Access sbRIO/cRIO Built-in Serial Port from FPGA

Updated Oct 18, 2019

Reported In


  • cRIO-9067
  • RS-232
  • cRIO-9063
  • sbRIO-9627
  • 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 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 C-Series RIO Mezzanie Card.