Quick update for today.
I am now running on the RS232 interface. Its as per the wiki, a stock DE9 interface for RS232. I made up a pair of 3 wire cross over cables to go between the PC USB to RS232 DE9 and the Units DE9.
i.e.
Pin 2 to Pin 3
Pin 3 to Pin 2
Pin 5 to Pin 5
A new thing that I found, that i have not seen in the official wiki yet, is the “key” button press to rotate from RS485 - RS232 - RS422 - RS485 … is not saved, so any power cycle or unit soft restart will revert back to the saved interface.
As such, the “key” press is really just to get it to an interface where you can talk to it, then +++\r\n to get access to the AT Commands, then set and save the settings you want.
Its unclear what the defaults are (again) is seems this may have changed over time. For my units on V1.3 the default was RS485 9600 baud 8N1. I have seen the reference to RS232 115200 baud 8N1 (as per what @Taylor94043 found) in the wiki as well.
