USB- Serial Port -recreates COM port everytime I connect the device.


I have device that has got USB- Serial Port created whenever I plug it in and I have got all the drivers installed but every time I connect a new device out of the box it detects it as a new device and asks me to re-install the drivers and it keeps creating dynamic COM ports every time I plug in.I need help with this as I have 50 of the these units to be programmed .Why is it not able to keep the COM port Thoughts? Thanks Archie

Hi Archie,

Thanks for posting here in our support forum, I’ll be happy to help. The assignment of COM numbers is a Windows function so getting around it will be related to settings in Windows. The first thing to check would be if Windows is able to assigning consistent COM numbers to a single cable when it is connected and reconnected to the same USB port.

If that’s not working please forward over your Amazon Order Id and the serial numbers of the USB to Serial cables you have to us at and we’ll do our best to get your issue resolved.


Plugable Technologies.

Thanks for the reply Jerome!Actually this was from a customer ,I would see if they get to try another cable and see if their issue is resolved.I’ll keep you posted.


Thanks for the update Archie!


Jerome ,the customer is running into the same issue also with another cable.I feel it has to do something with his COM ports configuration on his computer not being static and generating dynamic ports,their IT support was unable to fix it. For now I asked him to try on another Windows machine and see if he running into the same problem.

Any Ideas?


Hi Archie,

Tell me if I’m understanding the issue correctly…

There’s multiple Plugable USB to Serial cables and when they are connected and disconnected they get arbitrary COM ports every time, so the same cable won’t get the same COM assignment twice in a row.

Is that correct?

To isolate what’s happening it would be good to set a base line of expectations. Try having them use just one cable and then after a fresh reboot connect it and see what the COM port is. Then disconnect it and reconnect and see if it get the same assignment.

Next try connecting it into a different port. Does Windows still recognize that it’s the same cable?

I think the issue may have to do with Windows reserving COM ports that have previously been assigned and for some reason not recognizing that a particular cable was previously seen and assigned.

Once you define what the behavior is of one cable regarding same USB port, different USB port, try adding another cable and see if Windows behaves as expected.

I hope his helps!