Library function error/ cannot open port

[Anaël]

Hello,

I need help about a fatal error on labwindows :

Library function error / cannot open port

Yesterday, the code worked and today when I tried to run the code it didn't work. I don't know why.

The only thing I do it's to turn off the computer, update the computer, and connect again. However the code is the same that yesterday.

Thank you,

Anaël.

[RobertoBozzolo]

The error is quite clear: you are trying to access a device which does not exist in the system.

Which port are you trying to open? Is it a usb-to-serial device or some other removable one? Could it be that the associated virtual port has changed after the OS update?

Check in device manager whether a port with the number you are using actually exists in the system. If it has changed number, you can edit the device and return it to the original one, or you can change your program to use the new port number.

[Anaël]

Thank you Roberto,

Where can I check if the port is the same ? Because I think it's the same port .

Anaël.

[RobertoBozzolo]

Open Control Panel >> System, choose Device Manager  among the options on the left and open Ports branch in the devices tree: there you'll see which ports are present in the system and details for each one.

EDIT: actual names in OS screens could be slightly different: I am translating them by memory since I have no PC localized in English at the moment.

[Anaël]

Thank you it was something whose run in the same time I didn't see.

[RobertoBozzolo]

You're right, I was wrong: in case the port does not exist the library should return a "No port found" error. "Cannot open port" is returned if the port is already allocated to another process.