Access sbRIO/cRIO Built-in Serial Port from FPGA

Updated Dec 19, 2023

Reported In


  • cRIO-9067
  • RS-232
  • cRIO-9063
  • RS-485


  • LabVIEW FPGA Module
  • LabVIEW Real-Time Module


  • NI CompactRIO

Issue Details

  • My Single-Board RIO/CompactRIO has a built-in RS-232/RS-485 port, which I would like to access from FPGA, however, it does not show as an available resource in Project Explorer. Is it possible to access it through FPGA?
  • I have an RS-232/RS-485 device that I need to send a command and receive data from. I have this working on the scan mode, can I use the external serial port to communicate with the FPGA?


Built-in Serial ports of cRIO or sbRIO cannot be directly accessed through FPGA. These ports are accessible only from the Real-Time section, where they show up as a standard VISA resource. It is recommended to use Serial VIs and functions to communicate with devices connected to those ports. Additional functions are also available in the VISA palette.

If your application requires serial communication to be implemented on FPGA, there are several ways to do it, however, additional hardware may be necessary:

Please note, that it may not be possible to connect C-Series modules to all sbRIOs. In case your sbRIO does not have C-Series module connectors, but it is equipped with RMC Connector, you may still connect C-Series modules via CompactRIO Single-Board Controllers.