OrionM7100RS485
Effort to decode the M7100 RS485 head control protocol
PHY Layer
PHY layer is pretty straight forward its rs485, 38400baud, with what seems to be a seperate ctrl/priority line used to indicate if the bus is free.
Data Layer
Some simple data captures shows a pretty easy format.
Src 1001 Dst counter msg 1017 checksum 1016 dst
96 1001 E1 FC 0000 1B 5B48564F4C203D203238 1017 860F 1006 E1 96
This will display "VOL = 28" on the second line of the LCD.
Decoding the msg portion is very straight forward. The checksum is a different story.
CRC in this case is on 1001 E1 FC 0000 1B 5B48564F4C203D203238 1017 and uses CRC16 with the endianess flipped.
https://crccalc.com/ crc16/x-25 is the right one.. gives 0x0F86 which is you flipp is 860F... CRC solved!
Sample Captures
This repo includes some captures including one of a repeat volume message to help figure out the CRC algorythm used.