SIMATIC S7-1200, digital I/O SB 1223, 2DI/2DQ, DC 24V 200kHz. SIMATIC S7-1200 Basic Controller - flexible due to various communication options. If you only need to expand your SIMATIC S7-1200 CPU by a few inputs or outputs, signal boards are a good alternative to signal modules. Signal boards are directly plugged onto the front of the controller (also possible with CPU 1211C) and are available as digital and analog input, output, and mixed modules. A communication board with an RS 485 interface is also available. Thus, signal boards also allow for subsequent configuration expansion without additional space requirements in the control cabinet.