Working as expected, thanks!
I can write the coils. Tested it with The waveshare Modbus POE ETH Relay (https://www.waveshare.com/wiki/Modbus_POE_ETH_Relay)
i’m going to crete a virtual device (probably) per coil. As a thought would that be something to enhance the modbus app with a device per coil? A coil device which you can define a channel and use the existing modbus setup. Something similiar what you did with the slave modbus.
Anyway thanks for the quick response and the enhancement