System Sensor BS5839 Addressing Methods, Dedicated address programmer, Decimal address switches

•Alarm Signal if appropriate

•Status of module output

•Remote test status

•Manufacturer code

Most commonly, each device on the loop will be polled in turn, however to increase speed around a loop, some protocols allow polling of groups of devices on a single communication.

Note that since different manufacturers have their own protocols, it is important to ensure compatibility between the detectors and control panel you intend to use. Some detector manufacturers produce intelligent detectors with different communication protocols for different customers, so two detectors which look virtually identical in appearance may not be compatible. Always check with the manufacturer of the control panel.

1.4. ADDRESSING METHODS

Different manufacturers of intelligent systems use a number of different methods of setting the address of a device, including:

• 7-bit binary or hexadecimal DIL switch

only from one end. If the loop is broken (See figure 1.5.1.), the panel will detect the loss of communications with the detectors beyond the break, signal a fault, and switch to drive the loop from both ends. The system therefore remains fully operational, and can possibly even indicate the area of the break.

In order to give tolerance against short circuits on the loop, short circuit isolators are placed at intervals on the loop. Should a short circuit occur on the loop (Figure 1.5.2.) the isolators directly on either side of the fault will isolate that section. The panel will detect the loss of the devices, signal a fault and drive the loop from both ends, thereby enabling the remainder of the loop to operate correctly and ensuring minimum loss of coverage.

Short circuit isolators are available as separate modules and incorporated into a detector base.

Some products, for example System Sensor’s M200 Series modules, have isolators built into each of the loop devices. With this configuration, since only the section of wiring between the two adjacent devices is isolated there will be no loss of coverage should a short circuit occur.

Intelligent Fire Alarm Systems

• Dedicated address programmer

• Automatic, according to physical position on the loop

• Binary ‘address card’ fitted in the detector base

• Decimal address switches

System Sensor’s Series 200 plus range of intelligent devices uses decimal address switches to define a device’s address between 00 and 99 (See Figure 1.4.1). This is a simple intuitive method, not requiring knowledge of binary or purchase of specialised equipment to set addresses.

24V

SYSTEM FAULT: OPEN CIRCUIT:

Zone 2 Module 01

FIRST FLOOR CANTEEN

SYSTEM OK

FIRE ALARM

FAULT

SYSTEM RESET

INTELLIGENT

FIRE ALARM

CONTROL PANEL

24V

Line break

Panel detects the loss of devices after the break, signals a fault and powers from both ends of the loop to retain full coverage.

3 4 5 6 3 4 5 6

Figure 1.5.1. Open Circuit Fault

Isolating

Impedance

2 7 2 7

1 0 9 8 1 0 9 8

TENSUNITS

Figure 1.4.1 System Sensor decade address switches

-Address 03 selected

24V
SYSTEM FAULT: SHORT CIRCUIT:
Zone 2 DETECTOR 03
FIRST FLOOR CANTEEN
SYSTEM OK
FIRE ALARM
FAULT
SYSTEM RESET	Short Circuit
INTELLIGENT
FIRE ALARM
CONTROL
PANEL 24V

Isolators on either side of the short circuit switch an impedance onto the line to isolate it.

Devices between the two isolators are lost, however the remainder of the circuit still operates correctly.

Isolators automatically reset the line when the short circuit is removed

Differences in the protocol between detectors and modules allow them to have the same address without interfering with each other, and normally address 00 (the factory default setting) is not used within a system so that the panel can identify if a device address has not been set: Hence a total of up to 198 devices - 99 detectors and 99 modules (including call points, sounders, input and output modules) may be connected to a loop.

1.5. SYSTEM FAULT TOLERANCE

Due to the looped wiring method used for analogue systems, they are more tolerant to open and short circuit wiring faults than conventional systems.

Under normal conditions, the loop will typically be driven

Isolating

Impedance

Figure 1.5.2. Short Circuit Fault

Note: This document is based on the recommendations of BS5839 Part 1: 2002. It is intended only as a guide to the application of fire detection systems.

Reference must be made to relevant national and local standards.

5