Using Both the RS-485 and RS-422 Protocols Simultaneously

Updated Nov 9, 2020



  • PXIe-8431/16
  • PCIe-8431/16

I have a PCI/PXI serial card. For some of the ports, I would like to use the RS-485 protocol. For the others, I would like to use the RS-422 protocol. Can I do this?

You are able to use both the RS-485 and the RS-422 protocols simultaneously with the same PCI/PXI, as long as that card supports the RS-485 protocol. All of the National Instruments RS-485 PCI and PXI cards also support RS-422. This includes the 8431 and 8433 series cards. 

Additional Information

The RS-485 protocol is a superset of the RS-422 protocol. In other words, the RS-485 protocol was built on the standards of the RS-422 protocol. Therefore, using the RS-485 protocol also makes use of the RS-422 protocol. You will always be able to use the RS-422 protocol within the RS-485 protocol.