SIMATIC S7-1200, Digital I/O SM 1223, 8 DI/8 DO, 8 DI DC 24V, Sink/Source, 8 DO, Relay 2A SIMATIC S7-1200 Basic Controller - flexible thanks to a wide range of communication options. With signal modules, you can adapt the configuration of your SIMATIC S7-1200 (except CPU 1211C) to suit your individual requirements. A range of digital and analog input, output and mixed modules is available for this purpose, including fail-safe versions. This fine-grained design option saves you space in the control cabinet and optimizes your hardware costs.