Serial COM Ports Missing in MAX or LabVIEW

Updated Dec 22, 2023

Reported In


  • Measurement & Automation Explorer (MAX)
  • LabVIEW



Issue Details

  • When I expand Devices and Interfaces in Measurement and Automation Explorer (MAX), the COM port for my serial device (ex: USB-232) does not show up.
  • When I try to open a VISA resource in LabVIEW, I cannot select any serial ports as a VISA Resource Name. 



This issue is usually caused by an improper or no installation of the NI-VISA driver. Without NI-VISA, MAX is unable to access or create serial, GPIB-VXI, or TCIP/IP interfaces. Follow the steps below to resolve the issue.
  • Make sure you have the latest compatible version of the full NI-VISA driver installed. Installing the NI-VISA Run-Time Engine will not allow you to access or create serial interfaces in MAX.
  1. Determine compatible driver versions by cross-referencing the following: 
  1. Use MAX to identify the version of the driver currently installed
  2. Install the version of NI-VISA if it is not the latest compatible one. Be sure that you select NI-VISA Configuration Support under "Additional Items you may wish to install" during your installation, as omitting this software during your installation will prevent NI-MAX from detecting any of your resources.
  1. Restart the computer.
  • Try to add the serial interface manually in MAX.
  1. In MAX, right click on Devices and Interfaces under My System and select Create New...
  2. Select Port (Serial or Parallel) and click Next
  3. Select ASRL Number and Serial Binding. Click Next.
  4. (Optional) Define an Alias.
  5. Click Next and then Finish.