Each SIMATIC S7-1200 CPU can be expanded with as many as three communication modules. 
The RS485 and RS232 communication modules are suitable for serial, character-based point-to-point connections. 
The library functions USS Drive Protocol and Modbus RTU Master and Slave Protocol are already included in the SIMATIC STEP 7 basic engineering system.

Integration of identification systems

Using the RF120C communication module all SIMATIC identification systems (RF200/300/600 and optical reader system MV400) can be connected directly to the SIMATIC S7-1200. A reader can be connected to a RF120C via the point-to-point connection. The RF120C also provides a library with application blocks that are very easy to handle. Configuration is carried out via the TIA Portal.