|Applications The Ei428 RadioLINK Relay Module is a device that switches a relay upon receipt of an alarm signal from a suitable Ei smoke/heat alarm. The electrically isolated contacts can be used for many applications such as signalling, turning on lights, etc. The Ei428 is designed to operate with Ei RadioLINK products (Ei168, 405, 405TY, 407, 410 & 411).The Ei428 RadioLINK Relay Module is powered by the 230VAC mains and has rechargeable back-up cells. As supplied the relay operates continuously (i.e. it switches when one of the smoke/heat alarms detects fire and switches back when the smoke clears). When the slide switch is removed to the pulse 'P' position the relay will switch when fire is detected but will automatically switch back after 5 seconds. This is commonly used with warden call systems where only momentary short circuit signalling is required.