Implementing RS-232, RS-422, or RS-485 with NI FPGA Hardware

Updated Sep 11, 2023

Reported In


  • RS-422/RS-485

Issue Details

I would like to implement RS-232, RS-422, or RS-485 serial protocol with an NI FPGA card. Is this possible and what are the considerations when attempting to implement these protocols?


Yes, you can implement RS-232, RS-422, and RS-485 protocols on NI FPGA cards. The main consideration is how to deal with the voltage levels of the signal when implementing RS-422 or RS-485. The DIO lines on most CompactRIO modules and R Series devices are single-ended 3.3V TTL, while RS-422 and RS-485 are differential voltage signals. To have a true RS-422/RS-485 interface you will need to add a signal translator between the FPGA card and your RS-422/RS-485 device(s).

An example implementation of the RS-232 Interface using LabVIEW FPGA can be found at the link in the Related Links section at the bottom of this page.