sbRIO Voltage Levels for RS-232/RS-485/RS-422 Ports

Updated Jan 25, 2023

Reported In


  • sbRIO-9626
  • sbRIO-9627

Issue Details

Which are the logic levels that the on board sbRIO RS-232/RS-485/RS-422 ports?


Output Logic States



High Logic

+5.5 Volts

TX+ set to +5 Volts

TX- set to 0 Volts

Low Logic

-5.5 Volts

TX+ set to 0 Volts

TX- set to +5 Volts

Additional Information

The RS-232 and RS-485 ports on the sbRIO are meant to be connected to other RS-232-compliant and RS-485-compliant devices. There is no need for external level translations or transceivers as they are already built in.

Image: sbRIO-9626 Console out RS-232 signal when booting up in safe mode