[nascar38]

I need to change a COM port on my laptop. I'm trying to program a PLC and it will only transfer the program using COM1 or COM2. I don't have a serial port therfore I have to use a port replicator and it defaults to COM4. I can't tell what is using COM1 or COM2 to change one of them to COM4. I do know my modem is using COM3

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right click on my computer-> properties go to tab hardware -> device manager.
open ports (com & lpt)
doubble click on Communications port - it shuould say what port it is in brackets.
click on port settings tab -> advanced
on the bottom COM Port Number -now pick you'r poision.
good luck

[vally]

right click on my computer-> properties go to tab hardware -> device manager.
open ports (com & lpt)
doubble click on Communications port - it shuould say what port it is in brackets.
click on port settings tab -> advanced
on the bottom COM Port Number -now pick you'r poision.
good luck

[nascar38]

It doesn't show anything for any COM Port only when I plug in the port replicator then it shows COM4. I did try to change the port to COM1 or COM2 but they both say they are being used. That's what I meant by saying I can't tell what's using COM1 or COM2. Thanks for you input though Vally.

[Neil Jones]

COM3 and COM4 are virtual COM ports.
It may well be that the laptop does have COM ports that aren't accessible from the outside - have a poke in the BIOS.

[Tyger]

Neil Jones is right, you may need to enable the com ports in the BIOS, also you may have connections for them on the mainboard but need to install the connectors to go to the outside world. You can also get PCI cards that have serial ports on them as add ons.