NI 987x Module's COM Ports Are Missing From NI MAX

Updated Aug 2, 2023

Reported In


  • NI-9871
  • NI-9870


  • LabVIEW Real-Time Module
  • LabVIEW FPGA Module


  • NI CompactRIO

Issue Details

I have installed the required software to use a NI 987x module on my CompactRIO, but the COM ports are still missing in NI Measurement & Automation Explorer (NI MAX) or appearing under devices and interfaces rather than under the module specific tab.


Please refer to Real-Time Controllers and Real-Time Operating System Compatibility to find out what operating system your cRIO controller is running.

NI Linux RT target

For NI Linux RT target, the serial ports appear under Devices and Interfaces but not under the NI 987x module.

Phar Lap ETS or VxWorks target

For Pharlap ETS or VxWorks target, the serial ports appear under the NI 987x module.


Installing Software and Detecting Hardware

  1. Make sure that the installed version of NI-VISA is the same on both development system, using the Software tab under both the cRIO and My System
    • If the wrong version is installed on the development system, you can download NI-VISA from here.
    • If you need to change the version on the CompactRIO, follow this guide to install the correct version. 
  1. When the device is powered, the next step depends on how your module is configured in the project explorer.
    • Scan Mode - If you are using the device is in scan mode then you must deploy the module. In the Project Explorer, right-click on the C Series module, select Deploy.
    • Hybrid Mode - If you are using the device in hybrid mode, then you must compile your top-level FPGA VI. Once compiled, you must run the compiled bitfile. You can do this with interactive mode, or by opening the reference inside of an Real-Time VI. This FPGA VI can be simple, but a bitfile must be created that combines the scan mode functionality with your custom FPGA code.
    • FPGA Mode -If you are in FPGA mode, there is no way to see the ports in Measurement & Automation Explorer.
  2. Finally, if none of the previous steps worked, you can also try to reformat the CompactRIO disk and reinstall the software. You can try to upgrade, or downgrade the firmware of your CompactRIO regarding the version of NI-VISA driver you have installed on your device.