On conveyor lines, optical safety sensors prevent people from entering a danger zone. The material being transported on the conveyor line should, however, be able to pass the safety sensor. To do this, the safety sensor must be bridged temporarily and in a controlled manner for the passage of the transport material. 

Muting and Smart Process Gating (SPG) are two function concepts for this application. 

Muting functions control and monitor the bridging function for material transport on conveyor lines. They use the signals from muting sensors to distinguish between transported goods and persons.

With Smart Process Gating, process control takes place in combination with the system control. A switching signal provided by the PLC and interruption of the protective field by the transported goods are used as triggers for activation of the gating function. No additional trigger sensors are required.