Have a legacy device with a DE-9 connector? Dust off that USB-to-serial cable, fire up Sscom 5.13.1, and start listening. You might be surprised what your hardware is trying to tell you.
Let’s run a practical test: Communicating with an Arduino Uno (which uses the CH340G chip). Sscom 5.13.1 English
Typical Contents of a 5.13.1 Release