There are three different models of SIMATIC s7-1200: CFU1211C, cpu1212c and cpu1214c. Each can be scaled according to the needs of your machine. A signal board can be added to the front of any kind of CPU to extend the number or analog i/0 without having to change the volume of the controller. The signal module can be connected to the right side of the CPU to further extend its digital or analog i/0 capacity. The cpu1212c can be connected to 2 signal modules, while the CPU121 4C can be connected to 8. All simatic S7-1200 CPUs can be equipped with up to 3 communication modules (connected to the left side of the controller) for point-to-point serial communication.