I have a cheap relays module with ModBus support integrated. I`ve tested it with my debug scripts and it works well. Here is my short manual about it: link (russian lang). Relays on this card could not be accessed as coils and another scheme used instead.
For example if i need to enable relay number 2 i should write value 0x0200 to holding register 2, and i should write 0x0100 if it need to be changed back to open state.
My question is: how to use such kind of control scheme as reular Switch item if it is possible? I have a led lamp connected to such board and i need to enable and disable it with some schedule or manually.