The LED Test sequence demonstrates measuring differential voltage across the anode and the cathode of the LED. The sequence also demonstrates the validation of a PWM signal with an analog buffer. The sequence simulates analog input and analog output channels or modules.

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\LED Tests

Required Driver Application Software

This sequence requires a supported version of NI-DAQmx.

Highlighted Features

  • Validate DC Level—Uses an analog input module to measure and validate the differential voltage across the anode and the cathode of the LED. This example uses the DC-RMS Voltage Measurement library.
  • Send and Validate PWM (Analog Buffer)—Uses an analog output channel to send PWM commands to the LED circuit. The PWM response is measured simultaneously in the test point with an analog input channel using a trigger. This example uses the following libraries:
    • DAQ_Signal Voltage Generation
    • DAQ_Time Domain Measurement
  • 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.

    • Hardware Configuration

    The following figures illustrate the hardware connections for this example sequence.


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

    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 Validate DC Level Sequence sequence.
      1. Open NI-MAX and update the physical channel linked to the global virtual channels used in the DC-RMS Voltage Measurement initialize steps: TP_LED0. Refer to Creating and Modifying Global Virtual Channels for more information.
      2. Review the power and analog input pin configurations for your use case.
      3. Save the sequence.
    5. Configure the Send and Validate PWM(Analog Buffer) sequence.
      1. Open NI-MAX and update the physical channel linked to the global virtual channels used in the Signal Voltage Generation and Time Domain Measurement initialize steps: TS_PWM_LED0 and TP_PWM_LED0. Refer to Creating and Modifying Global Virtual Channels for more information.
      2. Open the Time Domain Measurement - Configure capture settings for LED Measure step and update the Digital Trigger Source.
      3. Set Periodic waveform to True to perform time domain analysis in the measured data in the Time Domain Measurement - Fetch capture settings for LED Measure step.
      4. Review the power and analog input pin configurations for your use case.
      5. Save the sequence.
    6. 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.