AS-Interface Safety at Work AS-Interface is a simple and economic wiring system for the first level of industrial communication. An AS-Interface network consists of a control unit, the so-called master, the modules for signal processing, and the associated sensors and actuators. Safety components can easily be incorporated into an AS-i network via AS-Interface Safety at Work. Signals from standard units and safe components are transmitted via a common cable. The fail-safe AS-i PLC is certified for use in safety-related applications up to SIL 3, PL e. AS-i safety monitors are used to monitor safety components in AS-i systems. They monitor the code sequences to be transmitted in the AS-i network. In the case of message deviations or timeouts the monitor ensures the safe state of the system. Safe AS-i modules detect safety-related switching states of 1- or 2-channel E-stops, position switches or door contacts. Using the safe input module safety-related components without integrated AS-i interface can be connected to the AS-i system.