CC100 ModBus RTU with Codesys Lib ModbusFB

I’m trying to read out some Sensors via Modbus RTU. Works nicely with WagoAppPlcModbus but I couldn’t get it to work with ModbusFB (, which I’d prefer. The PLC is a CC100 with FW 26, Codesys V 3.5.SP16P2. Has anyone done that yet? Maybe some tweaking on the CLI is required?
Any hints are appreciated!