Modules of this type are often used to monitor machine doors or covers, and stop the machine whenever the housing is opened. The safety output release does not depend on the order in which the normally open contacts are closed. Two versions, 47013101 and 47013401, feature additional LEDs that indicate sensor status and operating voltage. The units’ 4-pin wire contacts are pluggable and can be coded to prevent accidental mix-ups. The Central Control Unit Series 47013x feature a narrow construction, with a width of just 22.5mm. They comply with Category 3 of EN 954-1.