Closing a COM port with command prompt

Question

I need to be able to close COM ports through the command prompt (Windows 7 OS). The reason for this is that I work with a lot of experimental equipment, controlled with a language called LabVIEW, and communication to these devices is sometimes lost. Right now the only fix is to either rename the COM in device manager, or reboot. Ideally I'd like to close the port in command prompt, which I can implement programatically in my control software.

Does anyone know either; how to close a COM port in command prompt, or a quick and easy way of closing a COM port, so then I can reestablish a connection with my device?

Cheers!

Answer 1

I don't think you can simply close a resource that is in use by another program, this will undoubtedly lead to errors. Programmed correctly LabVIEW should not leave ports open, even if port are left open simply closing labview should be enough.

In LabVIEW programatically open and close the COM port, don't rely on the auto-closing of the VISA system. Also add timeouts to the serial connections, than you should get a connection error time out and be able to clean up the resource.

Basically you need to solve your problem at the origin, if help needed post your LabVIEW code.

Presuming you read from the serial port in a while loop, simply stop the while loop when an error is found, see the code snippet. This stops the loop and the resource will be closed outside the loop regardless of the error.