I've seen RS232 used for multiple devices before, but I'm sure 192 devices would be too many. I'll second @RobR, RS485 is probably your best bet.
@the1laz started
Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
I've seen RS232 used for multiple devices before, but I'm sure 192 devices would be too many. I'll second @RobR, RS485 is probably your best bet.