You can add a third party PLC to the Sofar EMS for Fluvius Telecontrol. The function of this PLC is twofold:
The PLC must be programmed to allow being added as a Modbus TCP slave to the Sofar EMS. See also PLC / Datalogger / Gateway as a slave for more details and the Modbus registers that must be provided.
Adding devices that are controlled by the PLC directly to the EMS Do NOT add a device that is controlled by the PLC directly to the EMS. This could lead to conflicting control signals and doubly counted power values.