Yes, I have also looked at their "Modbus" and they definitely smoked something when they created that protocol. I have no idea why they wanted to invent the square wheel when there are round ones which work well... Modbus is open standard, and it was open ALL the time, so there was really no reason for them to create their own and invent something which is NOT Modbus.
Yes, there are some people who managed to decipher and implement plugins for both Mach3 and UCCNC so users can use RS485, but it is sooooooo much easier to implement in Brains in Mach3, or writing macros for UCCNC when the protocol is standard Modbus. It took me an hour in Mach3 to get the basic controls working and only a half an hour to write a basic macro code for UCCNC. Of course, today I have more than just ON/OFF/FWD/REV and RPM controls...