 Configuration Register CC represents the starting channel number Single Module Multiplexed Scanning Indirect To indirectly scan a module send the output of the scanned module onto Analog Bus 0 where it will be picked up by another module and transmitted to the data acquisition board Channel Scanning from Other Modules To scan measurements from other modules you must cable the SCXI 1121 to a data acquisition board See Chapter 2 Configuration and Installation for more information The module programming steps are as follows 1 Perform any necessary programming to ensure that no modules are driving Analog Bus 0 For an SCXI 1121 clearing AB0EN in the Configuration Register will en
105. ional Instruments hardware and software product manuals Hardware Reference Database A searchable database containing brief hardware descriptions mechanical drawings and helpful images of jumper settings and connector pinouts Application Notes A library with more than 100 short papers addressing specific topics such as creating and calling DLLs developing your own instrument driver software and porting applications between platforms and operating systems Appendix G Technical Support Resources SCXI 1121 User Manual G 2 www natinst com Software Related Resources Instrument Driver Network A library with hundreds of instrument drivers for control of standalone instruments via GPIB VXI or serial interfaces You also can submit a request for a particular instrument driver if it does not already appear in the library Example Programs Database A database with numerous non shipping example programs for National Instruments programming environments You can use them to complement the example programs that are already included with National Instruments products Software Library A library with updates and patches to application software links to the latest versions of driver software for National Instruments hardware products and utility routines Worldwide Support National Instruments has offices located around the globe Many branch offices maintain a Web site to provide information on loca
106. ister Description Register Description Format The register description chapter discusses each of the SCXI 1121 registers and the Slot 0 registers A detailed bit description of each register is given The individual register description gives the type word size and bit map of the register followed by a description of each bit The register bit map shows a diagram of the register with the MSB shown on the left bit 15 for a 16 bit register bit 7 for an 8 bit register and the LSB shown on the right bit 0 A rectangle is used to represent each bit Each bit is labeled with a name inside its rectangle An asterisk after the bit name indicates that the bit is inverted negative logic The Module ID register has a unique format described in the Module ID Register section In many of the registers several bits are labeled with an X indicating don t care bits When you write to a register you may set or clear these bits without effect SCXI 1121 Registers The SCXI 1121 has two registers The Module ID Register is a four byte read only register that contains the Module ID number of the SCXI 1121 The Configuration Register is a 16 bit write only register that controls the functions and characteristics of the SCXI 1121 Chapter 4 Register Descriptions SCXI 1121 User Manual 4 2 www natinst com Module ID Register The Module ID Register contains the 4 byte module ID code for the SCXI 1121 This code number will be read as t
107. it and is used to control the SCXI 1321 shunt calibration switch CMOS TTL output not protected C6 C8 RSVD Reserved These pins are reserved Do not connect any signal to these pins A8 C10 C16 C22 C28 No Connect Do not connect any signal to these pins A10 EGND3 Excitation Ground 3 This pin connects to the excitation ground 3 via a 51 k resistor A12 EX3 Positive Excitation Output 3 This pin is connected to the excitation channel 3 positive output C12 EX3 Negative Excitation Output 3 This pin is connected to the excitation channel 3 negative output A14 CH3 Positive Input Channel 3 This pin is connected to the input channel 3 positive input C14 CH3 Negative Input Channel 3 This pin is connected to the input channel 3 negative input A16 EGND2 Excitation Ground 2 This pin connects to the excitation ground 2 via a 51 k resistor A18 EX2 Positive Excitation Output 2 This pin is connected to the excitation channel 2 positive output C18 EX2 Negative Excitation Output 2 This pin is connected to the excitation channel 2 negative output Chapter 2 Configuration and Installation National Instruments Corporation 2 19 SCXI 1121 User Manual The signals on the front connector are all analog except pins A6 C6 and C8 which are digital controls These analog signals can be divided into three groups the analog input channels the excitation channels and the temp
108. ith RTDs or thermistor type transducers and with the SCXI 1121 excitation set in the Current mode you must disable the nulling circuit of the channel of interest You can do this in two steps 1 Place the enable disable jumper in position D disable as shown in Table 2 12 2 Remove the nulling resistor from its sockets 4Vr GF 1 2Vr Vr strained voltage static unstrained voltage Vexc Trimmer Potentiometer EX Rd Rg Rnull CH EX SCXI 1321 R R CH Chapter 2 Configuration and Installation SCXI 1121 User Manual 2 28 www natinst com SCXI 1121 Shunt Calibration Shunt calibration circuits are independent from each other but are controlled together In other words when SCAL is set to 1 on the SCXI 1121 all the shunt switches close when SCAL is cleared to 0 all the switches open At startup or reset all switches are open This shunt calibration circuitry configuration places a shunting resistor in parallel with the strain gauge as shown in Figure 2 10 Table 2 12 Jumper Settings of the Nulling Circuits Jumper Position Description W1 Nulling circuit of Channel 0 is enabled factory setting Nulling circuit of Channel 0 is disabled W2 Nulling circuit of Channel 1 is enabled factory setting Nulling circuit of Chann
109. itioning of strain gauges RTDs thermistors thermocouples volt and millivolt sources and 4 to 20 mA sources or 0 to 20 mA process current sources where high common mode voltages exist The SCXI 1121 operates as four isolated input channels and four isolated excitation channels Each channel is isolated and independently configurable via jumpers This manual describes the installation basic programming considerations and theory of operation for the SCXI 1121 Conventions The following conventions appear in this manual lt gt Angle brackets that contain numbers separated by an ellipsis represent a range of values associated with a bit or signal name for example DBIO lt 3 0 gt This icon denotes a note which alerts you to important information This icon denotes a caution which advises you of precautions to take to avoid injury data loss or a system crash This icon denotes a warning which advises you of precautions to take to avoid being electrically shocked bold Bold text denotes items that you must select or click on in the software such as menu items and dialog box options Bold text also denotes parameter names italic Italic text denotes variables emphasis a cross reference or an introduction to a key concept This font also denotes text that is a placeholder for a word or value that you must supply About This Manual SCXI 1121 User Manual xii www natinst com monospace Text in this font denotes
110. itry The following section describes how to program the Slot 0 circuitry for scanning operations For a more detailed description of the Slot 0 scanning circuitry consult the SCXI 1000 1001 User Manual Descriptions of the Slot 0 registers are given in the section Slot 0 Register Descriptions in Chapter 4 Register Descriptions Skip this section if you are doing single module parallel scanning To program the hardscan circuitry perform the following steps 1 Write binary 0000 0000 to the HSCR 2 Write binary 0000 1000 to the HSCR 3 Write the Slot 0 scan list to the FIFO 4 Write binary 0010 1100 to the HSCR 5 Write binary 101S 1100 to the HSCR 6 Write binary 101S 1110 to the HSCR 7 Write binary 101S 1111 to the HSCR To program the hardscan circuitry to use the current scan list perform the following steps 1 Write binary 0000 1000 to the HSCR 2 Write binary 0100 1000 to the HSCR 3 Write binary 0000 1000 to the HSCR 4 Write binary 0010 1100 to the HSCR Chapter 5 Programming SCXI 1121 User Manual 5 14 www natinst com 5 Write binary 101S 1100 to the HSCR 6 Write binary 101S 1110 to the HSCR 7 Write binary 101S 1111 to the HSCR In the preceding steps S 0 if you want the scanning to repeat when the end of the list is reached S 1 if you want the circuitry to shut down after a single scan When you are writing multiple entries to the same register for example
111. l Connector MIO 16 Equivalent 1 2 AOGND AIGND 3 MCH 0 ACH0 4 MCH 0 ACH8 5 MCH 1 ACH1 6 MCH1 ACH9 7 MCH2 ACH2 8 MCH2 ACH10 9 MCH3 ACH3 10 MCH3 ACH11 11 MCH4 ACH4 12 MCH4 ACH12 19 OUTREF AISENSE 24 33 DIG GND DIG GND Appendix E SCXI 1121 Cabling National Instruments Corporation E 3 SCXI 1121 User Manual No other pins are connected on the SCXI 1121 SCXI 1340 Installation Follow these steps to install the SCXI 1340 1 Make sure that the computer and the SCXI chassis are turned off 2 Install the SCXI module in the chassis 3 Plug the mounting bracket connector onto the module rear signal connector see Figure E 1 Make sure the alignment tab on the bracket enters the upper board guide of the chassis 4 Screw the mounting bracket to the threaded strips in the rear of the chassis 5 Connect the loose end of the cable assembly to the MIO 16 board rear signal connector Check the installation After step 1 the order of these steps is not critical however it is easier to locate the correct position for the mounting bracket with a module installed in the chassis If you will attach a cable to the breakout connector installation is easiest if you attach the second cable before installing the SCXI 1340 25 SERDATIN ADIO0 26 SERDATOUT BDIO0 27 DAQD A ADIO1 29 SLOT0SEL ADIO2 36 SCANCLK SCANCLK 37 SERCLK EXT
112. l services You can access these Web sites from www natinst com worldwide If you have trouble connecting to our Web site please contact your local National Instruments office or the source from which you purchased your National Instruments product s to obtain support For telephone support in the United States dial 512 795 8248 For telephone support outside the United States contact your local branch office Australia 03 9879 5166 Austria 0662 45 79 90 0 Belgium 02 757 00 20 Brazil 011 284 5011 Canada Calgary 403 274 9391 Canada Ontario 905 785 0085 Canada Qu bec 514 694 8521 China 0755 3904939 Denmark 45 76 26 00 Finland 09 725 725 11 France 01 48 14 24 24 Germany 089 741 31 30 Greece 30 1 42 96 427 Hong Kong 2645 3186 India 91805275406 Israel 03 6120092 Italy 02 413091 Japan 03 5472 2970 Korea 02 596 7456 Mexico D F 5 280 7625 Mexico Monterrey 8 357 7695 Netherlands 0348 433466 Norway 32 27 73 00 Singapore 2265886 Spain Barcelona 93 582 0251 Spain Madrid 91 640 0085 Sweden 08 587 895 00 Switzerland 056 200 51 51 Taiwan 02 2377 1200 United Kingdom 01635 523545 National Instruments Corporation Glossary 1 SCXI 1121 User Manual Glossary Prefix Meaning Value p pico 10 12 n nano 10 9 micro 10 6 m milli 10 3 k kilo 103 M mega 106 Numbers Symbols degrees ohms strain 5 V signal 5 VDC source signal A A
113. le 2 6 W33 2 6 to 2 7 W38 configuration 2 4 to 2 5 description 2 4 settings table 2 5 W44 configuration 2 3 to 2 4 settings table 2 6 W45 table 2 5 L LabVIEW for Macintosh software 1 3 LabVIEW for Windows software 1 2 LabWindows CVI software 1 2 LOAD bit 4 7 M manual See documentation MCH0 through MCH4 signals table 2 38 B 2 MISO signal description table 3 4 C 3 SCXIbus equivalents for rear signal connector table 3 5 SCXIbus to SCXI 1121 rear signal connector to DAQ board pin equivalences table 2 41 module configuration See configuration Module ID Register description 4 2 overview 3 8 reading from 2 45 to 2 46 timing diagram 2 46 MOSI signal description table 3 4 C 3 SCXIbus equivalents for rear signal connector table 3 5 Index SCXI 1121 User Manual Index 6 www natinst com SCXIbus to SCXI 1121 rear signal connector to DAQ board pin equivalences table 2 41 MTEMP signal table 2 18 D 3 MTS mode terminal blocks 2 31 to 2 32 multiple chassis scanning programming 5 12 to 5 13 theory of operation 3 20 multiplexed output single channel measurements 5 4 to 5 5 multiplexed scanning multiple module description 3 19 programming 5 12 overview 3 17 to 3 18 single module 3 18 to 3 19 direct 3 18 indirect 3 18 to 3 19 programming 5 11 to 5 12 Multiplexed Output mode 3 16 MUXCOUNTER 3 15 to 3 16 N National Instruments Web support G 1 to
114. le extender E 12 SCXI 1180 feedthrough panel E 8 to E 10 description E 8 installation E 9 to E 10 SCXI 1302 50 pin terminal block E 10 to E 11 installation E 11 wiring procedure E 10 to E 11 SCXI 1320 and SCXI 1328 terminal blocks connecting signals 2 24 installation 2 36 insulating signal wires warning 2 24 jumper configuration 2 31 to 2 32 overview 2 24 parts locator diagrams SCXI 1320 2 34 SCXI 1328 2 35 signal connections 2 33 temperature sensor 2 30 to 2 31 SCXI 1321 terminal block features 2 25 installation 2 36 insulating signal wires warning 2 24 jumper configuration 2 30 to 2 31 jumper settings of nulling circuits table 2 28 nulling circuitry 2 25 to 2 27 nulling resistors and corresponding channel table 2 26 overview 2 24 parts locator diagrams 2 36 shunt calibration 2 28 to 2 29 signal connections 2 33 temperature sensor 2 30 to 2 31 trimmer potentiometer and corresponding channel table 2 25 to 2 27 using with RTDs and thermistors 2 27 SCXI 1328 terminal block See SCXI 1320 and SCXI 1328 terminal blocks SCXI 1340 cable assembly description E 1 to E 2 installation E 3 to E 4 SCXI 1121 and MIO 16 pinout equivalences table E 2 to E 3 SCXI 1341 Lab NB Lab PC or Lab PC cable assembly E 4 to E 6 description E 4 to E 6 installation E 6 pin translations table E 5 SCXI 1342 PC LPM 16 cable assembly E 6 to E 8 description E 6 installation E 8 pin translations ta
115. led to that data acquisition board with ribbon cables you are using SCXI 1350 multi chassis adapters leave jumper Chapter 2 Configuration and Installation National Instruments Corporation 2 5 SCXI 1121 User Manual W38 in its factory default position position 1 On all but one of the SCXI 1121s that are cabled to the data acquisition board move jumper W32 to position 3 It does not matter which of the SCXI 1121 modules that are cabled to the data acquisition board has jumper W32 set to position 1 If you have different types of modules cabled to the data acquisition board those different modules will have jumpers similar to W38 and W32 of the SCXI 1121 Set those jumpers on the different modules using the same method described here for the SCXI 1121 On Revision A and B SCXI 1121s jumper W32 is not used You set jumper W38 as explained in the cases above except in the case of a multiple chassis ribbon cable system In a multichassis ribbon cable system with Revision A and B SCXI 1121s cabled to the data acquisition board you can access the MISO line in only one chassis Pick one of the chassis and set jumper W38 to position 1 on the SCXI 1121 in that chassis that is cabled to the data acquisition board On the SCXI 1121s that are in the other chassis and cabled to the data acquisition board set jumper W38 to position 3 Notice that you will only be able to access digital information from the chassis that has the SCXI 1121 with jump
116. llation for more detailed information on timing Detailed signal specifications are also included in Chapter 2 Pin Signal Name Description 1 2 AOGND Analog Output Ground These pins are connected to the analog reference when jumper W33 is in position AB R0 3 12 MCH0 through MCH4 Analog Output Channels 0 through 4 Connects to the data acquisition board differential analog input channels 19 OUTREF Output Reference This pin serves as the reference node for the analog channels output in the Pseudodifferential Reference mode It should be connected to the analog input sense of the NRSE data acquisition board 24 33 DIG GND Digital Ground These pins supply the reference for data acquisition board digital signals and are tied to the module digital ground 25 SERDATIN Serial Data In This signal taps into the SCXIbus MOSI line to provide serial input data to a module or Slot 0 26 SERDATOUT Serial Data Out This signal taps into the SCXIbus MISO line to accept serial output data from a module 27 DAQD A Data Acquisition Board Data Address Line This signal taps into the SCXIbus D A line to indicate to the module whether the incoming serial stream is data or address information 29 SLOT0SEL Slot 0 Select This signal taps into the SCXIbus INTR line to indicate whether the information on MOSI is being sent to a module or Slot 0 36 SCANCLK Scan Clock This indicates to the SCXI 1121 that a sample
117. m Cables 1 5 Unpacking 1 6 Chapter 2 Configuration and Installation Module Configuration 2 1 Digital Signal Connections 2 3 Jumper W44 2 3 Jumper W38 2 4 Jumper W32 2 4 Using Jumpers W32 and W38 2 4 Analog Configuration 2 6 Grounding Shielding and Reference Mode Selection 2 6 Input Channel Jumpers 2 8 Excitation Jumpers 2 9 Hardware Installation 2 14 Signal Connections
118. marks or trade names of their respective companies WARNING REGARDING USE OF NATIONAL INSTRUMENTS PRODUCTS 1 NATIONAL INSTRUMENTS PRODUCTS ARE NOT DESIGNED WITH COMPONENTS AND TESTING FOR A LEVEL OF RELIABILITY SUITABLE FOR USE IN OR IN CONNECTION WITH SURGICAL IMPLANTS OR AS CRITICAL COMPONENTS IN ANY LIFE SUPPORT SYSTEMS WHOSE FAILURE TO PERFORM CAN REASONABLY BE EXPECTED TO CAUSE SIGNIFICANT INJURY TO A HUMAN 2 IN ANY APPLICATION INCLUDING THE ABOVE RELIABILITY OF OPERATION OF THE SOFTWARE PRODUCTS CAN BE IMPAIRED BY ADVERSE FACTORS INCLUDING BUT NOT LIMITED TO FLUCTUATIONS IN ELECTRICAL POWER SUPPLY COMPUTER HARDWARE MALFUNCTIONS COMPUTER OPERATING SYSTEM SOFTWARE FITNESS FITNESS OF COMPILERS AND DEVELOPMENT SOFTWARE USED TO DEVELOP AN APPLICATION INSTALLATION ERRORS SOFTWARE AND HARDWARE COMPATIBILITY PROBLEMS MALFUNCTIONS OR FAILURES OF ELECTRONIC MONITORING OR CONTROL DEVICES TRANSIENT FAILURES OF ELECTRONIC SYSTEMS HARDWARE AND OR SOFTWARE UNANTICIPATED USES OR MISUSES OR ERRORS ON THE PART OF THE USER OR APPLICATIONS DESIGNER ADVERSE FACTORS SUCH AS THESE ARE HEREAFTER COLLECTIVELY TERMED SYSTEM FAILURES ANY APPLICATION WHERE A SYSTEM FAILURE WOULD CREATE A RISK OF HARM TO PROPERTY OR PERSONS INCLUDING THE RISK OF BODILY INJURY AND DEATH SHOULD NOT BE RELIANT SOLELY UPON ONE FORM OF ELECTRONIC SYSTEM DUE TO THE RISK OF SYSTEM FAILURE TO AVOID DAMAGE INJURY OR DEATH THE USER OR APPLICATION DESIGNER MUST TAKE REASON
119. mation Single Module Multiplexed Scanning Single Module Multiplexed Scanning Direct This is the simplest multiplexed scanning mode Directly cable the SCXI 1121 to the data acquisition board as shown in Figure 3 8 The module sends SCANCLK onto TRIG0 and Slot 0 sends SCANCON back to the module SCANCON will be low at all times during the scan except during changes from one Slot 0 scan list entry to the next when SCANCON pulses high to make the MUXCOUNTER reload its starting channel Notice that although you are using only a single module you can put many entries with different counts in the Slot 0 FIFO so that some channels are read more often than others You cannot change the start channel in the module Configuration Register during a scan Figure 3 8 Single Module Multiplexed Scanning Direct Single Module Multiplexed Scanning Indirect In this mode the SCXI 1121 is not directly cabled to the data acquisition board Instead you connect another module to the data acquisition board and the analog output of the SCXI 1121 is sent over Analog Bus 0 through the intermediate module and then to the data acquisition board The SCXI 1121 receives its MUXCOUNTER clock from TRIG0 which is sent by the intermediate module as illustrated in Figure 3 9 Slot 0 operation is the same for direct connection scanning Cable Assembly Data Acquisition Board Analog Input Timing Output TRIG0 SCANCON X SCANCLK MCH0 SLOT 0
120. minal adapter 776574 43 SCXI 1344 Lab LC cable assembly 776574 44 SCXI 1346 shielded multichassis cable adapter 776574 46 SCXI 1347 SCXI shielded cable assembly with 1 m cable 776574 471 with 2 m cable 776574 472 with 5 m cable 776574 475 with 10 m cable 776574 470 SCXI 1349 SCXI shielded cable assembly with 1 m cable 776574 491 with 2 m cable 776574 492 with 5 m cable 776574 495 with 10 m cable 776574 490 SCXI 1350 multichassis adapter 776575 50 SCXI process current resistor kit 776582 01 Standard ribbon cable 0 5 m 180524 05 1 0 m 180524 10 Chapter 1 Introduction National Instruments Corporation 1 5 SCXI 1121 User Manual Refer to the Signal Connections section in Chapter 2 Configuration and Installation and to Appendix E SCXI 1121 Cabling for additional information on cabling connectors and adapters Custom Cables The SCXI 1121 rear signal connector is a 50 pin male ribbon cable header The manufacturer part number used by National Instruments for this header is as follows AMP Inc part number 1 103310 0 The mating connector for the SCXI 1121 rear signal connector is a 50 position polarized ribbon socket connector with strain relief National Instruments uses a polarized or keyed connector to prevent inadvertent upside down connection to the SCXI 1121 Recommended manufacturer part numbers for this mating connector are as follows Electronic Products Di
121. mming the data acquisition boards involves writes to their registers See your data acquisition board user manual for more information The programming instructions list the sequence of steps to take The instructions are language independent that is they instruct you to write a value to a given register without presenting the actual code Notation For the bit patterns to be written the following symbols are used 0 Binary zero 1 Binary one X Don t care either zero or one may be written C One of two bits used to specify the channel to be loaded into the MUXCOUNTER This value will either be the channel to be read for single reads or a starting channel for scanned measurements The 16 bit patterns are presented MSB first left to right Chapter 5 Programming SCXI 1121 User Manual 5 2 www natinst com Register Writes This section describes how to write to the Configuration Register HSCR and FIFO Register including the procedure for writing to the Slot Select Register to select the appropriate slot For timing specifics refer to the Timing Requirements and Communication Protocol section in Chapter 2 Configuration and Installation The rear signal connector pin equivalences to the different National Instruments data acquisition boards are given in Table 5 1 See also Appendix E SCXI 1121 Cabling The Configuration Register the FIFO Register and the HSCR are write only registers The different bits in these register
122. n addition lowpass filtering is available at the inputs You can jumper select one of two bandwidths 10 kHz or 4 Hz The amplifier gain is divided into two stages a first stage providing gains of 1 10 50 and 100 and a second stage providing gains of 1 2 5 10 and 20 Also the module has an internal completion network that can be used with half bridge or quarter bridge networks Each channel is configurable to a different bandwidth gain or completion network operation Use the following formula to determine the overall gain of a given amplifier input channel where Gtotal is the overall gain and G1st and G2nd are the first and second stage gains It is important to note that the choice of gain in each stage will affect the amplifier bandwidth To determine the bandwidth of a given gain stage use the following formula where BW is a given amplifier stage bandwidth GBWP is the gain bandwidth product typically 800 kHz and G is the gain at this stage This BW might be of concern at high first stage gains such as 50 and 100 In this case the first stage amplifier has a BW equal to 16 kHz and 8 kHz respectively Because of this decrease in the amplifier bandwidth the channel overall bandwidth decreases but noise immunity improves If this bandwidth limitation is unacceptable you should spread the gains over both stages thus increasing the BW of each amplifier stage In most cases this will introduce a negligible effect on the channel
123. ng on the state of RTEMP If FOUTEN is cleared to zero the MCH0 pins will be driven through a buffer by the selected channel output or the MTEMP line If FOUTEN is set to one the MCH0 pins will not be driven by the selected channel output or MTEMP unless SCANCON is active low and the SCANCONEN bit is cleared If the selected channel output or MTEMP is driving the output buffer it will drive Analog Bus 0 if AB0EN is set If nothing is driving the output buffer the SCXI 1121 output will saturate Slot 0 Register Descriptions Slot 0 has three registers The Slot Select Register is a 16 bit write only register that determines with which slot the data acquisition board will speak when SLOT0SEL is released high In the case of the SCXI 1001 chassis the Slot Select Register also determines in which chassis the desired slot is The FIFO Register is a 16 bit write only register used for storing the Slot 0 scan list that determines the chassis scan sequence The Hardscan Control Register HSCR is an 8 bit write only register used for setting up the timing circuitry in Slot 0 The Slot Select Register is written to by using the SLOT0SEL line The HSCR and the FIFO Register are written to as if they were registers located on modules in Slots 13 and 14 It is recommended that you maintain software copies of the Slot Select Register HSCRs and all the Slot 0 scan lists that correspond to the writes to FIFO Registers If you are using multi
124. nt Typical resistor values range from 100 k to 1 M This solution although necessary in this case lowers the input impedance of the input channel amplifier and introduces an additional offset voltage proportional to the input bias current and to the resistor value used The typical input bias current of the amplifier consists of 80 pA and a negligible offset drift current When a 100 k resistor is used this will result into 8 V of offset which is insignificant in most applications However if larger resistors are used significant input offset may result To determine the maximum offset introduced by the biasing resistor use the following equation The input signal range of an SCXI 1121 input channel is 5 V Gtotal referenced to its negative input where Gtotal is equal to the product of the first stage and second stage gains In addition the input channels are overvoltage protected to 250 Vrms with power on or off at a maximum of 4 5 mArms sink or source Vs Vout Rbias Module Vs Vout Rbias Vcm High CMV Module Vofsbias Ibias Rbias Chapter 2 Configuration and Installation SCXI 1121 User Manual 2 22 www natinst com Warning Exceeding the input signal range and the common mode input range results in distorted signals Exceeding the maximum input voltage rating 250 Vrms between positive and negative terminals and between any terminal and
125. nual Remember to account for the gains of both the SCXI 1121 and the data acquisition board when calculating the actual voltage present at the input of the SCXI 1121 To measure one of the four differential input channels to the SCXI 1121 or the DTEMP line if the module has been configured appropriately perform the following steps 1 Write the binary pattern 000XXX00 XX000000 to the SCXI 1121 Configuration Register Notice that this can be the RESET state 2 Measure the voltage with the data acquisition board Multiplexed Output In order to perform a direct multiplexed output measurement you must cable the SCXI 1121 rear signal connector to a data acquisition board See Chapter 2 Configuration and Installation for more information For information on how to make the voltage measurement with your data acquisition board consult your data acquisition board user manual Remember to account for the gains of both the SCXI 1121 and the data acquisition board when calculating the actual voltage present at the input of the SCXI 1121 Chapter 5 Programming National Instruments Corporation 5 5 SCXI 1121 User Manual To measure one of the four differential input channels to the SCXI 1121 perform the following steps 1 Write the binary pattern 000XXXCC XX000000 to the SCXI 1121 Configuration Register 2 Measure the voltage with the data acquisition board To shunt calibrate one of the four differential input channels pe
126. nued Rear Signal Connector Pin SCXI 1121 Use Connection Type Appendix E SCXI 1121 Cabling SCXI 1121 User Manual E 16 www natinst com 39 No Connect Solder pad 40 No Connect Solder pad 41 No Connect Solder pad 42 No Connect Solder pad 43 RSVD Solder pad 44 No Connect Solder pad 45 No Connect Solder pad 46 No Connect Solder pad 47 No Connect Solder pad 48 No Connect Solder pad 49 No Connect Solder pad 50 No Connect Solder pad Table E 4 SCXI 1343 Pin Connections Continued Rear Signal Connector Pin SCXI 1121 Use Connection Type National Instruments Corporation F 1 SCXI 1121 User Manual F Revision A and B Photo and Parts Locator Diagrams This appendix contains a photograph of the Revision A and B SCXI 1121 signal conditioning module and the general and detailed parts locator diagrams Figure F 1 shows the SCXI 1121 module Figures F 2 and F 3 show the general and detailed parts locator diagrams of the Revision A and B SCXI 1121 Figure F 1 Revision A and B SCXI 1121 Signal Conditioning Module Appendix F Revision A and B Photo and Parts Locator Diagrams SCXI 1121 User Manual F 2 www natinst com Figure F 2 Revision A and B SCXI 1121 General Parts Locator Diagram Appendix F Revision A and B Photo and Parts Locator Diagrams National Instruments Corporation F 3 SCXI 1121 User Manual Figure F 3 Revision A and B SCXI 1121 Detailed Parts Locator
127. o 3 16 calibration 3 11 to 3 14 excitation output channels 3 11 analog configuration 2 6 to 2 13 excitation jumpers 2 9 to 2 13 current and voltage jumpers 2 9 to 2 10 excitation level 2 10 to 2 11 internal half bridge completion 2 12 to 2 13 grounding shielding and reference mode selection 2 6 to 2 7 input channel jumpers 2 8 to 2 13 excitation jumpers 2 9 to 2 13 filter jumpers 2 9 gain jumpers 2 8 jumper W33 2 6 to 2 7 analog input channels block diagram 3 9 signal connections 2 20 to 2 22 AC coupled with high common mode voltage figure 2 21 exceeding input range and common mode input range warning 2 22 floating referenced to chassis ground figure 2 20 floating AC coupled figure 2 21 ground referenced with high common mode voltage figure 2 20 theory of operation 3 8 to 3 11 analog input specifications A 1 to A 2 analog output circuitry 3 15 to 3 16 analog output signal connections 2 39 AOGND signal table 2 38 B 2 B bits AB0EN 4 4 CHAN lt 1 0 gt 4 4 CHS lt 4 0 gt 4 6 CLKEN 4 8 CLKOUTEN 4 3 CLKSELECT 4 3 CNT lt 6 0 gt 4 9 FOUTEN 4 5 FRT 4 7 HSRS 4 7 LOAD 4 7 ONCE 4 7 RD 4 7 RTEMP 4 4 SCAL 4 3 SCANCLKEN 4 4 SCANCONEN 4 4 4 8 SL lt 3 0 gt 4 6 Index SCXI 1121 User Manual Index 2 www natinst com C cable assemblies See SCXI 1121 cabling cables custom 1 5 calibration 3 11 to 3 14 equipment requirements 3 11 to 3 12 excitation
128. o leave jumper W33 in its factory setting or in position AB R1 to avoid ground loops With data acquisition boards that are configured for referenced single ended RSE measurements W33 should be in position AB R0 to connect the SCXI 1121 ground to the data acquisition analog ground Pin 19 is the OUTREF pin this pin is connected internally to the analog reference when jumper W33 is in position AB R2 Pins 3 through 12 are the analog output channels of the SCXI 1121 Pins 3 and 4 or MCH0 are a multiplexed output of all four input channels and the temperature sensor output Pins 5 through 10 or MCH1 through MCH3 are a parallel connection of input channels 1 through 3 to the rear signal connector Pins 11 and 12 or MCH4 are a direct connection of the temperature sensor Notice that the temperature sensor is located on the terminal block For further details on configuring the temperature sensor output refer to the SCXI 1320 SCXI 1328 and SCXI 1321 Terminal Blocks section earlier in this chapter Warning The SCXI 1121 analog outputs are not overvoltage protected Applying external voltages to these outputs can damage the SCXI 1121 National Instruments is not liable for any damages resulting from such signal connections Note The SCXI 1121 analog outputs are short circuit protected Chapter 2 Configuration and Installation SCXI 1121 User Manual 2 40 www natinst com Digital I O Signal Connections Pins 24 through 27 29 33 36 3
129. ocks the serial data on the MOSI and MISO lines Open collector I O C23 MOSI Master Out Slave In Transmits data from the SCXIbus to the module Open collector I O Appendix C SCXIbus Connector SCXI 1121 User Manual C 4 www natinst com Further information is given in Chapter 3 Theory of Operation A24 TRIG0 TRIG0 General purpose trigger line used by the SCXI 1121 to send SCANCLK to other modules or receive SCANCLK from other modules Open collector I O B24 SS Slot Select When low enables module communications over the SCXIbus Totem pole Input C24 SCANCON Scanning Control Combination output enable and reload signal for scanning operations Totem pole Input All other pins are not connected Pin Signal Name Description National Instruments Corporation D 1 SCXI 1121 User Manual D SCXI 1121 Front Connector This appendix describes the pinout and signal names for the SCXI 1121 front connector including a description of each connection Appendix D SCXI 1121 Front Connector SCXI 1121 User Manual D 2 www natinst com Figure D 1 shows the pin assignments for the SCXI 1121 front connector Figure D 1 SCXI 1121 Front Connector Pin Assignment Pin Number Signal Name Column A B C Signal Name 32 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 CGND
130. ode Leave jumper W1 in position A on the SCXI 1342 The SCXI 1121 does not use jumper W1 Table E 3 lists the SCXI 1342 pin translations Appendix E SCXI 1121 Cabling National Instruments Corporation E 7 SCXI 1121 User Manual Table E 3 SCXI 1342 Pin Translations PC LPM 16 Pin PC LPM 16 Signal Rear Signal Connector Pin SCXI 1121 Use 1 2 AIGND 1 2 AOGND 3 ACH0 3 MCH0 4 ACH8 4 MCH0 5 ACH1 5 MCH1 6 ACH9 6 MCH1 7 ACH2 7 MCH2 8 ACH10 8 MCH2 9 ACH3 9 MCH3 10 ACH11 10 MCH3 11 ACH4 11 MCH4 12 ACH12 12 MCH4 13 ACH5 13 No Connect 14 ACH13 14 No Connect 15 ACH6 15 No Connect 16 ACH14 16 No Connect 17 ACH7 17 No Connect 18 ACH15 18 No Connect 19 50 DGND 24 33 DIG GND 28 DIN6 26 SERDATOUT 29 DIN7 28 No Connect 34 DOUT4 25 SERDATIN 35 DOUT5 27 DAQD A 36 DOUT6 29 SLOT0SEL 37 DOUT7 37 SERCLK 46 OUT2 46 No Connect 49 5 V 34 35 No Connect Appendix E SCXI 1121 Cabling SCXI 1121 User Manual E 8 www natinst com All other pins of the PC LPM 16 pinout are not sent to the SCXI 1121 rear signal connector SCXI 1342 Installation Follow these steps to install the SCXI 1342 1 Make sure that the computer and the SCXI chassis are turned off 2 Install the SCXI module to which the SCXI 1342 will connect 3 Connect one end of the ribbon cable to the adapter board rear conn
131. om Input Channel Jumpers Gain Jumpers Each input channel has two gain stages The first gain stage provides gains of 1 10 50 and 100 and the second stage provides gains of 1 2 5 10 and 20 Tables 2 3 and 2 4 show how to set up the gain for each channel The board is shipped to you with the first stage gain set to 100 position A and a second stage gain set to 10 position D To change the gain of your module move the appropriate jumper on your module to the position indicated in Table 2 4 Refer to Figure 2 2 for the jumper locations on your module To determine the overall gain of a given channel use the following formula Overall gain First stage gain second stage gain Table 2 3 Gain Jumper Allocation Input Channel Number First Gain Jumper Second Gain Jumper 0 W3 W4 1 W19 W20 2 W29 W30 3 W41 W42 Table 2 4 Gain Jumper Positions Gain Setting Jumper Position First stage 1 10 50 100 D C B A factory setting Second stage 1 2 5 10 20 A B C D factory setting E Chapter 2 Configuration and Installation National Instruments Corporation 2 9 SCXI 1121 User Manual Filter Jumpers Two stage filtering is also available on your SCXI 1121 module The first stage is located in the isolated section of the input channel whereas the second stage is located in the nonisolated section of the input channel This permits a higher signal to noise ratio by eliminatin
132. on You can multiplex several SCXI 1121s into a single channel thus greatly increasing the number of analog input signals that can be digitized The addition of a shielded terminal block provides screw terminals for easy signal attachment to the SCXI 1121 In addition a temperature sensor for cold junction compensation of thermocouples is included on the terminal block This cold junction reference CJR is either multiplexed along with the four input channels or connected by jumpers to a different channel of the data acquisition board With the SCXI 1121 the SCXI chassis can serve as a fast scanning signal conditioner for laboratory testing production testing and industrial process monitoring Chapter 1 Introduction SCXI 1121 User Manual 1 2 www natinst com What Your Kit Should Contain The contents of the SCXI 1121 kit part number 776572 21 are listed as follows If your kit is missing any of the components contact National Instruments Optional Software This manual contains complete instructions for directly programming the SCXI 1121 You can order separate software packages for controlling the SCXI 1121 from National Instruments When you combine the PC AT and MC data acquisition boards with the SCXI 1121 you can use LabVIEW for Windows or LabWindows for DOS LabVIEW and LabWindows are innovative program development software packages for data acquisition and control applications LabVIEW uses graphical programming
133. onverts the data acquisition board signals to open collector signals on the backplane of the SCXI chassis In order for the data acquisition board to talk to a slot the board must first assert the SS for that slot This is done by asserting INTR low writing a 16 bit number over MOSI corresponding to the desired slot and chassis if an SCXI 1001 A24 TRIG0 TRIG0 General purpose trigger line used by the SCXI 1121 to send SCANCLK to other modules or receive SCANCLK from other modules Open collector I O B24 SS Slot Select When low enables module communications over the SCXIbus Totem pole Input C24 SCANCON Scanning Control Combination output enable and reload signal for scanning operations Totem pole Input All other pins are not connected Table 3 1 SCXIbus Equivalents for the Rear Signal Connector Rear Signal Connector Signal SCXIbus Equivalent SERDATIN MOSI DAQD A D A SLOT0SEL INTR Jumper W44 must be set to position 1 SERCLK SPICLK SERDATOUT MISO Jumper W38 must be set to position 1 Pin Signal Name Description Chapter 3 Theory of Operation SCXI 1121 User Manual 3 6 www natinst com chassis is being used and then releasing INTR high At this point SS of the desired slot is asserted low and the data acquisition board can communicate with the module in that slot according to the SPI protocol Digital Interface Figure 3 3 shows a diagram of the SCXI 1121 and SCXIbus digital
134. ple chassis it is important to understand the architectural differences of the Slot Select Register as compared to the HSCR and the FIFO Register Although each chassis has its own physical Slot Select Register all are written to at the same time The jumper settings in Slot 0 of a chassis determine with which chassis number Slot 0 is identified From the software perspective only one Slot Select Register exists in a system composed of multiple chassis The HSCR and FIFO Register on the other hand are unique to each chassis and you must program them separately Chapter 4 Register Descriptions SCXI 1121 User Manual 4 6 www natinst com Slot Select Register The Slot Select Register contains 16 bits that determine which module in which chassis will be enabled for communication when the SLOT0SEL line is set to one An SCXI 1000 chassis will select the appropriate module in its chassis regardless of the chassis number written The Slot Select Register will shift in the data present on the MOSI line bit 16 first when SLOT0SEL is cleared to zero Type Write only Word Size 16 bit Bit Map Bit Name Description 15 9 X Don t care bits 8 4 CHS lt 4 0 gt Chassis Bit 4 through 0 These bits determine which chassis is selected On the SCXI 1000 chassis these bits are don t cares 3 0 SL lt 3 0 gt Slot Bit 3 through 0 These bits determine which slot in the selected chassis is selected 15 14 13 12 11
135. programming the Slot 0 hardscan circuitry See Chapter 5 Programming for information on programming the Slot 0 hardscan circuitry The following sections detail the procedure for selecting a slot in a particular chassis Figure 2 16 illustrates the timing of this procedure with the example case of selecting Slot 11 in Chassis 9 Notice that the factory default chassis address for the SCXI 1000 is address 0 For information on changing the address of your chassis consult the SCXI 1000 1001 User Manual An SCXI 1000 chassis will respond to any chassis number Tlow Thigh SCANCLK Tlow Time low before rising edge 400 nsec minimum Thigh Time high before falling edge 250 nsec minimum Chapter 2 Configuration and Installation National Instruments Corporation 2 43 SCXI 1121 User Manual Figure 2 16 Slot Select Timing Diagram To write the 16 bit slot select number to Slot 0 follow these steps 1 Initial conditions SERDATIN don t care DAQD A don t care SLOT0SEL 1 SERCLK 1 2 Clear SLOT0SEL to 0 This will deassert all SS lines to all modules in all chassis 3 For each bit starting with the most significant bit perform the following action a SERDATIN bit to be sent These bits are the data that is being written to the Slot Select Register b SERCLK 0 c SERCLK 1 This rising edge clocks the data 4 Set SLOT0SEL to 1 This will assert the SS line of the module whose slot
136. provides all channels to the data acquisition board at all times You can implement single module parallel scanning with any data acquisition board that is appropriately cabled to the SCXI 1121 Figure 3 7 Single Module Parallel Scanning Multiplexed Scanning Only the MIO 16 data acquisition boards support multiplexed scanning on the SCXI 1121 During multiplexed scanning a module sends the SCANCLK signal to Slot 0 over the TRIG0 backplane line and Slot 0 sends unique SCANCON signals to each module Each module uses its signal to reload MUXCOUNTER and to determine when the SCXI 1121 output is enabled Slot 0 contains a module list first in first out FIFO memory chip similar to the Channel Gain FIFO on an MIO 16 board except that instead of having a channel number and gain setting for each entry the Slot 0 FIFO contains a slot number and a sample count for each Four Isolated Floating Single Ended Inputs CH0 CH1 CH2 CH3 MCH0 MCH1 MCH2 MCH3 Analog Input 0 Analog Input 1 Analog Input 2 Analog Input 3 Data Acquisition Board SCXI 1121 Cable Assembly Chapter 3 Theory of Operation SCXI 1121 User Manual 3 18 www natinst com entry The list in Slot 0 will determine which module is being accessed and for how many samples It is important that you make sure that the lists on the data acquisition board and Slot 0 are compatible so that the samples are acquired as intended See your SCXI chassis manual for more infor
137. quarter bridge setup you must use an extra resistor to complete the bridge Place this resistor on the terminal block between the positive input channel and the negative excitation output Table 2 9 Completion Network Jumpers Channel Jumpers Enable Completion Disable Network Factory Setting 0 W1 and W2 1 W17 and W18 A B W2 W1 1 2 3 A B W2 W1 1 2 3 A B W18 W17 1 2 3 A B W18 W17 1 2 3 Chapter 2 Configuration and Installation National Instruments Corporation 2 13 SCXI 1121 User Manual 2 W27 and W28 3 W39 and W40 Table 2 9 Completion Network Jumpers Continued Channel Jumpers Enable Completion Disable Network Factory Setting A B W28 W27 1 2 3 A B W28 W27 1 2 3 A B W40 W39 1 2 3 A B W40 W39 1 2 3 Chapter 2 Configuration and Installation SCXI 1121 User Manual 2 14 www natinst com Hardware Installation You can install the SCXI 1121 in any available SCXI chassis After you have made any necessary changes and have verified and re
138. r 3 Program the other module to drive Analog Bus 0 with the signal to be measured 4 Measure the voltage with the data acquisition board Chapter 5 Programming SCXI 1121 User Manual 5 6 www natinst com Measurements from the SCXI 1121 via Another Module To perform measurements via another module you must cable the other module rear signal connector to a data acquisition board The other module must also be able to transfer Analog Bus 0 to the data acquisition board See Chapter 2 Configuration and Installation for more information To measure one of the four differential input channels to the SCXI 1121 perform the following steps 1 Perform any necessary programming to ensure that no modules are driving Analog Bus 0 For an SCXI 1121 clearing AB0EN in the Configuration Register will ensure that its output is not driving AB0 2 Program the other module not to drive Analog Bus 0 but to send Analog Bus 0 to the data acquisition board 3 Write the binary pattern 000XXXCC XX000010 to the SCXI 1121 Configuration Register 4 Measure the voltage with the data acquisition board To perform a shunt calibration on one of the four differential input channels of the SCXI 1121 perform the following steps 1 Perform any necessary programming to ensure that no modules are driving Analog Bus 0 For an SCXI 1121 clearing AB0EN in the Configuration Register will ensure that its output is not driving AB0 2 Program
139. ration and Installation SCXI 1121 User Manual 2 36 www natinst com Figure 2 13 SCXI 1321 Parts Locator Diagram Terminal Block Installation To connect the terminal block to the SCXI 1121 front connector perform the following steps 1 Connect the SCXI 1121 front connector to its mating connector on the terminal block 2 Make sure that the SCXI 1121 top and bottom thumbscrews do not obstruct the rear panel of the terminal block 3 Tighten the top and bottom screws on the back of the terminal block to hold it securely in place Chapter 2 Configuration and Installation National Instruments Corporation 2 37 SCXI 1121 User Manual Rear Signal Connector Note If you are using the SCXI 1121 with a National Instruments data acquisition board and cable assembly you do not need to read the remainder of this chapter If you are using the SCXI 1180 feedthrough panel the SCXI 1343 rear screw terminal adapter or the SCXI 1351 one slot cable extender with the SCXI 1121 you should read this section Figure 2 14 shows the pin assignments for the SCXI 1121 rear signal connector Figure 2 14 SCXI 1121 Rear Signal Connector Pin Assignment RSVD SERCLK DIG GND SLOT0SEL DAQD A SERDATIN OUTREF MCH4 MCH3 MCH2 MCH1 MCH0 AOGND SCANCLK SERDATOUT DIG GND MCH4 MCH3 MCH2 MCH1 MCH0 AOGND 49 50 47 48 45 46 43 44 41 42 39 40 37 38 35 36 33 34 31 32 29
140. rform the following steps 1 Write the binary pattern 001XXXCC XX00000 to the SCXI 1121 Configuration Register Insert a delay of at least 1 sec if you have set the 4 Hz filter or at least 1 msec if you have set the 10 kHz filter This delay permits the SCXI 1121 amplifier to settle 2 Measure the voltage with the data acquisition board To measure the voltage on the MTEMP line perform the following steps 1 Write the binary pattern 000XXXXX XX100000 to the SCXI 1121 Configuration Register 2 Measure the voltage with the data acquisition board Indirect Measurements Indirect measurements involve one module sending a signal to Analog Bus 0 where it is picked up by another module and transmitted to the data acquisition board Measurements from Other Modules To perform measurements from other modules you must cable the SCXI 1121 rear signal connector to a data acquisition board See Chapter 2 Configuration and Installation for more information To make a measurement from another module perform the following steps 1 Perform any necessary programming to ensure that no modules are driving Analog Bus 0 For an SCXI 1121 clearing AB0EN in the Configuration Register will ensure that its output is not driving AB0 2 Write the binary pattern 000XXXXX XX100011 to the SCXI 1121 Configuration Register This step disables the SCXI 1121 from driving Analog Bus 0 and allows Analog Bus 0 to drive MCH0 through the output buffe
141. rough software or hardware and service the data acquisition The MIO and Lab PC boards can do all types of scanning Lab NB Lab PC Lab PC Lab LC and PC LPM 16 boards support only single module parallel scanning and do not support any of the multiplexed scanning modes Notice that single module parallel scanning is typically done without any module or Slot 0 programming only programming the data acquisition board is necessary 1 Data Acquisition Board Setup Programming The programming steps for your data acquisition board are given in your data acquisition board user manual You should follow the instructions in the following sections AT MIO 16 User Manual Multiple A D Conversions with Continuous Channel Scanning Round Robin Multiple A D Conversions with Interval Channel Scanning Pseudosimultaneous AT MIO 16D User Manual Multiple A D Conversions with Continuous Channel Scanning Round Robin Multiple A D Conversions with Interval Channel Scanning Pseudosimultaneous AT MIO 16F 5 User Manual Posttrigger Data Acquisition with Continuous Channel Scanning Posttrigger Data Acquisition with Interval Channel Scanning Chapter 5 Programming SCXI 1121 User Manual 5 8 www natinst com AT MIO 16X User Manual Continuous Channel Scanning Data Acquisition Interval Channel Scanning Data Acquisition AT MIO 64F 5 User Manual Continuous Chann
142. s appropriately National Instruments is not liable for any damages or injuries resulting from inadequate signal wire insulation If high voltages 42 Vrms are present you must connect the safety earth ground to the strain relief tab This complies with UL 1244 and protects against electric shock when the terminal block is not connected to the chassis To connect the safety earth ground to the strain relief tab run an earth ground wire in the cable from the signal source to the terminal block National Instruments is not liable for any damages or injuries resulting from inadequate safety earth ground connections SCXI 1320 and SCXI 1328 Terminal Blocks When connecting your signals to the SCXI 1320 terminal block for use with the SCXI 1121 follow the labeling on the SCXI 1320 indicated under the module type column for the SCXI 1121 as indicated in Figure 2 11 When connecting your signals to the SCXI 1328 high accuracy isothermal terminal block for use with the SCXI 1121 follow the labeling on the SCXI 1328 indicated along the module type row for the SCXI 1121 as indicated in Figure 2 12 Chapter 2 Configuration and Installation National Instruments Corporation 2 25 SCXI 1121 User Manual SCXI 1321 Offset Null and Shunt Calibration Terminal Block The SCXI 1321 terminal block operates only with Revision C and later SCXI 1121 modules In addition to the 18 screw terminals the SCXI 1321 has circuitry for offset null adjust of
143. s often control independent pieces of circuitry There are times when you may want to set or clear a specific bit or bits without affecting the remaining bits However a write to one of these registers will affect all bits simultaneously You cannot read the registers to determine which bits have been set or cleared in the past therefore you should maintain a software copy of these registers You can then read the software copy to determine the status of the register To change the state of a single bit without disturbing the remaining bits set or clear the bit in the software copy and write the software copy to the register Register Selection and Write Procedure 1 Select the slot of the module to be written to or Slot 13 or 14 Initial conditions SERDATIN X DAQD A X SLOT0SEL 1 SERCLK 1 2 Clear SLOT0SEL to 0 This will deassert all SS lines to all modules in all chassis Table 5 1 SCXI 1121 Rear Signal Connector Pin Equivalences SCXIbus Line SCXI 1121 Rear Signal Connector MIO 16 Lab Board PC LPM 16 MOSI SERDATIN ADIO0 PB4 DOUT4 D A DAQD A ADIO1 PB5 DOUT5 INTR SLOT0SEL ADIO2 PB6 DOUT6 SPICLK SERCLK EXTSTROBE PB7 DOUT7 MISO SERDATOUT BDIO0 PC1 DIN6 Chapter 5 Programming National Instruments Corporation 5 3 SCXI 1121 User Manual 3 For each bit starting with the MSB first bit 15 a SERDATIN bit to be sent These bits are the data that is being written
144. s pin is connected to the excitation channel 3 negative output A14 CH3 Positive Input Channel 3 This pin is connected to the input channel 3 positive input C14 CH3 Negative Input Channel 3 This pin is connected to the input channel 3 negative input A16 EGND2 Excitation Ground 2 This pin connects to the excitation ground 2 via a 51 k resistor A18 EX2 Positive Excitation Output 2 This pin is connected to the excitation channel 2 positive output Appendix D SCXI 1121 Front Connector SCXI 1121 User Manual D 4 www natinst com Further information is given in Chapter 2 Configuration and Installation C18 EX2 Negative Excitation Output 2 This pin is connected to the excitation channel 2 negative output A20 CH2 Positive Input Channel 2 This pin is connected to the input channel 2 positive input C20 CH2 Negative Input Channel 2 This pin is connected to the input channel 2 negative input A22 EGND1 Excitation Ground 1 This pin connects to the excitation ground 1 via a 51 k resistor A24 EX1 Positive Excitation Output 1 This pin is connected to the excitation channel 1 positive output C24 EX1 Negative Excitation Output 1 This pin is connected to the excitation channel 1 negative output A26 CH1 Positive Input Channel 1 This pin is connected to the input channel 1 positive input C26 CH1 Negative Input Channel 1 This pin is connected to the input c
145. slot extender in its rear connector space Follow these steps to install the SCXI 1180 1 Make sure that the computer and the SCXI chassis are turned off 2 Remove the front filler panel of the slot where you will insert the SCXI 1180 3 Thread the rear connector through the front of the chassis to the rear of the chassis Attach the rear connector to the breakout connector of the adjacent cable assembly or slot extender as shown in Figure E 2 Figure E 2 SCXI 1180 Rear Connections 4 Screw in the rear panel to the threaded strip in the rear of the chassis 5 Screw the front panel into the front threaded strip as shown in Figure E 3 Check the installation Step 3 SCXI 1180 Breakout Connector Ribbon Cable to Front Panel Rear Connector Breakout Connector from SCXI 1340 Threaded Strip in Rear of Chassis Step 4 Rear Panel Appendix E SCXI 1121 Cabling SCXI 1121 User Manual E 10 www natinst com Figure E 3 SCXI 1180 Front Panel Installation SCXI 1302 50 Pin Terminal Block The SCXI 1302 terminal block has screw terminal connections for the 50 pin connector on the SCXI 1180 feedthrough panel SCXI 1302 Wiring Procedure To wire the SCXI 1302 terminal block you must remove the cover connect all the wiring and replace the cover The procedure for this is as follows 1 Unscrew the rear grounding screw on the back of the terminal block as shown in Figure E 4 2 With a flathead scre
146. sor 1 SCXI 1320 and SCXI 1321 Accuracy 1 0 C over 0 to 55 C Output 10 mV C SCXI 1328 Accuracy2 0 35 from 15 to 35 C 0 65 from 0 to 15 and 35 to 55 C Output 1 91 to 0 58 V from 0 to 55 C Output at 25 C 1 25 V 1 Located on the SCXI 1320 SCXI 1328 and SCXI 1321 terminal blocks 2 Includes the combined effects of the temperature sensor accuracy and the temperature difference between the temperature sensor and any screw terminal Appendix A Specifications SCXI 1121 User Manual A 4 www natinst com Note You can find the temperature T C as follows T TK 273 15 where TK is the temperature in kelvin a 1 288 x 10 3 b 2 356 x 10 4 c 9 556 x 10 8 RT resistance of the thermistor in VTEMPOUT output voltage of the temperature sensor Physical Dimensions 1 2 by 6 8 by 8 0 in Connectors 50 pin male ribbon cable rear connector 32 pin DIN C front connector 18 screw terminal adapter available Environment Operating Temperature 0 to 50 C Storage Temperature 20 to 70 C Relative humidity
147. ssis The SCXI 1121 module is installed and ready for operation Chapter 2 Configuration and Installation National Instruments Corporation 2 15 SCXI 1121 User Manual Signal Connections This section describes the input and output signal connections to the SCXI 1121 board via the SCXI 1121 front connector and rear signal connector and includes specifications and connection instructions for the signals given on the SCXI 1121 connectors Cautions Do not operate the device in an explosive atmosphere or where there may be flammable gasses or fumes Keep away from live circuits Do not remove equipment covers or shields unless you are trained to do so If signal wires are connected to the device hazardous voltages may exist even when the equipment is turned off To avoid a shock hazard do not perform procedures involving cover or shield removal unless you are qualified to do so and disconnect all field power prior to removing covers or shields Equipment described in this document must be used in an Installation Category II environment per IEC 60664 This category requires local level supply mains connected installation Do not operate damaged equipment The safety protection features built into this device can become impaired if the device becomes damaged in any way If the device is damaged turn the device off and do not use until service trained personnel can check its safety If necessary return the device to National Instrumen
148. sts the maximum load that can be driven per channel at each level of excitation for both volt and current excitation Table 2 6 Voltage and Current Mode Excitation Jumper Setup Excitation Channel Jumpers Voltage Mode Factory Setting Current Mode 0 W14 and W15 1 W22 and W23 2 W34 and W35 3 W46 and W47 W14 1 2 3 W15 1 2 3 W14 1 2 3 W15 1 2 3 W22 1 2 3 W23 1 2 3 W22 1 2 3 W23 1 2 3 W34 1 2 3 W35 1 2 3 W34 1 2 3 W35 1 2 3 W46 1 2 3 W47 1 2 3 W46 1 2 3 W47 1 2 3 Chapter 2 Configuration and Installation National Instruments Corporation 2 11 SCXI 1121 User Manual After selecting the excitation mode of operation desired Voltage or Current as described in the previous section use Table 2 8 to set your SCXI 1121 for the level of operation Your SCXI 1121 is shipped with the Voltage mode set to 3 333 V Table 2 7 Maximum Load per Excitation Channel Excitation Level Maximum Load 3 333 V 28 mA 10 V 14 mA 0 150 mA 10 k 0 450 mA 10 k Table 2 8 Excitation Level Jumper Selection
149. sure that its output is not driving AB0 2 Write the binary pattern 10XXXXXX XX100011 to the SCXI 1121 Configuration Register This step disables the SCXI 1121 from driving Analog Bus 0 and allows Analog Bus 0 to drive MCH0 through the output buffer 3 Program the other module to be scanned Channel Scanning from the SCXI 1121 via Another Module To scan the SCXI 1121 via other modules you must cable the other module to a data acquisition board and the other module must be able to transfer Analog Bus 0 to the data acquisition board The other module must also be able to send a SCANCLK compatible signal on TRIG0 See Chapter 2 Configuration and Installation for more information The module programming steps are as follows 1 Perform any necessary programming to ensure that no modules are driving Analog Bus 0 For an SCXI 1121 clearing AB0EN in the Configuration Register will ensure that its output is not driving AB0 Chapter 5 Programming SCXI 1121 User Manual 5 12 www natinst com 2 Program the other module not to drive Analog Bus 0 but to send Analog Bus 0 to the data acquisition board Also program the other module to send a SCANCLK compatible signal to TRIG0 3 Write the binary pattern 01ScXXXCC XX001111 to the SCXI 1121 Configuration Register where CC is the starting channel number Multiple Module Multiplexed Scanning To scan multiple modules you must connect one module to the data acquisition board and t
150. ted in column A Their corresponding negative input channels are located in column C Each input corresponds to a separate amplifier and is fully isolated from the other channels and from earth ground The inputs are designed in a floating single ended configuration hence the measured signal can be referenced to a ground level with common mode voltage up to 250 Vrms For better noise immunity connect the negative input channel to the signal reference If the measured signals are floating connect the negative input channel to chassis ground on the terminal block Figure 2 4 shows how to connect a ground referenced signal Figure 2 5 shows how to connect a floating signal Figures 2 6 and 2 7 show how to connect AC coupled signals Figure 2 4 Ground Referenced Signal Connection with High Common Mode Voltage Figure 2 5 Floating Signal Connection Referenced to Chassis Ground for Better Signal to Noise Ratio Vs Vcm High CMV Vout Module Vs Vout Module Chapter 2 Configuration and Installation National Instruments Corporation 2 21 SCXI 1121 User Manual Figure 2 6 Floating AC Coupled Signal Connection Figure 2 7 AC Coupled Signal Connection with High Common Mode Voltage For AC coupled signals you should connect an external resistor from the positive input channel to the signal reference This is needed to provide the DC path for the positive input bias curre
151. ter 1 Mode Value for most MIO boards Write 1325 hex to the Am9513 Data Register to store Counter 1 Mode Value for the AT MIO 16F 5 AT MIO 64F 5 and AT MIO 16X boards 3 Write FF09 to the Am9513 Command Register to select Counter 1 Load Register 4 Write the number of samples to be taken per scan list entry 2 to 65 535 to the Am9513 Data Register to load Counter 1 5 Write FF41 to the Am9513 Command Register to load Counter 1 6 Write FFF1 to the Am9513 Command Register to step Counter 1 7 Write FF21 to the Am9513 Command Register to arm Counter 1 8 Set the SCANDIV bit in Command Register 1 2 Module Programming This section describes the programming steps for various scanning possibilities For all the bit patterns in this section Sc signifies the shunt calibration bit If you set this bit to one the module will be scanned in Shunt Calibration mode If you clear this bit to zero shunt calibration will be disabled on the module during scanning When programming a module to change the shunt calibration mode from disabled to enabled or vice versa insert a delay before you make any measurements If the SCXI 1121 has a filter setting at 10 kHz the delay should be at least 1 msec If the SCXI 1121 has the filter set at 4 Hz the delay should be at least 1 sec Single Module Parallel Scanning In order to perform single module parallel scanning you must cable the SCXI 1121 rear signal connector to a data acquisit
152. ter Descriptions for information on reading the Module ID Register See Appendix E SCXI 1121 Cabling for the pin equivalences of the SCXI 1121 rear signal connector and the data acquisition board I O connector This is the factory default setting Position 3 disconnects SERDATOUT from the SCXIbus MISO line Jumper W32 On Revision A and B modules jumper W32 should not be connected On Revision C or later modules Position 1 connects a 2 2 k pullup resistor to the SERDATOUT line factory default setting and Position 3 does not connect the pullup resistor to the SERDATOUT line Using Jumpers W32 and W38 Set jumpers W32 and W38 as follows If the SCXI 1121 is not cabled to a data acquisition board the positions of these jumpers do not matter so leave them in their factory default positions both in position 1 If the SCXI 1121 is cabled to a data acquisition board and the SCXI chassis that the SCXI 1121 is in is the only SCXI chassis cabled to that data acquisition board leave the jumpers in their factory default positions both in position 1 If the SCXI 1121 is cabled to a data acquisition board and there are multiple SCXI chassis cabled to that data acquisition board with shielded cables you are using SCXI 1346 shielded cable multi chassis adapters leave the jumpers in their factory default positions both in position 1 If the SCXI 1121 is cabled to a data acquisition board and there are multiple SCXI chassis cab
153. terval Counter Counter A0 You will do this after you program the modules and Slot 0 Counter 1 and SCANDIV All MIO boards can operate their data acquisition board scan lists in two ways they can acquire one sample per data acquisition board scan list entry or they can acquire N samples per data acquisition board scan list entry where N is a number from 2 to 65 535 that is programmed in Counter 1 This second method of operation is especially useful when the data acquisition board scan list length is limited to 16 entries as it is on all MIO boards except the AT MIO 16F 5 which can have up to 512 entries Because you can multiplex many SCXI 1121s in one chassis to one MIO board channel often the simplest way to program the MIO board is to use only one data acquisition board scan list entry and make N the total number of samples to be taken on all modules in one scan Check your MIO board user manual for limitations in the data acquisition board scan list format Chapter 5 Programming SCXI 1121 User Manual 5 10 www natinst com To program the MIO board to take N samples per data acquisition board scan list entry perform the following additional programming steps at the end of the Enable the Scanning Data Acquisition Operation section in the appropriate data acquisition board user manual 1 Write FF01 to the Am9513 Command Register to select Counter 1 Mode Register 2 Write 0325 hex to the Am9513 Data Register to store Coun
154. th the first scan list entry after the entry is finished 3 HSRS Hardscan Reset When clear this bit causes all the hardware scanning circuitry including the FIFO to be reset to the power up state When set this bit has no effect 2 LOAD Load This bit when clear forces a loading of the Slot 0 sample counter with the output of the FIFO When set this bit has no effect 7 6 5 4 3 2 1 0 RSVD FRT RD ONCE HSRS LOAD SCANCONEN CLKEN Chapter 4 Register Descriptions SCXI 1121 User Manual 4 8 www natinst com 1 SCANCONEN Scan Control Enable When set this bit enables the SCANCON lines When clear all SCANCON lines are disabled high 0 CLKEN Clock Enable When set this bit enables TRIG0 as a clock for the hardscan circuitry When clear TRIG0 is disabled Chapter 4 Register Descriptions National Instruments Corporation 4 9 SCXI 1121 User Manual FIFO Register The FIFO Register is used to add entries to the Slot 0 FIFO The FIFO contains the Slot 0 scan list Each entry contains a slot number to be accessed and a count number to determine the number of samples to be taken from that slot To write to the FIFO Register follow the procedure given in the Register Writes section of Chapter 5 Programming using 14 as the slot number and writing 16 bits to the FIFO Register The register will shift in the data present on the MOSI line bit 15 first when Slot 14 is selected by the Slot Select
155. the other module not to drive Analog Bus 0 but to send Analog Bus 0 to the data acquisition board 3 Write the binary pattern 001XXXCC XX000010 to the SCXI 1121 Configuration Register 4 Insert a delay equal to 1 sec if you have set the 4 Hz filter or 1 msec if you have set the 10 kHz filter This delay permits the SCXI 1121 amplifier to settle 5 Measure the voltage with the data acquisition board To measure the voltage on the MTEMP line perform the following steps 1 Perform any necessary programming to ensure that no modules are driving Analog Bus 0 For an SCXI 1121 clearing AB0EN in the Configuration Register will ensure that its output is not driving AB0 2 Program the other module not to drive Analog Bus 0 but to send Analog Bus 0 to the data acquisition board 3 Write the binary pattern 000XXXXX XX100010 to the SCXI 1121 Configuration Register 4 Measure the voltage with the data acquisition board Chapter 5 Programming National Instruments Corporation 5 7 SCXI 1121 User Manual Scanning Measurements Programming for scanned data acquisition involves programming your data acquisition board modules and Slot 0 In general the steps to be taken are as follows 1 Perform all data acquisition board programming to the point of enabling the data acquisition 2 Perform all module programming 3 Program the Slot 0 hardscan circuitry 4 Enable the data acquisition trigger it either th
156. the temperature use the following formulas where VTEMPOUT is the temperature sensor output and T F and T C are the temperature readings in degrees Fahrenheit and degrees Celsius respectively The SCXI 1328 temperature sensor outputs 0 62 to 0 07 V from 0 to 55 C and has an accuracy of 0 35 C over the 15 to 35 C range and 0 65 C over the 0 to 15 C and 35 to 55 C ranges To determine the temperature use the following formulas where TK is the temperature in kelvin T C 100 VTEMPOUT T F T C 9 5 32 T C TK 273 15 Chapter 2 Configuration and Installation National Instruments Corporation 2 31 SCXI 1121 User Manual a 1 288 x 10 3 b 2 356 x 10 4 c 9 556 x 10 8 RT resistance of the thermistor in VTEMPOUT output voltage of the temperature sensor where T F and T C are the temperature readings in degrees Fahrenheit and degrees Celsius respectively Terminal Block Jumper Configuration In addition to the screw terminals the terminal block has one jumper for configuring the onboard temperature sensor When you set jumper W1 on the SCXI 1320 or SCXI 1328 jumper W5 on the SCXI 1321 to the MTEMP position the jumper connects the temperature sensor output to the SCXI 1121 output multiplexer This is the factory setting The DTEMP position of jumper W1 jumper W5 on the SCXI 1321 conn
157. ting another slot write zero to the Slot 0 Slot Select Register If you are selecting another slot start at step 3 For a timing illustration of a Configuration Register write see Figure 2 18 Configuration Register Write Timing Diagram which shows the proper write to configure an SCXI 1121 that is directly cabled to an MIO 16 for multiple module multiplexed scanning with a start channel of 3 Initialization The SCXI 1121 powers up with its Configuration register cleared to all zeros You can force this state by an active low signal on the RESET pin of the backplane connector In the reset state CH0 through CH3 are routed Chapter 5 Programming SCXI 1121 User Manual 5 4 www natinst com to MCH0 through MCH3 on the rear signal connector The module is disconnected from Analog Bus 0 and disabled from scanning Single Channel Measurements This section describes how to program the SCXI 1121 either alone or in conjunction with other modules to make single channel or nonscanned measurements Direct Measurements Parallel Output In order to perform a parallel output measurement you must cable the SCXI 1121 rear signal connector to a data acquisition board with each output connected to a different data acquisition board channel See Chapter 2 Configuration and Installation for more information For information on how to make the voltage measurement with your data acquisition board consult your data acquisition board user ma
158. to excitation channel 0 Each excitation channel consists of a voltage current source with overvoltage protection and current limiting Two levels of excitation are available for each mode of operation In the voltage mode you can set the level to 3 333 V or 10 V in the current mode you can set the level to 150 A or 450 A You can choose one configuration out of the four available To configure the excitation channels refer to Chapter 2 Configuration and Installation The excitation channels are isolated from each other and are independently configurable for voltage or current excitation Calibration Calibration Equipment Requirements For best measurement results calibrate the SCXI 1121 so that its offset is adjusted to 0 3 mV RTO and 0 6 V RTI and its excitation output is adjusted to 0 04 According to standard practice the equipment used to calibrate the SCXI 1121 should be 10 times as accurate as the SCXI 1121 that is have 0 004 rated accuracy Practically speaking calibration equipment with four times the accuracy of the item under calibration is generally considered acceptable Four times the SCXI 1121 accuracy is 0 016 To calibrate the SCXI 1121 you need the following equipment For the excitation channels you need a voltmeter with the following specifications Accuracy 0 004 standard 0 016 sufficient Range 0 to 5 V for 3 333 V and greater than 10 V for 10 V Resolution 5 1 2 d
159. to the mounting bracket is a 50 pin female mounting bracket connector that connects to the module rear signal connector To extend the signals of the MIO 16 board to an SCXI 1180 feedthrough panel or an SCXI 1181 breadboard module you can use the male breakout connector that is near the mounting bracket on the ribbon cable All 50 pins from the MIO 16 board go straight through to the rear signal connector Appendix E SCXI 1121 Cabling SCXI 1121 User Manual E 2 www natinst com You can use a standard 50 pin ribbon cable instead of the SCXI 1340 cable assembly The SCXI 1340 has the following advantages over the ribbon cable The SCXI 1340 has strain relief so that you cannot accidentally disconnect the cable The SCXI 1340 includes a mounting bracket that mounts to the chassis so that you can remove and reinsert the module without explicitly removing the cable from the back of the chassis This is especially useful when the SCXI chassis is rack mounted making rear access difficult The SCXI 1340 has an extra male breakout connector for use with the SCXI 1180 feedthrough panel or additional modules or breadboards that need a direct connection to the MIO 16 board The SCXI 1340 rear panel gives the module and the chassis both mechanical and electrical shielding Table E 1 lists the pin equivalences of the MIO 16 and the SCXI 1121 Table E 1 SCXI 1121 and MIO 16 Pinout Equivalences Pin SCXI 1121 Rear Signa
160. tor Make sure a corner of the adapter board enters the upper board guide of the chassis 6 Screw the rear panel to the threaded strips in the rear of the chassis Table E 4 SCXI 1343 Pin Connections Rear Signal Connector Pin SCXI 1121 Use Connection Type 1 AOGND Solder pad 2 AOGND Screw terminal 3 MCH0 Screw terminal 4 MCH0 Screw terminal 5 MCH1 Screw terminal 6 MCH1 Screw terminal 7 MCH2 Screw terminal 8 MCH2 Screw terminal 9 MCH3 Screw terminal 10 MCH3 Screw terminal 11 MCH4 Screw terminal Appendix E SCXI 1121 Cabling National Instruments Corporation E 15 SCXI 1121 User Manual 12 MCH4 Screw terminal 13 No Connect Screw terminal 14 No Connect Screw terminal 15 No Connect Screw terminal 16 No Connect Screw terminal 17 No Connect Screw terminal 18 No Connect Screw terminal 19 OUTREF Screw terminal 20 No Connect Solder pad 21 No Connect Solder pad 22 No Connect Solder pad 23 No Connect Solder pad 24 33 DIG GND Solder pad 26 SERDATOUT Solder pad 27 DAQD A Solder pad 28 No Connect Solder pad 29 SLOT0SEL Solder pad 30 No Connect Solder pad 31 No Connect Solder pad 32 No Connect Solder pad 33 No Connect Solder pad 34 35 No Connect Solder pad 36 SCANCLK Solder pad 37 SERCLK Solder pad 38 No Connect Solder pad Table E 4 SCXI 1343 Pin Connections Conti
161. ts for service and repair to ensure that its safety is not compromised Do not operate this equipment in a manner that contradicts the information specified in this document Misuse of this equipment could result in a shock hazard Terminals are for use only with equipment that has no accessible live parts Do not substitute parts or modify equipment Because of the danger of introducing additional hazards do not install unauthorized parts or modify the device Return the device to National Instruments for service and repair to ensure that its safety features are not compromised When using the device with high common mode voltages you must insulate your signal wires for the highest input voltage National Instruments is not liable for any damages or injuries resulting from inadequate signal wire insulation Use only 26 14 AWG wire with a voltage rating of 300 V and 60 C for measuring 250 V Prepare your signal wire by stripping the insulation no more than 7 mm Chapter 2 Configuration and Installation SCXI 1121 User Manual 2 16 www natinst com When connecting or disconnecting signal lines to the SCXI terminal block screw terminals make sure the lines are powered off Potential differences between the lines and the SCXI ground create a shock hazard while you connect the lines Connect the signal wires to the screw terminals by inserting the stripped end of the wire fully into the terminals Tighten the terminals to a torque of 5 to
162. ts of a multichassis adapter board You will also need a ribbon cable for each chassis to chassis connection as well as a ribbon cable to connect the MIO board to the first chassis Note Use 0 5 m ribbon cable when connecting multiple chassis together to minimize cable length and maintain signal integrity You can use a 1 m cable to connect the MIO board to the first chassis Appendix E SCXI 1121 Cabling National Instruments Corporation E 13 SCXI 1121 User Manual The adapter board has a male rear connector a female front connector and a male chassis extender connector You can attach the rear connector to a ribbon cable from the MIO board or a preceding chassis You connect the front connector with the module rear signal connector You connect the chassis extender connector to a ribbon cable that goes to the subsequent chassis The adapter takes Channel 0 from the front connector and sends it to Channel 0 of the rear connector The adapter also takes channels 0 through 6 on the chassis extender connector and maps them to channels 1 through 7 respectively on the rear connector SCXI 1350 Installation Follow these steps to install the SCXI 1350 1 Make sure that the computer and all the SCXI chassis are turned off 2 Insert all the modules in all the chassis 3 Connect one end of a ribbon cable to the MIO board 4 Connect the other end of the ribbon cable to the rear connector of the first SCXI 1350 5 Connect
163. up or at reset amplifier channel 0 is selected on the output multiplexer and hence connects to MCH0 The other four channels three amplifier channels and one temperature channel are hardwired to the rear signal connector Notice that even when you select the Multiplexed Output mode the SCXI 1121 drives the rear signal connector pins 5 through 12 The SCXI 1121 outputs on the rear signal connector are short circuit protected Refer to the following Scanning Modes section for further details on how to scan the SCXI 1121 channels Chapter 3 Theory of Operation National Instruments Corporation 3 17 SCXI 1121 User Manual Scanning Modes There are four basic types of scanning modes possible with the SCXI 1121 single module parallel scanning single module multiplexed scanning multiple module multiplexed scanning and multiple chassis scanning possible only with the SCXI 1001 chassis For additional information consult Chapter 2 Configuration and Installation Chapter 5 Programming your data acquisition board manual and your SCXI chassis user manual If you need further information contact National Instruments Single Module Parallel Scanning Single Module parallel scanning is the simplest scanning mode Directly cable the SCXI 1121 to the data acquisition board as shown in Figure 3 7 In this configuration each analog signal has its own channel Timing signals are not necessary for this type of scanning because the module
164. vision 3M part number 3425 7650 T amp B Ansley Corporation part number 609 5041CE Standard 50 conductor 28 AWG stranded ribbon cables that can be used with these connectors are as follows Electronic Products Division 3M part number 3365 50 T amp B Ansley Corporation part number 171 50 The SCXI 1121 front connector is a 32 pin DIN C male connector with column A and column C even pins only The manufacturer part number used by National Instruments for this connector is as follows Panduit Corporation part number 100 932 023 The mating connector for the SCXI 1121 front connector is a 32 pin DIN C female connector National Instruments uses a polarized connector to prevent inadvertent upside down connection to the SCXI 1121 Recommended manufacturer part numbers for this mating connector are as follows Panduit Corporation part number 100 932 434 straight solder eyelet pins Panduit Corporation part number 100 932 633 right angle pins National Instruments selected these connectors to meet UL 1950 and UL 1244 for 1 500 Vrms isolation Chapter 1 Introduction SCXI 1121 User Manual 1 6 www natinst com Unpacking Your SCXI 1121 module is shipped in an antistatic package to prevent electrostatic damage to the module Several components on the module can be damaged by electrostatic discharge To avoid such damage in handling the module take the following precautions Touch the
165. wdriver carefully pry the cover off the terminal block 3 Insert each wire through the terminal block strain relief opening 4 Connect the wires to the screw terminals 5 Tighten the large strain relief screws to secure the wires Front Panel Connector Front Panel Front Threaded Strip Ribbon Cable to Rear and Breakout Connectors Step 5 Appendix E SCXI 1121 Cabling National Instruments Corporation E 11 SCXI 1121 User Manual 6 Snap the cover back in place 7 Reinsert the rear grounding screw The terminal block is now ready to be connected to the front panel connector Figure E 4 Cover Removal SCXI 1302 Installation Follow these steps to install the SCXI 1302 1 Install an SCXI 1180 feedthrough panel as described in the SCXI 1180 Installation section 2 Wire the terminal block as described in the SCXI 1302 Wiring Procedure section 3 Connect the SCXI 1302 terminal block to the front panel connector on the SCXI 1180 feedthrough panel Be careful to fit the thumbscrews in the thumbscrew cutouts 4 Tighten the top and bottom captive screws on the back of the terminal block into the screw holes in the front panel This will hold the SCXI 1302 securely in place 5 Check the installation 50 Pin Connector Grounding Screw Thumbscrew Cutout Step 1 Step 2 Insert Screwdriver in Groove and Rotate to Pry Open Appendix E SCXI 1121 Cabling SCXI 1121 User Manual E 12
166. x E SCXI 1121 Cabling Appendix F Revision A and B Photo and Parts Locator Diagrams Appendix G Technical Support Resources Glossary Index Contents SCXI 1121 User Manual viii www natinst com Figures Figure 2 1 SCXI 1121 General Parts Locator Diagram 2 2 Figure 2 2 SCXI 1121 Detailed Parts Locator Diagram 2 3 Figure 2 3 SCXI 1121 Front Connector Pin Assignment 2 18 Figure 2 4 Ground Referenced Signal Connection with High Common Mode Voltage 2 21 Figure 2 5 Floating Signal Connection Referenced to Chassis Ground for Better Signal to Noise Ratio 2 21 Figure 2 6 Floating AC Coupled Signal Connection 2 22 Figure 2 7 AC Coupled Signal Connection with High Common Mode Voltage 2 22 Figure 2 8 Assembling and Mounting the SCXI 1330 Connector and Shell Assembly 2 25 Figure 2 9 Nulling Circuit 2 29 Figure 2 10 Shunt Circuit 2 30 Figure 2 11 SCXI 1320 Parts Locator Diagram
167. xcitation voltage potentiometer until you read 3 333 V 0 04 5 Set up your channel for 150 A excitation level 6 Adjust the excitation current potentiometer until you read 150 A x R120 V 0 04 where R120 is the measured value of the precision resistor 7 Go to the next channel If you are using an ammeter to calibrate the current excitation level you do not need a low tempco resistor a simple 120 1 1 4 W 100 ppm metal film resistor will do and you do not need to measure the resistor After following the previous procedure through step 4 follow these steps 1 Remove the resistor from the excitation channel 2 Set up your channel for 150 A excitation level 3 Connect the ammeter leads to the excitation channel output 4 Adjust the excitation current potentiometer until you read 150 A 0 04 5 Go to the next channel Chapter 3 Theory of Operation SCXI 1121 User Manual 3 14 www natinst com This procedure calibrates the 10 V and 450 A levels at the same time but the accuracy achieved is limited to 0 2 To achieve better accuracies at these levels follow the procedure indicated above but set the excitation levels to 10 V and to 450 A instead of 3 333 V and 150 A If you do so the lower excitation levels of this channel will then be calibrated to 0 2 instead of to 0 04 In the factory the module is calibrated for 3 333 V and 150 A You can seal the potentiometers
168. year from the date of shipment as evidenced by receipts or other documentation National Instruments will at its option repair or replace equipment that proves to be defective during the warranty period This warranty includes parts and labor A Return Material Authorization RMA number must be obtained from the factory and clearly marked on the outside of the package before any equipment will be accepted for warranty work National Instruments will pay the shipping costs of returning to the owner parts which are covered by warranty National Instruments believes that the information in this document is accurate The document has been carefully reviewed for technical accuracy In the event that technical or typographical errors exist National Instruments reserves the right to make changes to subsequent editions of this document without prior notice to holders of this edition The reader should consult National Instruments if errors are suspected In no event shall National Instruments be liable for any damages arising out of or related to this document or the information contained in it EXCEPT AS SPECIFIED HEREIN NATIONAL INSTRUMENTS MAKES NO WARRANTIES EXPRESS OR IMPLIED AND SPECIFICALLY DISCLAIMS ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE CUSTOMER S RIGHT TO RECOVER DAMAGES CAUSED BY FAULT OR NEGLIGENCE ON THE PART OF NATIONAL INSTRUMENTS SHALL BE LIMITED TO THE AMOUNT THERETOFORE PAID BY THE CUSTOMER NATIONAL INSTRUMENTS

National Instruments SCXI-1121 User's Manual

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