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MAN3038-2
DISCOVERY PRODUCT GUIDE
3
Discovery Feature-Smoke & Heat Detectors
3.1
Response Setting:
Each detector in the Discovery range can operate in one of five response modes, any of which can be
selected from the control panel. Each mode corresponds to a unique response behaviour, which can be
broadly related to sensitivity to fire. Whatever the type of detector, Mode 1 will give a higher sensitivity to fire
than Mode 5. The selection of the most suitable mode depends on the application.
For ionisation and optical smoke detectors, the modes relate to different combinations of smoke response
threshold and response time. For the heat detector, the mode relates to the fixed temperature setting and the
sensitivity to rate-of-rise of temperature. For the optical/heat multisensor, the mode relates to the levels of
smoke and heat sensitivity and to the way in which the responses of the two sensors are combined, although
one mode is a ‘smoke only’ response and another is a ’heat only’ response.
For the CO/Heat Multisensor the two outputs are also combined to provide one output, although one
operating mode is CO only and one is heat only.
The response characteristics of the detectors have been carefully set so that detectors will comply with the
requirements of the relevant part of EN54 in all response modes. The mathematical algorithms embedded in
the detectors are used to carry out changes in characteristics between modes. Since the response
characteristics are defined within the detectors, Apollo takes responsibility for compliance with standards in
different response modes.
The internal signal processing of the detectors is designed so that the analogue value reported is always
close to 25 for a normal condition. The alarm threshold is 55, irrespective of the response mode selected.
Similarly, the alarm flag in the protocol is always set when the analogue value exceeds 55, irrespective of
mode. This simplifies the switching between response modes since the alarm threshold in the control panel
can remain fixed at 55 and the alarm flag is valid in all modes.
The response mode, which is selected through the protocol, is stored in non-volatile memory and will
therefore be retained when the detector is powered down. All Discovery detectors are factory set to mode 3
before shipping. Response modes are defined more fully in the individual detector descriptions. It is,
however, possible for the control panel to read the smoke and heat values of the optical/heat multisensor
detector and the CO and heat values of the CO/ Heat Multisensor separately. This is a highly effective
measure to reduce false alarms. The feature is control panel dependent and the panel manufacturer should
be contacted for further details
.
3.2
User bytes and other stored data:
All Discovery devices contain non-volatile memory, in the form of Electrically Erasable Programmable Read
Only Memory (EEPROM), which is included primarily to store data needed for the correct operation of the
device. However, four bytes of this EEPROM are available to the user and can be accessed by the control
panel through the protocol. This block of non-volatile memory can be used, for example, to store the
installation date, the site code or date of last service. The only restriction on use is that the maximum number
of write cycles should not exceed 10,000 over the life of the device.
3.3
Flashing LED:
All Discovery detectors have two integral LED indicators, which can be illuminated at any time by the control
panel to indicate devices in alarm. When activated, the LEDs will draw an extra 3.5mA from the loop. In
addition to this mode of operation it is possible to enable a flashing LED mode by writing to one of the
memory locations. In this mode the LEDs will flash each time the device is polled.
This facility is available on all Discovery detectors and the manual call point. Discovery detectors and call
points are factory set to non flashing mode.
