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National Instruments SCXI-1121 User Manual

National Instruments SCXI-1121 User Manual

Four-channel isolated universal transducer module for signal conditioning
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SCXI-1121
User Manual
Four-Channel Isolated Universal Transducer Module for Signal Conditioning
August 1994 Edition
Part Number 320426B-01
© Copyright 1992, 1994 National Instruments Corporation.
All Rights Reserved.

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  • Page 1 SCXI-1121 User Manual Four-Channel Isolated Universal Transducer Module for Signal Conditioning August 1994 Edition Part Number 320426B-01 © Copyright 1992, 1994 National Instruments Corporation. All Rights Reserved.
  • Page 2 National Instruments Corporate Headquarters 6504 Bridge Point Parkway Austin, TX 78730-5039 (512) 794-0100 Technical support fax: (800) 328-2203 (512) 794-5678 Branch Offices: Australia (03) 879 9422, Austria (0662) 435986, Belgium 02/757.00.20, Canada (Ontario) (519) 622-9310, Canada (Québec) (514) 694-8521, Denmark 45 76 26 00, Finland (90) 527 2321, France (1) 48 14 24 24, Germany 089/741 31 30, Italy 02/48301892, Japan (03) 3788-1921, Netherlands 03480-33466, Norway 32-848400, Spain (91) 640 0085, Sweden 08-730 49 70, Switzerland 056/20 51 51, U.K.
  • Page 3 Limited Warranty The SCXI-1121 is warranted against defects in materials and workmanship for a period of one 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.
  • Page 4 Any use or application of National Instruments products for or involving medical or clinical treatment must be performed by properly trained and qualified medical personnel, and all traditional medical safeguards, equipment, and procedures that are appropriate in the particular situation to prevent serious injury or death should always continue to be used when National Instruments products are being used.

  • Page 5: Table Of Contents

    Terminal Block ................2-21 SCXI-1321 Nulling Circuitry......... 2-21 Using the SCXI-1321 with RTDs and Thermistors ..2-23 SCXI-1321 Shunt Calibration ........2-24 Terminal Block Temperature Sensor ......... 2-26 Terminal Block Jumper Configuration ........2-27 © National Instruments Corporation SCXI-1121 User Manual...
  • Page 6 Chapter 4 Register Descriptions ......................4-1 Register Description....................... 4-1 Register Description Format ................4-1 SCXI-1121 Registers ..................4-1 Module ID Register................4-2 Configuration Register ................4-3 Slot 0 Register Descriptions................4-5 Slot-Select Register ................4-6 Hardscan Control Register (HSCR) ............4-7 FIFO Register..................
  • Page 7 Multiplexed Output ..............5-3 Indirect Measurements ................5-4 Measurements from Other Modules .......... 5-4 Measurements from the SCXI-1121 via Another Module ..5-5 Scanning Measurements ..................5-6 1. Data Acquisition Board Setup Programming........5-6 Counter 1 and SCANDIV ............5-8 2.
  • Page 8 SCXI-1343 Rear Screw Terminal Adapter ..............E SCXI-1343 Installation ..................E Appendix F Revision A and B Photo and Parts Locator Diagrams ......... F-1 Appendix G Customer Communication ....................G-1 Glossary ........................Glossary-1 Index ..........................Index-1 SCXI-1121 User Manual viii © National Instruments Corporation...
  • Page 9 Figure 2-12. SCXI-1328 Parts Locator Diagram ..............2-30 Figure 2-13. SCXI-1321 Parts Locator Diagram ..............2-31 Figure 2-14. SCXI-1121 Rear Signal Connector Pin Assignment ......... 2-33 Figure 2-15. SCANCLK Timing Requirements ..............2-37 Figure 2-16. Slot-Select Timing Diagram ................2-38 Figure 2-17.
  • Page 10 Table 2-14. Jumper Settings on the SCXI-1328 Terminal Block ......... 2-27 Table 2-15. Jumper Settings on the SCXI-1321 Terminal Block ......... 2-28 Table 2-16. SCXIbus to SCXI-1121 Rear Signal Connector to Data Acquisition Board Pin Equivalences ....................2-36 Table 3-1.

  • Page 11: About This 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.

  • Page 12: Conventions Used In This Manual

    About This Manual • Appendix F, Revision A and B Photo and Parts Locator Diagrams, contains a photograph of the Revision A and B SCXI-1121 signal conditioning module and the general and detailed parts locator diagrams. • Appendix G, Customer Communication, contains forms you can use to request help from National Instruments or to comment on our products.

  • Page 13: Related Documentation

    SCXI-1000/1001 User Manual (part number 320423-01) Customer Communication National Instruments wants to receive your comments on our products and manuals. We are interested in the applications you develop with our products, and we want to help if you have problems with them. To make it easy for you to contact us, this manual contains comment and configuration forms for you to complete.

  • Page 14: Chapter 1 Introduction

    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 Installation. You can multiplex several SCXI-1121s into a single channel, thus greatly increasing the number of analog input signals that can be digitized.

  • Page 15: 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.

  • Page 16: Optional Equipment

    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: •...

  • Page 17: Unpacking

    • T&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: •...

  • Page 18: 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. © National Instruments Corporation...

  • Page 19: Figure 2-1. Scxi-1121 General Parts Locator Diagram

    Configuration and Installation Chapter 2 Figure 2-1. SCXI-1121 General Parts Locator Diagram SCXI-1121 User Manual © National Instruments Corporation...

  • Page 20: Figure 2-2. Scxi-1121 Detailed Parts Locator Diagram

    Chapter 2 Configuration and Installation Figure 2-2. SCXI-1121 Detailed Parts Locator Diagram © National Instruments Corporation SCXI-1121 User Manual...

  • Page 21: Digital Signal Connections

    Further configuration of the board is software 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. SCXI-1121 User Manual...

  • Page 22: Jumper W44

    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).

  • Page 23: Table 2-1. Digital Signal Connections, Jumper Settings

    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.

  • Page 24: Analog Configuration

    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.

  • Page 25: Input Channel Jumpers

    1, 2, 5, 10, and 20. Tables 2-3 and 2-4 show how to set up the gain for each channel. Table 2-3. Gain Jumper Allocation Input Channel Number First Gain Jumper Second Gain Jumper SCXI-1121 User Manual © National Instruments Corporation...

  • Page 26: Filter Jumpers

    W31-A W31-B W43-A W43-B 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. © National Instruments Corporation SCXI-1121 User Manual...

  • Page 27: Excitation Jumpers

    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 2-6. Voltage and Current Mode Excitation Jumper Setup...

  • Page 28: Using The Internal Half-Bridge Completion

    Configuration and Installation 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.

  • Page 29: Hardware Installation

    • Hardware Installation You can install the SCXI-1121 in any available SCXI chassis. After you have made any necessary changes and have verified and recorded the jumper settings on the form in Appendix G, Customer Communication, you are ready to install the SCXI-1121. The following are general installation instructions;...

  • Page 30: Signal Connections

    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.

  • Page 31: Figure 2-3. Scxi-1121 Front Connector Pin Assignment

    EX0+ EGND0 CH1+ CH1- EX1+ EX1- EGND1 CH2+ CH2- EX2+ EX2- EGND2 CH3+ CH3- EX3+ EX3- EGND3 RSVD SCAL RSVD +5 V MTEMP CGND DTEMP Figure 2-3. SCXI-1121 Front Connector Pin Assignment SCXI-1121 User Manual 2-14 © National Instruments Corporation...

  • Page 32: Front Connector Signal Descriptions

    Negative Input Channel 3 – This pin is connected to the input channel 3 negative input. EGND2 Excitation Ground 2 – This pin connects to the excitation ground 2 via a 51 kΩ resistor. © National Instruments Corporation 2-15 SCXI-1121 User Manual...
  • Page 33 Positive Input Channel 0 – This pin is connected to the input channel 0 positive input. CH0- Negative Input Channel 0 – This pin is connected to the input channel 0 negative input. SCXI-1121 User Manual 2-16 © National Instruments Corporation...

  • Page 34: Analog Input Channels

    AC-coupled signals. Vout High Module Figure 2-4. Ground-Referenced Signal Connection with High Common-Mode Voltage Vout Module Figure 2-5. Floating Signal Connection Referenced to Chassis Ground for Better Signal-to-Noise Ratio © National Instruments Corporation 2-17 SCXI-1121 User Manual...

  • Page 35: Figure 2-6. Floating Ac-Coupled Signal Connection

    The input signal range of an SCXI-1121 input channel is ±5 V/ G referenced to its negative total input, where G is equal to the product of the first-stage and second-stage gains. In addition,...

  • Page 36: Excitation Channels

    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.

  • Page 37: Figure 2-8. Assembling And Mounting The Scxi-1330 Connector-And-Shell Assembly

    Configuration and Installation Chapter 2 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.

  • Page 38: Scxi-1320, Scxi-1328, And Scxi-1321 Terminal Blocks

    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.

  • Page 39: Table 2-10. Trimmer Potentiometer And Corresponding Channel

    (3.333 or 10 V). SCXI-1121 User Manual 2-22 © National Instruments Corporation...

  • Page 40: Using The Scxi-1321 With Rtds And Thermistors

    Using the SCXI-1321 with RTDs and Thermistors. When using this terminal block with 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.

  • Page 41: Table 2-12. Jumper Settings Of The Nulling Circuits

    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.

  • Page 42: Figure 2-10. Shunt Circuit

    = 3.333 V and R = 120 Ω produces the following result: = 0.3321 mV change Replacing the strained voltage with V in the quarter-bridge strain equation produces an change ε equivalent -199 µ of change. © National Instruments Corporation 2-25 SCXI-1121 User Manual...

  • Page 43: Terminal Block Temperature Sensor

    Configuration and Installation Chapter 2 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.

  • Page 44: Terminal Block Jumper Configuration

    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.

  • Page 45: Terminal Block Signal Connection

    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. SCXI-1121 User Manual 2-28 ©...

  • Page 46: Figure 2-11. Scxi-1320 Parts Locator Diagram

    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. Figure 2-11. SCXI-1320 Parts Locator Diagram © National Instruments Corporation 2-29 SCXI-1121 User Manual...

  • Page 47: Figure 2-12. Scxi-1328 Parts Locator Diagram

    Configuration and Installation Chapter 2 Figure 2-12. SCXI-1328 Parts Locator Diagram SCXI-1121 User Manual 2-30 © National Instruments Corporation...

  • Page 48: Figure 2-13. Scxi-1321 Parts Locator Diagram

    Chapter 2 Configuration and Installation Figure 2-13. SCXI-1321 Parts Locator Diagram © National Instruments Corporation 2-31 SCXI-1121 User Manual...

  • Page 49: 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.

  • Page 50: Figure 2-14. Scxi-1121 Rear Signal Connector Pin Assignment

    31 32 DIG GND 33 34 35 36 SCANCLK SERCLK 37 38 39 40 41 42 RSVD 43 44 45 46 47 48 49 50 Figure 2-14. SCXI-1121 Rear Signal Connector Pin Assignment © National Instruments Corporation 2-33 SCXI-1121 User Manual...

  • Page 51: Rear Signal Connector Signal Descriptions

    INTR* line to indicate whether the information on MOSI is being sent to a module or Slot 0. 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...

  • Page 52: Analog Output Signal Connections

    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.

  • Page 53: Table 2-16. Scxibus To Scxi-1121 Rear Signal Connector To Data Acquisition Board Pin Equivalences

    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 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.

  • Page 54: Timing Requirements And Communication Protocol

    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. © National Instruments Corporation 2-37 SCXI-1121 User Manual...

  • Page 55: Figure 2-16. Slot-Select Timing Diagram

    0 be written to the Slot-Select Register to ensure that no accidental writes occur. Figure 2-17 shows the timing requirements on the SERCLK and SERDATIN signals. You must observe these timing requirements for all communications. T is a specification of the delay SCXI-1121. SCXI-1121 User Manual 2-38 © National Instruments Corporation...

  • Page 56: Figure 2-17. Serial Data Timing Diagram

    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 ID Register, further data will be zeros until reinitialization occurs.

  • Page 57: Figure 2-18. Configuration Register Write Timing Diagram

    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 2-19 illustrates a read of the SCXI-1121 Module ID Register. SLOT0SEL* SERCLK...

  • Page 58: Chapter 3 Theory Of Operation

    Chapter 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 functional components of the SCXI-1121.

  • Page 59: Scxibus Connector

    • 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.

  • Page 60: Figure 3-2. Scxibus Connector Pin Assignment

    GUARD GUARD GUARD GUARD GUARD CHSGND CHSGND CHSGND CHSGND CHSGND RSVD RESET* INTR* D*/A MISO CHSGND CHSGND CHSGND CHSGND +5 V +5 V MOSI SPICLK TRIG0 SCANCON Figure 3-2. SCXIbus Connector Pin Assignment © National Instruments Corporation SCXI-1121 User Manual...

  • Page 61: Scxibus Connector Signal Descriptions

    Serial Peripheral Interface (SPI) Clock – Clocks the serial data on the MOSI and MISO lines. Open collector. I/O. MOSI Master-Out Slave-In – Transmits data from the SCXIbus to the module. Open collector. I/O. SCXI-1121 User Manual © National Instruments Corporation...

  • Page 62: Table 3-1. Scxibus Equivalents For The Rear Signal Connector

    Jumper W38 must be set to position 1 The SCXI-1121 module converts 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.

  • Page 63: Digital Interface

    The digital interface circuitry is divided into a data acquisition section and an SCXIbus section. The SCXI-1121 connects to the SCXIbus via a 4x24 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.

  • Page 64: Digital Control Circuitry

    (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 before being routed to the rest of the module. The channel-select bits are taken directly from the shift register.

  • Page 65: Analog And Timing Circuitry

    The SCXI-1121 module ID is hex 00000002. Analog and Timing Circuitry The SCXIbus 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.

  • Page 66: Figure 3-5. Analog Input Block Diagram

    Theory of Operation Input Channel 0 To Output Stage Input Channel 1 To Output Stage Input Channel 2 To Output Stage Input Channel 3 To Output Stage MTEMP DTEMP Figure 3-5. Analog Input Block Diagram © National Instruments Corporation SCXI-1121 User Manual...

  • Page 67: Excitation Output Channels

    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.

  • Page 68: Calibration

    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 µV 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.

  • Page 69: Offset Null Adjust

    6. Adjust the excitation current potentiometer until you read (150 µA x R ) V ± 0.04%, where is the measured value of the precision resistor. 7. Go to the next channel. SCXI-1121 User Manual 3-12 © National Instruments Corporation...

  • Page 70: Table 3-2. Calibration Potentiometer Reference Designators

    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. © National Instruments Corporation 3-13 SCXI-1121 User Manual...

  • Page 71: Analog Output Circuitry

    MCH4- 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 MCH0.

  • Page 72: Scanning Modes

    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.

  • Page 73: Multiplexed Scanning

    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 entry.

  • Page 74: Single-Module Multiplexed Scanning (Indirect)

    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.

  • Page 75: Multiple-Chassis Scanning

    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. Multichassis...

  • Page 76: Register Descriptions

    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.

  • Page 77: Module Id Register

    Chapter 4 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 the 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.

  • Page 78: Configuration Register

    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.
  • Page 79 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. SCXI-1121 User Manual © National Instruments Corporation...

  • Page 80: Slot 0 Register Descriptions

    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. © National Instruments Corporation SCXI-1121 User Manual...

  • Page 81: Slot-Select Register

    Chassis Bit 4 through 0 – These bits determine which chassis is selected. On the SCXI-1000 chassis, these bits are don't cares. SL<3..0> Slot Bit 3 through 0 – These bits determine which slot in the selected chassis is selected. SCXI-1121 User Manual © National Instruments Corporation...

  • Page 82: Hardscan Control Register (Hscr)

    Scan Control Enable – When set, this bit enables the SCANCON lines. When clear, all SCANCON lines are disabled (high). CLKEN Clock Enable – When set, this bit enables TRIG0 as a clock for the hardscan circuitry. When clear, TRIG0 is disabled. © National Instruments Corporation SCXI-1121 User Manual...

  • Page 83: Fifo Register

    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. SCXI-1121 User Manual © National Instruments Corporation...

  • Page 84: Chapter 5 Programming

    Chapter 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.

  • Page 85: Register Selection And Write Procedure

    Programming Chapter 5 Table 5-1. SCXI-1121 Rear Signal Connector Pin Equivalences SCXIbus Line SCXI-1121 MIO-16 Lab Board PC-LPM-16 Rear Signal Connector MOSI SERDATIN ADIO0 DOUT4 D*/A DAQD*/A ADIO1 DOUT5 INTR* SLOT0SEL* ADIO2 DOUT6 SPICLK SERCLK EXTSTROBE* DOUT7 MISO SERDATOUT BDIO0...

  • Page 86: Initialization

    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.

  • Page 87: Indirect Measurements

    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 buffer. 3. Program the other module to drive Analog Bus 0 with the signal to be measured.

  • Page 88: Measurements From The Scxi-1121 Via Another Module

    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.

  • Page 89: Scanning Measurements

    Posttrigger Data Acquisition with Interval Channel Scanning • AT-MIO-16X User Manual Continuous Channel Scanning Data Acquisition Interval Channel Scanning Data Acquisition • AT-MIO-64F-5 User Manual Continuous Channel Scanning Data Acquisition Interval Channel Scanning Data Acquisition SCXI-1121 User Manual © National Instruments Corporation...
  • Page 90 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. © National Instruments Corporation SCXI-1121 User Manual...

  • Page 91: Counter 1 And Scandiv

    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. SCXI-1121 User Manual © National Instruments Corporation...

  • Page 92: Module Programming

    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...

  • Page 93: Channel Scanning From The Scxi-1121 Via Another Module

    10S c XXXCC 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.

  • Page 94: Multiple-Chassis Scanning

    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 Circuitry The following section describes how to program the Slot 0 circuitry for scanning operations.

  • Page 95: Acquisition Enable, Triggering, And Servicing

    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.

  • Page 96: Scanning Examples

    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.

  • Page 97: Example 3

    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.
  • Page 98 11. 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. © National Instruments Corporation 5-15 SCXI-1121 User Manual...

  • Page 99: Appendix A Specifications

    Appendix 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 ±5 V...

  • Page 100: Rtd Mode

    Bridge completion Includes the combined effects of gain, offset, and hysteresis and nonlinearity Includes the combined effects of the SCXI-1121 and the AT-MIO-16F-5 Module tested following the UL 1244 standard to twice the working voltage +1000 Vrms SCXI-1121 User Manual...

  • Page 101: Cold-Junction Sensor

    (18-screw terminal adapter available) Located on the SCXI-1320, SCXI-1328, and SCXI-1321 terminal blocks Includes the combined effects of the temperature sensor accuracy and the temperature difference between the temperature sensor and any screw terminal © National Instruments Corporation SCXI-1121 User Manual...

  • Page 102: Operating Environment

    Operating Environment Temperature 0 to 50° C Relative humidity 5% to 90% at 35° C Storage Environment Temperature -55° to 150° C -55° to 125° C for SCXI-1328 Relative humidity 5% to 90% noncondensing SCXI-1121 User Manual © National Instruments Corporation...

  • Page 103: Appendix B Rear Signal Connector

    Appendix 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. AOGND AOGND...

  • Page 104: Rear Signal Connector Signal Descriptions

    INTR* line to indicate whether the information on MOSI is being sent to a module or Slot 0. 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.

  • Page 105: Appendix Cscxibus Connector

    Appendix 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. Figure C-1 shows the pin assignments for the SCXI-1121 SCXIbus connector. © National Instruments Corporation SCXI-1121 User Manual...

  • Page 106: Figure C-1. Scxibus Connector Pin Assignment

    GUARD GUARD GUARD GUARD GUARD CHSGND CHSGND CHSGND CHSGND CHSGND RSVD RESET* INTR* D*/A MISO CHSGND CHSGND CHSGND CHSGND +5 V +5 V MOSI SPICLK TRIG0 SCANCON Figure C-1. SCXIbus Connector Pin Assignment SCXI-1121 User Manual © National Instruments Corporation...

  • Page 107: Scxibus Connector Signal Descriptions

    Serial Peripheral Interface (SPI) Clock – Clocks the serial data on the MOSI and MISO lines. Open collector. I/O. MOSI Master-Out Slave-In – Transmits data from the SCXIbus to the module. Open collector. I/O. © National Instruments Corporation SCXI-1121 User Manual...
  • Page 108 Signal Name Description (continued) 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. Slot Select – When low, enables module communications over the SCXIbus. Totem pole.

  • Page 109: Scxi-1121 Front Connector

    Appendix 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. Figure D-1 shows the pin assignments for the SCXI-1121 front connector. Signal Column Signal Number Name...

  • Page 110: Front Connector Signal Descriptions

    SCXI-1121 Front Connector Appendix D Front Connector Signal Descriptions Signal Name Description CGND Chassis Ground – This pin is tied to the SCXI chassis. DTEMP Direct Temperature Sensor – This pin connects the temperature sensor to the MCH4+ when the terminal block is configured for direct temperature connection.
  • Page 111 Appendix D SCXI-1121 Front Connector Signal Name Description (continued) EX2+ Positive Excitation Output 2 – This pin is connected to the excitation channel 2 positive output. EX2- Negative Excitation Output 2 – This pin is connected to the excitation channel 2 negative output.
  • Page 112 Appendix 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. Figure D-1 shows the pin assignments for the SCXI-1121 front connector. Signal Column Signal Number Name...
  • Page 113 SCXI-1121 Front Connector Appendix D Front Connector Signal Descriptions Signal Name Description CGND Chassis Ground – This pin is tied to the SCXI chassis. DTEMP Direct Temperature Sensor – This pin connects the temperature sensor to the MCH4+ when the terminal block is configured for direct temperature connection.
  • Page 114 Appendix D SCXI-1121 Front Connector Signal Name Description (continued) EX2+ Positive Excitation Output 2 – This pin is connected to the excitation channel 2 positive output. EX2- Negative Excitation Output 2 – This pin is connected to the excitation channel 2 negative output.

  • Page 115: Appendix Escxi-1121 Cabling

    Appendix 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 •...

  • Page 116: Scxi-1340 Installation

    SCXI-1121 Cabling Appendix E 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 SCXI-1121 Rear MIO-16 Equivalent Signal Connector AOGND AIGND MCH 0+ ACH0 MCH 0- ACH8 MCH 1+ ACH1...

  • Page 117: Scxi-1341 Lab-Nb, Lab-Pc, Or Lab-Pc+ And Scxi-1344 Lab-Lc Cable Assembly

    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.

  • Page 118: Scxi-1341 And Scxi-1344 Installation

    +5 V 34-35 No Connect 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.

  • Page 119: Scxi-1342 Pc-Lpm-16 Cable Assembly

    No Connect DOUT4 SERDATIN DOUT5 DAQD*/A DOUT6 SLOT0SEL* DOUT7 SERCLK OUT2 No Connect +5 V 34-35 No Connect All other pins of the PC-LPM-16 pinout are not sent to the SCXI-1121 rear signal connector. © National Instruments Corporation SCXI-1121 User Manual...

  • Page 120: Scxi-1342 Installation

    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. SCXI-1121 User Manual © National Instruments Corporation...

  • Page 121: 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. © National Instruments Corporation SCXI-1121 User Manual...

  • Page 122: Scxi-1302 50-Pin Terminal Block

    5. Tighten the large strain-relief screws to secure the wires. 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. SCXI-1121 User Manual © National Instruments Corporation...

  • Page 123: Scxi-1302 Installation

    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. © National Instruments Corporation SCXI-1121 User Manual...

  • Page 124: Scxi-1351 Installation

    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. SCXI-1121 User Manual E-10 © National Instruments Corporation...

  • Page 125: Scxi-1343 Rear Screw Terminal Adapter

    N multichassis adapters. 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.

  • Page 126: Table E-4. Scxi-1343 Pin Connections

    Solder pad RSVD Solder pad No Connect Solder pad No Connect Solder pad No Connect Solder pad No Connect Solder pad No Connect Solder pad No Connect Solder pad No Connect Solder pad SCXI-1121 User Manual E-12 © National Instruments Corporation...

  • Page 127: 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.

  • Page 128: Figure F-2. Revision A And B Scxi-1121 General Parts Locator Diagram

    Revision A and B Photo and Parts Locator Diagrams Appendix F Figure F-2. Revision A and B SCXI-1121 General Parts Locator Diagram SCXI-1121 User Manual © National Instruments Corporation...

  • Page 129: Figure F-3. Revision A And B Scxi-1121 Detailed Parts Locator Diagram

    Appendix F Revision A and B Photo and Parts Locator Diagrams Figure F-3. Revision A and B SCXI-1121 Detailed Parts Locator Diagram © National Instruments Corporation SCXI-1121 User Manual...

  • Page 130: Customer Communication

    Filling out a copy of the Technical Support Form before contacting National Instruments helps us help you better and faster. National Instruments provides comprehensive technical assistance around the world. In the U.S. and Canada, applications engineers are available Monday through Friday from 8:00 a.m. to 6:00 p.m.
  • Page 131 National Instruments for technical support helps our applications engineers answer your questions more efficiently. If you are using any National Instruments hardware or software products related to this problem, include the configuration forms from their user manuals. Include additional pages if necessary.
  • Page 132 Completing this form accurately before contacting National Instruments for technical support helps our applications engineers answer your questions more efficiently.
  • Page 133 Documentation Comment Form ___________________________________________________ National Instruments encourages you to comment on the documentation supplied with our products. This information helps us provide quality products to meet your needs. Title: SCXI-1121 User Manual Edition Date: August 1994 Part Number: 320426B-01 Please comment on the completeness, clarity, and organization of the manual.

  • Page 134: Glossary

    American Wire Gauge bandwidth Celsius CH#+ Positive Input Channel Number signal CH#- Negative Input Channel Number signal CHAN Channel Select bit Chassis bit CHSGND Chassis Ground signal cold-junction reference CLKEN Clock Enable bit © National Instruments Corporation Glossary-1 SCXI-1121 User Manual...
  • Page 135 Forced Output Enable bit Forced Retransmit bit GBWP gain bandwidth product GUARD Guard signal hexadecimal HSCR Hardscan Control Register HSRS* Hardscan Reset bit hertz input current leakage inches INTR* Interrupt signal input/output SCXI-1121 User Manual Glossary-2 © National Instruments Corporation...
  • Page 136 Read bit RESET* Reset signal root mean square referenced single-ended (input) RSVD Reserved bit/signal resistance temperature detector RTEMP Read Temperature bit Referred To Input Referred To Output RTSI Real Time System Integration © National Instruments Corporation Glossary-3 SCXI-1121 User Manual...
  • Page 137 Underwriters Laboratory volts Positive Analog Supply signal Negative Analog Supply signal volts direct current volts input high volts input low volts output high volts output low Vrms volts, root mean square watts SCXI-1121 User Manual Glossary-4 © National Instruments Corporation...

  • Page 138: Index

    E-8 theory of operation, 3-8 to 3-10 SCXI-1340 warning against exceeding input cable assembly, E-1 to E-2 range, 2-19 installation, E-2 to E-3 analog input specifications, A-1 to A-2 SCXI-1341 © National Instruments Corporation Index-1 SCXI-1121 User Manual...
  • Page 139 SPI bus, 2-37 to 2-40 SCXI-1328 high-accuracy isothermal Configuration Register write timing terminal block, 2-21, 2-26 to 2-28, diagram, 2-40 2-30, 2-32 Module ID Register timing installation, 2-32 diagram, 2-40 jumper configuration, 2-27 SCXI-1121 User Manual Index-2 © National Instruments Corporation...
  • Page 140 See single-channel connection, 2-17 measurements. warning against exceeding input documentation range, 2-19 conventions used in manual, xii excitation channels, 2-19 organization of manual, xi-xii pin assignments, 2-14, D-1 © National Instruments Corporation Index-3 SCXI-1121 User Manual...
  • Page 141 2-15 to 2-17, SCXI-1351 one-slot cable D-2 to D-3 extender, E-10 temperature sensor connection, 2-19 unpacking the SCXI-1121, 1-4 FRT bit, 4-7 internal half-bridge completion, 2-11 to 2-12 functional overview. See theory of INTR* line and signal operation.
  • Page 142 3-12 digital control circuitry, 3-8 ONCE bit, 4-7 read procedure, 2-40 operating environment specifications, A-4 timing diagram, 2-40 operation of SCXI-1121. See theory of module programming, 5-9 to 5-11 operation. channel scanning from other OUTREF signal modules, 5-9...
  • Page 143 4-5 scanning (direct), 5-9 Slot-Select Register, 4-6 single-module multiplexed RESET* signal, 3-4, C-3 scanning (indirect), 5-9 Revision A and B SCXI-1121 signal single-module parallel conditioning module scanning, 5-9 detailed parts locator diagram, F-3 scanning examples, 5-13 to 5-15 general parts locator diagram, F-2...
  • Page 144 1-2 temperature sensor, 2-26 support for MIO-16 boards, 1-1 warning on hazardous voltages, 2-21 unpacking, 1-4 SCXI-1330 connector-and-shell assembly, SCXI-1121 registers, 4-1 to 4-4 2-19 to 2-20 Configuration Register SCXI-1340 description of, 4-3 to 4-4 cable assembly, E-1 to E-2...
  • Page 145 2-35 with rear signal connector, 3-5 communication signals, 2-37 to 2-40 with SCXI-1121 and data acquisition digital I/O signal connections, boards, 2-36, 5-2 2-35 to 2-37 signal descriptions, 3-4 to 3-5, pin assignments, 2-33, B-1...
  • Page 146 3-9 slot-select timing diagram, 2-38 analog output circuitry, 3-14 to 3-15 writing the slot-select number, 2-38 block diagram of SCXI-1121, 3-1 SLOT0SEL* signal calibration, 3-11 to 3-13 communicating on SPI bus, 2-37 to 2-40 equipment requirements, 3-11...

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