The Sensor Test sequence demonstrates temperature measurements captured with a thermistor, RTD, and thermocouple sensing devices using C Series temperature input modules (NI-9211, NI-9217), C Series voltage input modules (NI-9215), and analog input modules (TS-15100, TS-15200).

This TestStand sequence uses the LabVIEW measurement libraries. By default, the test sequence is installed to the following location: C:\Users\Public\Documents\National Instruments\PCB Assembly Test Toolkit for LabVIEW\TestStand\Automation\Sensor Tests

Required Driver Application Software

This sequence requires a supported version of NI-DAQmx.

Highlighted Features

  • Thermistor Test - cDAQ—Uses an analog input module with voltage excitation supplied by an analog output module in a cDAQ chassis to capture temperature. This example uses the following libraries:
    • DAQ_DC Voltage Generation
    • DAQ_Temperature Thermistor Measurement
  • Thermistor Test - TestScale—Uses an analog input module with voltage excitation supplied by a power supply module in a TestScale chassis to capture temperature. This example uses the following libraries:
    • DAQ_Power Supply Source and Measure
    • DAQ_Temperature Thermistor Measurement
  • RTD Test—Captures temperature on analog input modules. This example uses the Temperature RTD Measurement library.
  • Thermocouple Test—Captures temperature on analog input modules. This example uses the Temperature Thermocouple Measurement library.
  • Turn Off all AO Channels—Powers down all analog output channels by configuring an output voltage of 0 V. This example uses the DAQ_DC Voltage Generation library.
  • Power down all Power Supplies—Powers down all power supplies by disabling the output. This example uses the DAQ_DC Voltage Generation library.

    • Hardware Configuration

    The following figure illustrates the hardware connections for this example sequence.

    Figure 10. cDAQ Hardware Setup


    For cDAQ thermistor measurements, the analog input terminal configuration is differential and floating. To avoid common mode voltage errors, connect a direct wire or bias resistor between AIx- to COM based on the ground differences between the sensing and the measurement device. The possible bias resistor values range from 1 kΩ to 10 kΩ. Refer to Measurement System Types and Signal Sources for more information.

    Figure 11. TestScale Hardware Setup


    For the TestScale thermistor measurement, the default analog input terminal configuration is RSE.

    Refer to the documentation for your specific device for pinouts and other information necessary to adapt this example sequence to your application.

    For shielded thermocouple measurements, connect the COM terminal of your device to the shield. Connect the shield to a common-mode voltage reference for the thermocouple. A common-mode voltage reference is a voltage that is within ±1.2 V of the common-mode voltage of the thermocouple. If you are using a floating thermocouple or a thermocouple within ±1.2 V of earth ground, connect COM and the shield to earth ground. The shield grounding methodology varies depending on the application. Refer to the following for an illustration of a typical shielding configuration.



    Refer to Taking a Thermocouple Measurement in LabVIEW for details about thermocouple measurements using NI DAQ devices.

    Using the Sequence with Physical Hardware

    1. Run the sequence once in simulation mode. Running the sequence in simulation mode creates the required global virtual channels in NI MAX that you must modify.
      Note In this example, physical and global virtual channels are used to configure the terminal or pin to perform the instrument actions. Global virtual channels are software entities that encapsulate the physical channel along with other channel specific information such as range, terminal configuration, and custom scaling. You can create global channels in NI MAX and call them from measurement libraries.
    2. Right click the Import Hardware Config step and select Run Mode » Skip to skip the step.
    3. Configure the remaining sequences. Open each sequence and examine the Note to run with Hardware entry.
    4. Configure the Thermistor Test - cDAQ sequence.
      1. Open NI-MAX and update the physical channel linked to the global virtual channels used in the DC Voltage Generation and Temperature Thermistor Measurement initialize steps: TS_THEX and TP_TH0. Refer to Creating and Modifying Global Virtual Channels for more information.
      2. Update the Thermistor Parameter and Terminal Configuration based on your thermistor settings to ensure accurate temperature measurements.
      3. Review the analog output and analog input pin configurations for your use case.
      4. Save the sequence.
    5. Configure the Thermistor Test - TestScale sequence.
      1. Open NI-MAX and update the physical channel linked to the global virtual channels used in the Temperature Thermistor Measurement initialize step: TS_TH1. Refer to Creating and Modifying Global Virtual Channels for more information.
      2. Open the PS – Initialize step and update the Physical Channels input to use the TestScale power module pin.
      3. Update the Thermistor Parameter and Terminal Configuration based on your thermistor settings to ensure accurate temperature measurements.
      4. Review the analog output and analog input pin configurations for your use case.
      5. Save the sequence.
    6. Configure the RTD Test sequence.
      1. Open NI-MAX and update the physical channel linked to the global virtual channels used in the Temperature RTD Measurement initialize step: TP_RTD. Refer to Creating and Modifying Global Virtual Channels for more information.
      2. Update the RTD Type, Sensor Resistance at 0 deg C (ohm), Resistance Configuration, Current Excitation Source, Current Excitation (A), and ADC Timing Mode parameters based on your RTD settings to ensure accurate temperature measurements.
      3. Save the sequence.
    7. Configure the Thermocouple Test sequence.
      1. Open NI-MAX and update the physical channel linked to the global virtual channels used in the Temperature Thermocouple Measurement initialize step: TP_TC. Refer to Creating and Modifying Global Virtual Channels for more information.
      2. Update the Thermocouple Type, CJC Temp (deg C), Enable Autozero, and Auto Zero Mode parameters based on your RTD settings to ensure accurate temperature measurements.
      3. Save the sequence.
    8. Configure the Turn Off all AO Channels sequence.
      1. Open the DC Voltage Generation - Initialize AO Channels step and update the Physical Channels input to use your analog output channel.
      2. Review the analog output pin configurations for your use case.
      3. Save the sequence.
    9. Configure the Turn Off Power Channel sequence.
      1. Open the Initialize step and update the Physical Channels input to use your power channel.
      2. Review the analog output configurations for your use case.
      3. Save the sequence.