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National Instruments AMUX-64T User Manual

National Instruments AMUX-64T User Manual

Analog multiplexer with temperature sensor
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AMUX-64T
User Manual
Analog Multiplexer with Temperature Sensor
November 1994 Edition
Part Number 320253B-01
© Copyright 1989, 1994 National Instruments Corporation.
All Rights Reserved.

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Summary of Contents for National Instruments AMUX-64T

  • Page 1 AMUX-64T User Manual Analog Multiplexer with Temperature Sensor November 1994 Edition Part Number 320253B-01 © Copyright 1989, 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,...

  • Page 3: Limited Warranty

    Limited Warranty The AMUX-64T 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

    Power-On Sequence.......................2-11 Chapter 3 Signal Connections ......................3-1 I/O Connector.........................3-2 Differential Connections....................3-4 Using the AMUX-64T for Thermocouple Measurements..........3-4 Selecting the Gain and Input Ranges ..............3-4 Linearizing the Data...................3-5 Differential Measurements.................3-6 An Example of Using Thermocouples (Differential) ........3-7 Procedure 1 ....................3-7 Procedure 2 ....................3-8...
  • Page 6 Theory of Operation and Register-Level Programming ........5-1 Functional Overview......................5-1 How to Address AMUX-64T Analog Input Channels...........5-3 A/D Conversions on a Single AMUX-64T Analog Input Channel ....5-3 Automatic Channel Scanning with the AMUX-64T............5-6 Scanning Order ......................5-9 Programming Channel Scanning with the AMUX-64T ..........5-10 Initialize the AMUX-64T Scanning Counter.............5-10...
  • Page 7 Table 3-4. Thermocouple Measurement Accuracies ..............3-10 Table 4-1. Component Positions in Each Channel ..............4-2 Table 5-1. AMUX-64T Channel Selection................5-4 Table 5-2. Multiple AMUX-64T Board Addressing ..............5-5 Table 5-3. AMUX-64T Scanning Order for Each MIO Board Input Channel......5-9 © National Instruments Corporation AMUX-64T User Manual...

  • Page 8: About This Manual

    National Instruments MIO board (except the AT-MIO-64). The AMUX-64T also has an integrated circuit temperature sensor that can be connected as a differential input to two of the 64 input channels (jumper-selectable) for low-cost thermocouple cold junction compensation.
  • Page 9 MIO board. • Appendix A, Specifications, lists the specifications for the AMUX-64T. • Appendix B, Customer Communication, contains forms you can use to request help from National Instruments or to comment on our products and manuals.

  • Page 10: Conventions Used In This Manual

    NB refers to the NuBus series computers. PC refers to the IBM PC/XT, the IBM PC AT, and compatible computers. Abbreviations, acronyms, metric prefixes, mnemonics, symbols, and terms are listed in the Glossary. © National Instruments Corporation AMUX-64T User Manual...

  • Page 11: Related Documentation

    About This Manual National Instruments Documentation The AMUX-64T User Manual is one piece of the documentation set for your system. You could have any of several types of manuals, depending on the hardware and software in your system. Use the different types of manuals you have as follows: •...
  • Page 12 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.

  • Page 13: Chapter 1 Introduction

    AT, MC, NB, NEC, and SB versions of that board. The AMUX-64T is a circuitboard assembly that is placed on a workbench or mounted in a 19-in. rack. You can configure the AMUX-64T to draw power from the MIO board or from an external +5 V supply.

  • Page 14: Software Programming Choices

    Introduction Chapter 1 Software Programming Choices There are four options to choose from when programming your National Instruments DAQ and SCXI hardware. You can use LabVIEW, LabWindows, NI-DAQ, or register-level programming software. Your accessory hardware kit does not include software. The AMUX-64T works with LabVIEW for Windows, LabVIEW for Macintosh, LabWindows for DOS, and LabWindows/CVI for Windows, NI-DAQ for PC compatibles, and NI-DAQ for Macintosh.
  • Page 15 NI-DAQ does not sacrifice the performance of National Instruments data acquisition devices because it lets multiple devices operate at their peak performance—up to 500 kS/s on ISA computers and up to 1 MS/s on EISA computers.

  • Page 16: Figure 1-1. The Relationship Between The Programming Environment

    Visual Basic, Turbo Pascal, Microsoft C with SDK, and Borland C++ for Windows and Microsoft Visual C++ for Windows NT. You can use your AMUX-64T, together with other PC, AT, MC, EISA, DAQCard, and DAQPad Series DAQ and SCXI hardware, with NI-DAQ software for PC compatibles.

  • Page 17: Register-Level Programming

    Introduction Register-Level Programming The final option for programming any National Instruments DAQ hardware is to write register- level software. Writing register-level programming software can be very time-consuming and inefficient, and is not recommended for most users. The only users who should consider writing register-level software should meet at least one of the following criteria: •...

  • Page 18: Unpacking

    National Instruments catalog or call the office nearest you. Unpacking Your AMUX-64T board is shipped in an antistatic package to prevent electrostatic damage to the board. Electrostatic discharge can damage several components on the board. To avoid such damage in handling the board, take the following precautions: •...

  • Page 19: Configuration And Installation

    AMUX-64T to the MIO board, power, and signal connections. Board Configuration The AMUX-64T contains two sets of switches and three jumpers to change the multiplexer settings and power connection configurations of the board. These jumpers and switches are shown in Figure 2-1.

  • Page 20: Figure 2-1. Amux-64T Parts Locator Diagram

    Configuration and Installation Chapter 2 Product Name and Assembly Number Serial Number Temperature Sensor Figure 2-1. AMUX-64T Parts Locator Diagram AMUX-64T User Manual © National Instruments Corporation...

  • Page 21: Table 2-1. Power Supply Selection

    Configuration and Installation Table 2-1. Power Supply Selection Switch Description Configuration INT position—Use this setting to configure the AMUX-64T to draw +5 V power through the MIO board. (factory setting) Internal Power Selected EXT position—Use this setting to draw +5 V power from an external supply connected to connector J41.

  • Page 22: Supplementary Configuration Information

    Supplementary Configuration Information Power Supply Selection Switch SW1 selects internal or external +5 V power for the AMUX-64T. Set SW1 to the INT position to power the AMUX-64T by drawing power through the MIO board. Set SW1 to the EXT position to draw power from an external +5 V source connected to J41.

  • Page 23: Temperature Sensor

    Use jumper W1 to select either the temperature sensor or the external screw terminals as the input source for differential channel 0. The AMUX-64T is shipped from the factory with the jumpers set so that CH0 and CH32 are connected to the terminal block (the temperature sensor is not selected).
  • Page 24 Ground the rack should via a ground strap or other recommended ways. You may ground it using jumper W3. In general, you will get the best results if all grounds and shields have exactly one conduction path to earth ground. AMUX-64T User Manual © National Instruments Corporation...

  • Page 25: Single-Board And Multiple-Board Configurations

    Configuration and Installation Single-Board and Multiple-Board Configurations The AMUX-64T is designed so that up to four AMUX-64T boards can be daisy-chained and connected to a single MIO board, as shown in Figure 2-2. You can configure the five-position switch labeled U12 according to the number of boards daisy-chained together. This switch is also used to assign distinct channel addresses to different AMUX-64T boards.

  • Page 26: Figure 2-2. Daisy-Chaining Multiple Amux-64T Boards

    Single-Ended Differential When you connect two or more AMUX-64T boards together, the multiplexers on different boards must be enabled at different times. Therefore, each board is assigned a different channel address range determined by the configuration of switch U12. The switch settings for each board configuration are given in the following sections.

  • Page 27: Single-Board Configuration

    Chapter 2 Configuration and Installation Single-Board Configuration The AMUX-64T is shipped from the factory with U12 set for single-board configuration as shown in Table 2-5. Two-Board Configuration For the two-board single-ended configuration, assign one board channel addresses from 0 to 63, and assign the other board channel addresses from 64 to 127.

  • Page 28: Installation

    AMUX-64T to J1 or J2 on another AMUX-64T, and so on (see Figure 2-2). You can install the AMUX-64T into a 19-in. rack-mount kit as shown in Figure 2-3. If you use a round 68-pin shielded cable, route the cable as shown, leaving passage for the ribbon cable (if you use it for daisy-chaining) in the other direction.

  • Page 29: Power-On Sequence

    Configuration and Installation Power-On Sequence If the AMUX-64T is powered by an external power source, you must turn on power to the AMUX-64T before turning on the computer. Similarly, you must turn off power to the AMUX-64T after turning off the computer. The red LED, labeled D2, indicates when power is applied to the board.

  • Page 30: Chapter 3 Signal Connections

    Chapter 3 Signal Connections This chapter describes the AMUX-64T signal connections and has specifications and connection instructions for the AMUX-64T connector signals. The following warnings contain important safety information concerning hazardous voltages. Warning: Connections that exceed any of the maximum ratings of input signals on the AMUX-64T board can damage the AMUX-64T, the MIO board, or the computer.

  • Page 31: Table 3-1. Pin Mapping For I/O Connectors J1, J2, And J42

    Pin Numbers 1, 2 24, 27, 29, 32, 56, 59, 64, 67 54, 55 24, 33 4, 7, 9, 12, 13, 15, 18, 35, 36, 39, 44, 50, 53 34, 35 8, 14 AMUX-64T User Manual © National Instruments Corporation...

  • Page 32: Figure 3-1. Amux-64T Signal Routing

    The signals from the AMUX-64T input connector screw terminals are connected to the MIO board via J1, J2, or J42 as shown in Figure 3-1. Observe that AISENSE is connected directly to the MIO board AISENSE pin and that AIGND on the AMUX-64T is connected to the AIGND signal of the MIO board.

  • Page 33: Differential Connections

    Chapter 3 Differential Connections On the AMUX-64T, channels 0 through 31 are connected to channels 0 through 7 of the MIO board. AMUX-64T channels 32 through 63 are connected to channels 8 through 15 of the MIO board. If the MIO board is configured for differential mode, the AMUX-64T input channels are automatically used in differential mode.

  • Page 34: Linearizing The Data

    Tables for the Letter-Designated Thermocouple Types Based on the ITS-90, National Institute of Standards and Technology, 1993. 2 All temperatures are the difference between the measuring end and the cold junction, or AMUX-64T screw terminals in this case. Linearizing the Data Thermocouple output voltages are highly nonlinear.

  • Page 35: Differential Measurements

    (for example, CH1 and CH33, CH2 and CH34, and so on). Notice that some thermocouples, such as those from Omega Engineering, have red insulation on the negative terminal. Check with the vendor to determine the output polarity of any particular AMUX-64T User Manual © National Instruments Corporation...

  • Page 36: An Example Of Using Thermocouples (Differential)

    A thermocouple table shows that the output voltage will never exceed 16 to 17 mV (recall that the exact voltage measured is a function of the AMUX-64T temperature as well as the temperature being measured). Therefore, you could select either a ±5 V input range with a gain of 100 (±50 mV maximum signal) or a ±10 V input range with a...

  • Page 37: Procedure 2

    1 or 10 (10 for the best resolution). Multiply the voltage by 100 to get the AMUX-64T temperature in degrees Celsius. For example, if the reading is 0.25 V, then the AMUX-64T is at 25° C.

  • Page 38: Single-Ended Measurement

    If you use two AMUX-64T boards, the sensors will appear at channel 0 for board A and channel 64 for board B. If you use four AMUX-64T boards, the sensors will appear at channel 0 for board A, channel 64 for board B, channel 128 for board C, and channel 192 for board D (see the Single-Board and Multiple-Board Configurations section earlier in this chapter).

  • Page 39: Thermocouple Measurement Accuracies

    MIO board so that you can ignore offsets. You can eliminate offset error, however, by grounding one channel on the AMUX-64T and measuring it. This value is the offset of the MIO board, and it can then be subtracted in software from all other readings.

  • Page 40: Signal Conditioning

    + SIGNAL - SIGNAL SCREW TERMINALS +5 V +5 V Jumpers Installed at Factory AIGND AIGND To Input ACH 33 ACH 1 Multiplexer (-in) (+in) on MIO board Figure 4-1. Onboard Equivalent Circuit © National Instruments Corporation AMUX-64T User Manual...

  • Page 41: Table 4-1. Component Positions In Each Channel

    R120 (28, 60) R177 R178 R179 R180 R121 R122 (29, 61) R181 R182 R183 R184 R123 R124 (30, 62) R185 R186 R187 R188 R125 R126 (31, 63) R189 R190 R191 R192 R127 R128 AMUX-64T User Manual © National Instruments Corporation...

  • Page 42: Application Notes

    The following applications require you to make modifications to the printed circuit board, usually in the form of removing jumpers and adding components. The AMUX-64T board is shipped with wire jumpers in the E and F positions (see Table 4-1 and Figure 4-1).

  • Page 43: Connecting Nonreferenced Or Floating Signal Sources

    You can install these bias resistors in positions B and D (Table 4-1 and Figure 4-1) of the AMUX-64T board. Figure 4-2 shows both the schematic and the component placement for a single 100-kΩ bias return resistor on the negative input from a floating source connected to channel 1 (the D position in Table 4-1).

  • Page 44: Single-Ended Inputs

    AISENSE, which connects to the negative input of the instrumentation amplifier on the MIO board. You can leave the inputs of the AMUX-64T board in the factory- default condition, that is, with jumpers in the series position (E or F, depending on the channel).

  • Page 45: Building Lowpass Filters

    Chapter 4 Building Lowpass Filters You can easily install simple resistance-capacitance (RC) lowpass filters in the AMUX-64T board on any differential input channel. The filters are useful for accurate measurement and noise rejection. By substituting resistance and capacitance values into the following formula...

  • Page 46: Building Highpass Filters

    1. If the input signal source is floating, you must place a bias return resistor in the D position (R8 in this case). Do not install RC lowpass filters on the AMUX-64T board open component locations when the MIO board is configured for single-ended inputs.

  • Page 47: Figure 4-5. Normalized Frequency Response Of Highpass Filter

    6.34 kΩ. Figure 4-6 shows both the schematic and the component placement for a 50-kHz highpass filter placed on differential input channel 1. If the input signal source is floating, you must place a bias return resistor in the D position (R8 in this case). AMUX-64T User Manual © National Instruments Corporation...

  • Page 48: Building Attenuators (Voltage Dividers)

    Capacitors have poorer tolerances than resistors, and matching of the input impedances is crucial for good common-mode rejection. Do not install RC highpass filters on the AMUX-64T board open component locations when the MIO board is configured for single-ended inputs. E R67...

  • Page 49: Figure 4-7. Attenuator For Use With Differential Inputs

    Therefore, the input to the MIO board (V MIO ) • G where V is the voltage applied to the screw terminals of the AMUX-64T. The accuracy of this gain equation depends on the tolerances of the resistors used. E R67 A R5...
  • Page 50 10 k Ω + 10 k Ω + 10 k Ω Therefore, When the MIO board is configured for ±10 V inputs, the board can acquire ±30 V signals with this attenuator circuit. © National Instruments Corporation 4-11 AMUX-64T User Manual...

  • Page 51: Theory Of Operation And Register-Level Programming

    Chapter 5 Theory of Operation and Register-Level Programming This chapter contains a functional overview of the AMUX-64T and explains the operation of each functional unit making up the AMUX-64T. This chapter also contains register-level programming information for the MIO board.

  • Page 52: Figure 5-1. Amux-64T Block Diagram

    (Optional) Figure 5-1. AMUX-64T Block Diagram The AMUX-64T multiplexers are controlled by a 4-bit scanning counter that is loaded via the 4-bit digital I/O port A of the MIO board. The MIO signal EXTSTROBE* loads the value at digital I/O port A into the AMUX-64T scanning counter. The MIO signal SCANCLK, which is active during scanned data acquisition, switches the input channels automatically on the AMUX-64T after each A/D conversion.

  • Page 53: How To Address Amux-64T Analog Input Channels

    A/D Conversions on a Single AMUX-64T Analog Input Channel Before an AMUX-64T channel can be selected, digital I/O port A must be enabled as a digital output port. You can enable this port by setting the DOUTEN0 bit in the MIO Command Register 2 (this bit has different names depending on your MIO board).

  • Page 54: Table 5-1. Amux-64T Channel Selection

    Bits ADO2 and ADO3 select each individual AMUX-64T board in a multiple-board configuration. If you use only one AMUX-64T board, ADO2 and ADO3 are ignored. If you use two AMUX-64T boards, only ADO2 is used. An address map for the different channel groups is shown in Table 5-2.

  • Page 55: Figure 5-3. Amux-64T Channel Address Mapping

    128–191 192–255 Observe that channels on a single AMUX-64T are labeled 0 through 63. If you use more than one AMUX-64T board, however, channel numbering changes (see Table 5-2). When you use four AMUX-64T boards with channel addresses ranging from 0 to 255, eight bits are required to address any single channel.

  • Page 56: Automatic Channel Scanning With The Amux-64T

    To perform an A/D conversion on a single AMUX-64T channel, perform the following programming steps: 1. Select an analog input channel on the AMUX-64T by writing the appropriate channel address bits to digital I/O port A (bits 0 through 3 of the Digital Output Register).

  • Page 57: Figure 5-4. Two-Level Multiplexer Arrangement Showing Channel 9 Selected

    A are scanned first, followed by the first four channels on board B. If four AMUX-64T boards are attached to the MIO board, then 16 AMUX-64T channels must be scanned for every MIO board input channel. For example, channels 0 through 3 on AMUX-64T...

  • Page 58: Figure 5-5. Scanning Order For Different Amux-64T Board Configurations

    CH3 (131) CH0 (192) CH1 (193) Board D CH2 (194) CH3 (195) Channel Number as Addressed from MIO Board Channel Number as Labeled on AMUX-64T Figure 5-5. Scanning Order for Different AMUX-64T Board Configurations AMUX-64T User Manual © National Instruments Corporation...

  • Page 59: Scanning Order

    188–191 252–255 For example, if one AMUX-64T board is used, channels 0 through 3 on the AMUX-64T are automatically scanned whenever channel 0 on the MIO board is selected in the scan sequence. If two AMUX-64T boards are used, channels 0 through 3 (board A) and channels 64 through 67 (board B) are automatically scanned.

  • Page 60: Programming Channel Scanning With The Amux-64T

    Chapter 5 If the MIO board is programmed with a sequential channel scan sequence (0 through 7 or 0 through 15) the AMUX-64T channels are scanned from top to bottom in the order given in Table 5-3. If only one AMUX-64T board is used, the channels are scanned in the order 0 through 63 for single-ended configuration.

  • Page 61: Set The Scan Div Bit In Mio Command Register 1

    Set the SCANDIV Bit in MIO Command Register 1 To enable SCANCLK division, set the SCANDIV bit in Command Register 1. After this programming sequence, the analog inputs on the AMUX-64T are automatically scanned during MIO-scanned A/D conversion operations. © National Instruments Corporation...

  • Page 62: Appendix A Specifications

    Appendix A Specifications This appendix lists the specifications of the AMUX-64T. These specifications are typical at 25° C unless otherwise noted. Analog Input Input Characteristics Number of channels Single board ............64 single-ended or 32 differential Two boards............128 single-ended or 64 differential Four boards connected ..........256 single-ended or 128 differential...
  • Page 63 Specifications Appendix A Four AMUX-64T Boards Gain AT-MIO-16E-2 AT-MIO-16E-10 NB-MIO-16 ±FS ±FS ±FS 0 to +FS 0 to +FS 0 to +FS — — — — — — — — — — — — — — Cold-Junction Sensor Jumper selectable on differential channel 0 Output ..............

  • Page 64: Appendix B 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 65 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 66 Completing this form accurately before contacting National Instruments for technical support helps our applications engineers answer your questions more efficiently.

  • Page 67: Austin, Tx

    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: AMUX-64T User Manual Edition Date: November 1994 Part Number: 320253B-01 Please comment on the completeness, clarity, and organization of the manual.

  • Page 68: Glossary

    DAC output update signal DACWRT DAC Write signal data acquisition DAQD*/A Data Acquisition Board Data/Address Line signal DAC0OUT, DAC1OUT Digital-to-Analog Converter 0, 1 Output signals DATA Data Lines at the Specified Port signal decibels © National Instruments Corporation Glossary-1 AMUX-64T User Manual...
  • Page 69 Serial Clock signal SERDATIN Serial Data In signal SERDATOUT Serial Data Out signal SLOT0SEL* Slot 0 Select signal SPICLK Serial Peripheral Interface Clock signal Slot-select signal Strobe Input signal transistor-transistor logic typical AMUX-64T User Manual Glossary-2 © National Instruments Corporation...
  • Page 70 Unipolar/bipolar bit volts V ± positive/negative input voltage common-mode noise differential input voltage diff volts direct current external voltage virtual instrument measured voltage Vrms volts, root-mean-square signal source watts WRT* Write signal © National Instruments Corporation Glossary-3 AMUX-64T User Manual...

  • Page 71: Index

    A-1 configuration. number of channels, A-1 4-board configuration. See four-board signal ranges, A-1 configuration. analog multiplexer. See AMUX-64T. AT-MIO-16. See MIO board. attenuators, 3-9 to 3-11 automatic channel scanning, 4-6 to 4-10 A/D, vi conversions on a single analog input...
  • Page 72 B-1 ground selection, 2-9 daisy-chaining mutliple AMUX-64T ground-referenced signal sources, boards, 2-4 connecting, 3-5 desoldering on the AMUX-64T, 3-3 differential inputs, 3-5 differential channel 1 single-ended inputs, 3-5 highpass filter, 3-9 lowpass filter, 3-7 differential connections, 2-12...
  • Page 73 1, 3-7 normalized frequency response, 3-6 LSB, vi onboard equivalent circuit, 3-1 operating environment specifications of AMUX-64T, A-2 operation and programming of AMUX-64T, 4-1 to 4-11 manual. See documentation. optional equipment, 1-5 MC-MIO-16. See MIO board. overvoltage protection, active, A-1 measurements, thermocouple.
  • Page 74 Index register-level programming, 1-4 single-ended connections for floating signal sources, 3-10 soldering on the AMUX-64T, 3-3 RTSI, vi specifications analog input, A-1 environment, A-2 physical, A-2 power requirements, A-2 settling times, A-1 to A-2 SCANDIV bit, 4-11 storage environment specifications of...
  • Page 75 Index VDC, vi voltage dividers. See attenuators. W1 jumper settings, 2-8 W2 jumper settings, 2-9 what you need to get started, 1-1 © National Instruments Corporation Index-5 AMUX-64T User Manual...

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