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Programming Digital I/O with LabVIEW

Last Modified: August 8, 2019

You can use LabVIEW Real-Time (RT) Express VIs, LabVIEW RT Low Level VIs, and LabVIEW FPGA I/O nodes to program the Digital Input/Output channels. In particular, the LabVIEW ELVIS III Toolkit provides Express VIs and Low Level VIs that you can use to generate various types of digital signals, including I2C, PWM, SPI, and UART.

Programming Examples

The LabVIEW ELVIS III Toolkit provides examples of using digital input and output channels to perform signal acquisition and generation. You can find these examples in the labview\examples\ELVIS III\Real-Time Control Applications\Digital IO\Digital IO.lvproj directory.

LabVIEW RT Express VIs

Use the Express VIs to interactively configure the settings for the I/O channels. When you place an Express VI on the block diagram or double-click an Express VI, a configuration dialog box appears. Use this configuration dialog box to configure the Express VI. Find the Express VIs on the Academic I/O»Control I/O subpalette on the Functions palette, as shown in the following figure:

The LabVIEW ELVIS III Toolkit provides the following Express VIs to access the Digital Input/Output channels:

LabVIEW RT Low Level VIs

Use the Low Level VIs to have more programmatic access to settings of I/O channels. For example, you can use the Low Level VIs to open or close certain channels and change the channel configuration at run time. Find the Low Level VIs on the Low Level palette, as shown in the following figure:

The LabVIEW ELVIS III Toolkit provides the following Low Level VIs to access the Digital Input/Output channels:

Select Help»Show Context Help or press <Ctrl-H> to display the Context Help window, from where you learn the basic information about each of the Express VIs and Low Level VIs. To learn more details about the VIs, refer to the LabVIEW ELVIS III Toolkit Help by clicking Detailed help at the bottom of the Context Help window, shown as follows:

LabVIEW FPGA I/O nodes

Use the FPGA I/O nodes from the FPGA palette to access the Digital Input/Output channels on the NI ELVIS III. You can also use the FPGA I/O property nodes if needed. Channels from both banks on the NI ELVIS III can be used in a single FPGA I/O node. The I/O banks are denoted as connectors in the software. The following figure shows a VI that uses FPGA I/O nodes to generate outputs to DIO channels 0 to 1 on Connector A and read inputs from DIO channels 0 to 1 on Connector B.

Refer to the FPGA I/O Functions section of the LabVIEW FPGA Module Help for detailed information about using the FPGA I/O nodes to perform operations on FPGA targets. Refer to the NI ELVIS III section in the NI Compact RIO Device Drivers Help to learn what terminals and I/O methods and properties you can access for the NI ELVIS III. You can access these help files by selecting Help»LabVIEW Help in LabVIEW, or search for their online versions on ni.com/manuals.


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