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. So far i have had very little luck trying standard CRC used by protocols like x3.28. SAMPLE CAPTURES This repo includes some captures including one of a repeat volume message to help figure out the CRC algorythm used.