Inputs, Outputs, Led indications – Noby UK Noby-420 2-Zone User Manual

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Noby-420 Installation & Programming Instructions Rev3

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Zone Detector Circuits
The Noby-420 requires that each detector zone is terminated with a 4K7 End Of Line resistor. This EOL resistor is
necessary to facilitate open circuit, short circuit and head removal monitoring. The total current drawn by the
detectors on each circuit must not exceed 2mA, which means that 20 detectors can be connected to each zone
(based on a typical 100uA maximum per detector). Similarly, if the detectors are specified at 50uA maximum
current draw, then 40 detectors per zone can be connected.

Class Change Input (Direct Bell Ring)
A positive going input signal to activate on the sounders directly (subject to their isolation status).
The input is non-latching and no indication is given on the display.

Fault Input
An input signal permitting the fault status of remotely connected ancillary equipment (eg. a communication device)
to be indicated on the Noby-420 display panel, causing the Common Fault LED to flash. The polarity of the Fault
Input signal is programmable – see Engineer Programming.


Sounder Circuits
Conventional 4K7 End Of Line resistor monitoring requiring polarised bells or sounders with a combined output
current of 1.25A across the 2 sounder ports. Each sounder circuit is individually fused and monitored.

Fire Relay Output
Double pole voltage free contacts, each rated at 1A@30V, activated upon detection of a zone fire or by the keypad
operated Evacuate function. It is latched until a System Reset. The relay can be isolated - see User Keypad
Functions / Isolation. The Fire Relay Output is not triggered by the Class Change (Bell Ring) Input or from any
activation of a zone that has been programmed as a non-latching zone. The Fire Relay contacts are NOT mains
voltage rated, and any mains voltage switching MUST be done with the addition of a mains rated slave relay.

Panel Sounder (Piezo)
An on-board piezo sounder provides the panel’s internal fire and fault warning tones.
Fire tone = continuous rapid pips.
Fault tone = 4 rapid pips every 4 secs.
Warning Tone = 2 pips every 16 secs.

Aux 24v
A 27.3v (nominal 24v) auxiliary supply fused at 1A (Fuse F1), monitored.

Fault Output
Signals real-time status of System Faults from all sources (zone faults, sounder circuit faults, PSU etc.). It is an
open collector PNP output normally driven to 24 volts, and dropping to 0 volts during a fault condition. The output
has a 470 ohm series limiting resistor.

LED Indications

LED Indications



2 Zone Fire LEDs

Zones alarmed

First To Alarm (winking)

Common Fire LED

One or more zones in fire condition


2 Zone Fault LEDs

Zone/s in fault

Zone/s isolated (slow flash)
Head Removed (intermittent ‘winking’)

Common Fault LED

Any zone fault or system fault

Fault Input terminal active, non-latching

Sounder Fault LED

Sounder fault

Sounders Isolated


Low voltage (< 21 volts), non-latching

Fuses F1 or F4, or Low Volts (latched).



CPU watchdog warning

Power LED

On=Mains OK. Off=Mains absent

Mains restored

Relay Isolate LED


Relay isolated

Function LED

Access code successfully entered


Isolate LED


One or more zones isolated

Test LED


7 day fire test reminder