

This article explains how to connect a safety beam with a normally-closed (N/C) output to a Centurion CP77 controller using an external 12V relay.
The standard CP77 Infrared Beam (IRB) input is designed for a normally-open (N/O) contact. When interfacing a safety beam that provides an N/C output, an external 12V relay can be used to convert the N/C signal into the required N/O signal for the CP77.
This arrangement allows the CP77 to receive the appropriate safety-beam signal while maintaining the required electrical interface between the beam and controller.

