Capture traffic between two external devices, using a serial port

Question

Two devices, a and b, talk to each other with a serial port. I want to log the data. So my plan is to have a PC with 2 com ports, one connected to a the other to b, and have data logging software "patch" both com ports together, so whenever data comes in on port #1, it goes out port #2, and vice-versa. That way devices a and b will continue to talk together and function, and I can capture the data to see that it's correct.

Most serial loggers I've found log the data on the port(s), but don't actually do the relay, or patching, to send data from port #1 to #2 and vice-versa. Therefore, you can't use them to log the data between 2 external devices.

Will your software do what I need?

Answer

You should make the following cable and use our Advanced Serial Data Logger or Advanced Serial Port Monitor (in the manual mode).

http://www.aggsoft.com/rs232-pinout-cable/serial-port-monitor-cable.htm

In most cases the half-duplex cable is required. Therefore you'll need one serial port on the computer.