What is the fine-grained topic of the following text: In the new system, Grenco communicates via a PLC (Modbus TCP) to the IALink100-Modbus, then from the IALink100-Modbus customer communicates Modbus RTU to a GRENCO gateway, which in turn communicates to their sensors in a Refrigeration plant. Only return the topic.
Communication system in a refrigeration plant using Grenco, IALink100-Modbus and GRENCO gateway