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Input/output unit with isolator, 55000-847IMC

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.


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.


Minimum loop operating voltage in normal  conditions: 17V DC

Maximum loop operating voltage: 28V DC

Max. current consumption at 24V DC no protocol  Switch-on surge, max 150ms: 3.5mA  Quiescent, 20kW EOL fitted: 1.25mA

Switch input closed ‘switch closed’ LED on: 2.5mA

Switch input closed (LED disabled): 1.5mA  Any other condition (max 2 LEDs on): 3.5mA  Relay operated: 2mA

Switch input monitoring voltage (open-circuit  condition): 9–11V DC

Maximum cable resistance: 50W

Opto-coupled input

Maximum voltage: 35V DC

Impedance: 10kW

Relay output contact rating at 30V AC or DC  (inductive or resistive): 1A

Relay output wetting current at 10mV DC: 10µA

On resistance 0.2W

Maximum continuous current: 1A  Maximum switching current: 3A  Maximum load: 20 Context Plus detectors  Operating temperature: –20°C to +70°C  Humidity (no condensation) : 0–95% RH  Shock, vibration and impact: to GEI 1-052  IP rating: 54

Radiated and conducted RF emissions to:  BS EN 50081-–1 & 2

Radiated and conducted RF immunity to:  BS EN 50130–4

Dimensions of Input/Output Unit (surface mount):

150 x 90 x 48mm; Weight: 240g


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