The Context Plus XP95 input/output unit provides two voltage-free, single pole, change-over relay outputs, a single monitored switch input and an unmonitored, non-polarised opto-coupled input.
Compliant with EN54-17 & 18 (2005), the Input/Output Unit supervises one or more normally-open switches connected to a single pair of cables.
It is set to return an analogue value of 4 in the event of an open or short-circuit fault and 16 during normal operation. The status of the inputs is reported by means of two input bits. The change-over contacts are operated by an output bit.
The Input/Output unit is fitted with a bi-directional short-circuit isolator and will be unaffected by loop short-circuits on either loop input or output.
Electrical Considerations
The unit operates at 17-28V DC with protocol voltage pulses of 5-9V. No electrical supply greater than 50V AC rms or 75V DC should be connected to any terminal.
Designed for indoor use only it includes four LEDs, two red and two yellow, which are visible through the front cover of the enclosure. One red LED is illuminated to indicate that the relay is set. The second red LED is illuminated to indicate that the switch input is closed. One yellow LED is illuminated whenever a fault condition (open or short circuit) has been detected. The other LED is illuminated whenever the built-in isolator has sensed a short-circuit loop fault.
The enclosure is moulded from white self-extinguishing polycarbonate.
Specifications
