ESS021 Addressable warning sign Visual/Audible alarm sign with certified EN54-3 audible signal capability. The sign comprises an EM312SR module, it must be connected to the loop and to a 24Vdc power source. This device, as well as activating warning signals, provides an input for a conventional alarm callpoint and a relay for the control of an electromagnetic stop. The ESS021 provides a cost-efficient solution for the complete control of a fire exit (REI Door).