1) PPI protocol: Siemens communication protocol developed for S7-200
2) MPI protocol: not fully supported, can only be used as a slave
3) Free port mode: A user-defined communication protocol for communicating with other serial communication devices (such as serial printers).
The S7-200 programming software Micro/WIN provides communication functions through free port mode:
1) USS instruction library: for S7-200 and Siemens inverters (MM4 series, SINAMICS G110 and old MM3 series)
2) Modbus RTU instruction library: used to communicate with devices supporting the Modbus RTU master protocol
The two communication ports on the S7-200 CPU are basically the same, with no special differences. They can each work in different modes and communication rates; their port addresses can even be the same. The devices connected to the two communication ports on the CPU are not in the same network. The S7-200 CPU cannot function as a bridge.