NI-Serial COM Ports are Detected out of Order on Windows 7
Primary Software Version: 3.5.1
Primary Software Fixed Version: N/A
Secondary Software: N/A
With NI Serial hardware on Windows 7, I notice that the COM ports are not enumerating in order. I would expect that the ports would be assigned COM numbers in the same order as the ports appear on the hardware. Port 1 on the hardware should have the lowest available COM number on the system and the COM ports should be assigned in port order.
Windows 7 parallelizes the COM port enumeration process causing the ports of newly installed hardware to be enumerated in a random order with our driver. After the first time the hardware is enumerated, the COM numbers are saved in the Windows registry. If the NI-Serial driver is not uninstalled or if the hardware is not placed in different slots, the hardware will continue to have the same COM numbers assigned between reboots.
Upgrading to a later version of NI-Serial, performing a repair of NI-Serial, or uninstalling and reinstalling NI-Serial will cause the ports to re-enumerate. When this happens on Windows 7, the result will be that the ports enumerate out of order.
NiPortConfig.exe is a utility that allows you to manually assign a contiguous range of COM numbers to a board. It is located in the NI-Serial Installation Directory, which is C:\Program Files\National Instruments\NI-Serial on 32-bit operating systems and C:\Program Files (x86)\National Instruments\NI-Serial on 64-bit operating systems. It is only included with the full version of the driver, it is not installed with the runtime.
To use the utility:
Developer Zone: National Instruments Product Compatibility for Microsoft Windows 7
Report Date: 09/28/2009
Last Updated: 08/18/2014
Document ID: 51RBTPG2