Using NI-9871 COM Ports When in Hybrid Scan Interface Mode

Updated May 3, 2018

Reported In


  • NI-9871
  • CompactRIO Chassis


  • LabVIEW
  • LabVIEW FPGA Module

Issue Details

Trying to use cRIO in Hybrid mode, but can't see the COM resources for the 9871 in LabVIEW.


If you are using LabVIEW 2017, you will need to compile and deploy an FPGA VI before you will be able to see the COM ports for the NI-9871. If this doesn't work, or you are using an earlier version of LabVIEW, proceed to the next steps.

In order to see the COM resources for the NI-9871 when using it in the Scan Interface and your cRIO is in Hybrid mode, you will need to do one of two things:
  1. Run the FPGA VI manually by clicking the Run button. Once the FPGA VI is running, you will be able to see the COM ports in MAX and in your Real-Time VI.
  2. Add at least a two second delay between programmatically opening the FPGA Reference and trying to access your VISA resources. Also note, that you will want to reference your FPGA VI by the compiled bitfile instead of pointing to the VI itself in the Open FPGA Reference VI.