View232

View232 is a serial port (RS-232) monitor and logger that was available commercially from Blaise Computing Inc. in the late 1980's-early 1990's. It was written in Pascal and shipped with the source code (run V232SRC.exe). It runs on MS-DOS. These days it can be run in the free DOSBox (https://www.dosbox.com).
I found a great way to make a low cost, portable, serial monitor and logger, is to install DOSBox and View232 on a Raspberry Pi 400 (RPi 400, or RPi 500), then add 2x USB to Serial adapters. You can make the monitor cable from the diagram below. Help can be found in the program itself, by pressing F1.

View232 hasn't been available for many years and is very hard to find anywhere.  If you're looking for it.. look no further, as I found it in my archives from back in those days. Ask and you may get lucky.

Below is an advertisement from Byte Magazine February 1990, and the schematic for the all-important Data Monitor Cable...

Comms Automation and Protocol Simulation

Back in the mid 1980's I worked for an embedded systems manufacturer, and we had a need to simulate certain serial protocols. We did this using a Hewlett Packard 4952C Protocol Analyser. A newer version of this was the HP 4957A which had the RS232 comms "pod" built in. These devices could monitor and record serial comms. They could also run scripts we created, to initiate comms or respond in programmed ways to received serial communications, thus simulating a protocol.
These days you can do this with Docklight (commercial), or SerialTool (commercial, and not to be confused with SerialTools which has a protocol analyser but no automation/simulation) which includes a Python scripting API for automation. For free you could use Python with the pySerial library to create serial comms automation.