Is it possible to read the state of the Aux1 input (closed or open) from the ccgx?
I am not sure which relay you want to read? Which device has the relay?
There is a list of registers to read. There are some relays which can be read (or written).
Check out the register list to see if you can address the relay that you are thinking about.
There is an Excel spreadsheet that you can download to see a list of the registers available:
Victron Centaur and Venus GX 1 Answer