DC 12V Relay Module 16 Channel MODBUS RTU RS485 Relay Module Board PLC Controller Serial Port Switch

Board works good so far in testing, will give it a good workout in a harsh environment (no temp/humidity control) soon and that will be the real test.If you want to get started quick, I generated some command stringsfrom Various Sources including davedarko team on hackaday dot iovisit that team for additional commands .Strings for up to 8 relays ON/OFF below generated from application called Modbus Tools .Basically, the string is composed of :Unit ID (set by the dip switches, this assumes switch 1 only is up (ID=1))Mode (Write Register in this case)Register Location/Address ( from 0x0001 to 0x0010 for 16 relay board)Value to place in register (256 decimal = ON, 512= OFF, 768=Toggle,CRC (See MODBUS RTU SPEC as to how to calculate)Raw RTU in HEX per relay channel / state.COM CONNECTION AS TESTED:9600, N , 8, 1(Modbus Tools Defaults toEven parity which will sortofwork with errors , but no errorswith Parity set to None)FULL RTU WITH CRCUnit|mode|reg|value|crc01 06 00 01 01 00 D9 9A 1 ON01 06 00 02 01 00 29 9A 2 ON01 06 00 03 01 00 78 5A 3 ON01 06 00 04 01 00 C9 9B 4 ON01 06 00 05 01 00 98 5B 5 ON01 06 00 06 01 00 68 5B 6 ON01 06 00 07 01 00 39 9B 7 ON01 06 00 08 01 00 09 98 8 ON01 06 00 01 02 00 D9 6A 1 OFF01 06 00 02 02 00 29 6A 2 OFF01 06 00 03 02 00 78 AA 3 OFF01 06 00 04 02 00 C9 6B 4 OFF01 06 00 05 02 00 98 AB 5 OFF01 06 00 06 02 00 68 AB 6 OFF01 06 00 07 02 00 39 6B 7 OFF01 06 00 08 02 00 09 68 8 OFF

Tried two boards. One the power light would turn on. The second, would respond to commands. I give up after 2.