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

Updated Nov 13, 2020

Reported In


  • NI-9871
  • NI-9870


  • LabVIEW Real-Time Module
  • LabVIEW FPGA Module



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. Why is that?


This is an enumeration error, caused by either incompatible NI-VISA versions, missing external power to the device, or software corruption.

To have the modules appear in the following configuration, follow the steps below.  

If you can see the COM ports, but not the module, skip to Step 2.

  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. Next, make sure that the NI 987x series modules are externally powered.
    • If the external power is not connected the COM ports will show under the Devices & Interfaces of your target, but not under the module tab.
  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.

Additional Information

You should also consider to upgrade, or downgrade the firmware of your CompactRIO regarding the version of NI-VISA driver you have installed on your device.