With the help of a dedicated serial port scanner software, it’s possible to check whether a COM port is working. Designed for Windows, Serial Port Monitor provides a set of advanced features for serial port testing.
Here are just some of the app’s capabilities that will let you test your RS232 ports:
Starting a monitoring session;
Recording the incoming and outgoing serial data to a file;
Reproducing a monitoring session back to a serial port;
Comparing sessions.