The optical smoke detector D-PE is distinguished by the indicator LED which is clear
in standby and red in alarm. Within the case is a printed circuit board which on
one side has the light proof labyrinth chamber with integral gauze surrounding the
optical measuring system and on the other is the address capture, signal processing
and communications electronics.The detector is designed to be connected to a two
wire loop circuit carrying both data andincoming and outgoing supply via terminals
L1 and L2 in the mounting base. A remote LED indicator requiring not more than 4mA
at 5V may be connected between the +R and -R terminals. An earth connection terminal
is also provided. When smoke enters the chamber the photo-diode signal increases.
The information to the A/D converter is updated once per second. During every poll
cycle this data is sent to the control equipment. If the device is not addressed
within one second of its last polling and the analogue value is greater than the
set alarm level, thealarm flag is initiated and the device address is added to the
data stream. This can provide a location identified alarm from any device on the
loop in approximately two seconds.