USB to Serial COM Port Assignment
We sell a number of USB to Serial adapters that will allow you to connect a serial device to a USB port on your computer. Installing the drivers will set up a COM port in the device manager, and from then on your computer will think that it is using a serial communication port.
Generally Windows will automatically assign the USB to Serial port as the first unused COM port… but Windows can see many things as
Sometimes as you disconnect and reconnect the USB to Serial, it will set up a new COM port each time you reconnect the adapter. (We had a test machine that got as high as COM14). If this is happening you can simply reassign the COM port and Windows should remember the new port and continue to use it in the future.
Changing the COM port is simple, we have detailed instructions on our USB to Serial Support page.
July 18th, 2006 at 5:15 pm
“Changing the COM port is simple…”. No it isn’t - it is many clicks through to the level where you can make the change.
Every time I restart my laptop, the USB comes up on a different serial port than it did last time, EVEN THOUGH IT STILL SHOWS THE OTHER PORTS AS AVAILABLE.
How about a simple APP that is jsut a drop down list and sets the COM port for the USB to serial?
July 27th, 2006 at 10:05 am
Frank - that sounds like a great idea. We will forward your feedback to Prolific (the company that writes the software drivers for the USB to Serial).
February 17th, 2007 at 12:19 am
Don’t know where to start this topic…why not here?
I have an SW-1301 USB to serial cable. I have a weather station hooked up to my laptop with Windows XP Media Center edition. After brief communication with the unit and some data download, I get a blue screen with the error “IRQL_NOT_LESS_OR_EQUAL”.
I had first used the driver from the CD and then downloaded the driver again from your site for the SW-1301 to make sure I had an up-to-date install file.
Weather app can only use COM ports 1 - 4. I have tried it with COM1 and COM2, as COM3 and COM4 are busy.
What is causing this consistent error?
February 26th, 2007 at 10:50 am
Sorry for the delay. this is not a common issue with this part. I’ve done some research, and the IRQL error can be related to hardware, drivers, or some software applications. Our 1301 uses Microsoft certified drivers, so it shouln’t cause a blue screen, but it might be a combination of the two applications running together.
Microsoft has a list of possible solutions here, I might suggest trying the adapter on another comptuer (if available), or trying to use a different serial application, even HyperTerminal to see if you can narrow what exactly is causing the stop error. If the serial adapter is bad, we will replace it. You can contact our support department for more details or troubleshooting steps.
April 28th, 2007 at 10:15 am
I HAVE A MOTOROLA E1 ROKR. I CAN ONLY CONNECT IT TO COMPUTER VIA USB CABLE. BUT THE SOFTWARE I USE NEEDS SERIAL PORT. IS THERE ANY WAY THAT CAN ASSIGN SERIAL PORT NUMBER TO USB CABLE? THANX
May 1st, 2007 at 1:55 pm
When I have seen similar data cables for Cell phones, they have required a specialized cable with separate drivers (and probably a built-in USB to Serial) Unfortnately I don’t know of any way to use a standard USB cable.
June 22nd, 2007 at 11:26 pm
Your article says “..changing com port is simple…we have detailed instructions in USB SERIAL SUPPORT PAGE…”. I eagerly clicked on it to read…and alas! it’s no longer available on the server. Can you please ‘reinstall’ the article for the benefit of people like me? Thanks
June 26th, 2007 at 1:44 pm
Sorry for the confusion, When we updated the sight, some of the static links changed. The link has been updated. Please let us know if you have any other questions.