MODBUS (TCP) This section contains information on the following topics:MODBUS (TCP) for the library versions V2.1 and V3.x of the S7-1200 CPUs (S7-1200)MODBUS (TCP) for the library versions V4.0 and later of the S7-1200 CPUs and as of V3.x of the S7-1500 CPUs (S7-1200, S7-1500)Redundant MODBUS (TCP) communication for library versions V5.0 or higher (S7-1200, S7-1500)