I have wanted to be able to control the Multiplus via the Cerbo, but the VE.Bus BMS and VE.Bus BMS Assistant on the Multiplus block the Cerbo from changing the invert state between On / Off / Invert Only / Charge Only.
Having done some testing I have reverted to the 2-Wire BMS assistant on the Multiplus and wired the VE.Bus BMS Charge Disconnect to the Aux 1 port and Pre-Alarm to Aux 2, using an Inverting remote on-off cable. I am now able to change the status of the Multiplus from within the Cerbo Screens. The Cerbo correctly shows the VE.Bus BMS status through the relevant MultiPlus screen. Both disconnected at the moment.
I also had a VE.Bus Smart Dongle and found I could modify the status of the Multiplus via my phone as well. When status changed the Cerbo reflected that changed status. So I have a system working as I would like, but not using any functionality of the VE.Bus. I guess I could have achieved the same thing using the smallBMS with pre-alarm.
What I was wondering is if anyone can advise what functionality I might have lost by disconnecting the VE.Bus BMS from the VE.Bus?
I have noticed during my testing today that there is no Alarm or Error that is logged when the VE.Bus BMS signals load or charge disconnect, simulated by disconnecting the signal. The Cerbo clearly isn't triggering on the change of the Multiplus VE.Bus BMS status. I am not sure if it ever did alarm/alert when the VE.Bus BMS was connected via the VE.Bus port to know if I lost functionality. I do know a few weeks back I had a VE.Bus BMS Charge disconnect event and never saw anything on the Cerbo.
Hope people find this useful and it would be good to understand what functionality has been lost by taking this approach and not have the VE.Bus BMS communicating on the bus.