A system for controlling a process having a first control device for processing first data, and a first communication interface of a first communication unit designed for receiving the first data, and a second control device for processing second data, and a second communication interface of a second communication unit, designed for receiving the second data. The first communication unit comprises a third communication interface and the second communication unit comprises a fourth communication interface. The third communication interface is connected to the second communication interface and the first processor processes or compares the second data received by the third communication interface with the first data received by the first communication interface. The fourth communication interface is connected to the first communication interface, and the second processor processes or compares the second data received by the second communication interface with the first data received by the fourth communication interface.