Capture traffic between two external devices, using a serial port

Question

Two devices, A and B, communicate with each other via a serial port. I want to log the data exchanged between them. My plan is to use a PC with two COM ports - one connected to device A and the other to device B. I will use data logging software to "patch" both COM ports together. So whenever data comes in on port 1, it goes out through port 2, and vice versa. This way, devices A and B can continue to communicate normally, while I capture and verify the data being transmitted.

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).

https://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.