In the past, conventionally wired systems were common. Nowadays, bus technology and the use of IO systems are established throughout the industry. This reduces the cabling effort significant and saves costs. In particular compact IO modules allow a spatial layout of the system in the field. Sensors and actuators in hazardous areas can be connected directly to the BEx module. Isolating amplifier as well as analogue and digital IO modules are no longer necessary in the safe area.