Setting up Output Voltage for NI FlexRIO FPGA Modules With NI 5741/2 Adapter Module

Updated Jan 17, 2024

Environment

Hardware

  • NI-5741
  • NI-5742
  • PXI FPGA Module for FlexRIO

NI-5741 and NI-5742 are two FlexRIO Signal Generator Adapter Modules for NI FlexRIO FPGA Module. Both of them have a maximum update rate of 1 MS/s and 16 bits resolution. The voltage range is -2.5V to 2.5V or 0V to 5V and it can be set to Bipolar or Unipolar. Bipolar set the voltage range from positive 2.5V to negative 2.5V, and Unipolar is from 0 to 5V. In this article, we will introduce the method of setting the Polarity Configuration programmatically to change the voltage range. 

Firstly, ensure that both the NI FlexRIO Driver and NI FlexRIO Adapter Module Support for LabVIEW are installed. We can configure the polarity by inserting FPGA IO node.

1.  Create FPGA I/O items in the Project Explorer window.

2. Click the FPGA I/O item in the Project Explorer window and drag it onto the block diagram to create a new FPGA I/O Node that is configured for that FPGA I/O item.

3. You can specify one polarity per 8 channels. Click the element section of the FPGA I/O Node to add a new FPGA I/O item. Select IO Module\Ch 7-0 Bipolar Enable from the drop-down menu. Connecting a False into the input terminal of IO Module\Ch 7-0 Bipolar Enable node will set the polarity of channel 0 to 7 as unipolar, which now the voltage range will 0V to 5V.

4. Expand the FPGA I/O Node to add additional FPGA I/O items for the remaining 8 channels. Click the element section of the FPGA I/O Node and select IO Module\Ch 15-8 Bipolar Enable from the drop-down menu.  Connecting a False into the input terminal of IO Module\Ch 15-8 Bipolar Enable node will set the polarity of channels 8 to 15 as unipolar, which now the voltage range of these channels become 0V to 5V.

polarity.png

Next Steps

As a getting-started guide, the shipping example can be utilized. For example, if NI 5742 is used, NI 5742 - Getting Started Multi Channel.lvproj located at C:\Program Files (x86)\National Instruments\LabVIEW 202x\examples\FlexRIO\IO Modules\NI 5742\NI 5742 - Getting Started Multi Channel is the shipping example that can be referred to.