COM Port

[Guest]

The PC has one Serial Port, a Modem is used (using COM1) we need to add a
device to the Serial port and and a different COM port than the Modem uses so
we try to set up COM3 but XP Pro is never happy with it. The COM3 ALWAYS has
a Yellow ! on it.
How do we get COM3 to work in this PC?

 

[Joe Grover]

You need to either assign COM3 different hardware addresses, or not use
COM1. By default COM1 and COM3 use the same resources, as do COM2 and COM4.