Kidde Stratos-HSSD 2 - Page 41

Page 41
Stratos HSSD-2 • INSTALLER’S HANDBOOK • Iss. 12
8.2 Connecting a detector network to a command module
120 ohm screened twisted pair such as Belden 9841 24 AWG should be used for all
loop connections. The RS485 A and B wires should be taken through a ferrite (supplied)
with a single loop illustrated for the power wires in section 5.3.3. The total length of
interconnecting cable between adjacent Stratos-HSSD 2 detectors in the loop should
not exceed 1.2 kilometres.
The detectors are connected using the RS485 connections on the terminal block
(see sections 5.3.1/5.3.2) RS485 1A and 1B are the signal connections for bus 1 and
RS485 2A and 2B are the signal connections for bus 2. SCREEN 1 and 2 are the screen
connections for buses 1 and 2 respectively.
For the Command Module, the RS485 1A and 1B connections may be thought of as the
‘Send’ lines, and 2A and 2B the ’Return’ lines. For each detector on the loop, the 1A and
1B connections may be thought of as the lines from the previous detector on the loop
and the 2A and 2B connections the lines to the next detector in the loop.
It should be pointed out that loop connections such as above are only needed for a fully
fault-tolerant network where full isolation is required between detectors. If all detectors
are operating within the same zone a series connection can be used where the output
from the Command Module is taken from the Bus 2 terminals and the last detector in
the loop does not require to be connected back to the command module as shown
below. In this example, the Command Module will not be able to monitor the network
for communications problems but less wiring is required.
8.2.2 Non-fault tolerant serial configuration
8.2.1 Fault tolerant detector loop configuration
RS485 1A
RS485 1B
SCRN
RS485 2A
RS485 2B
SCRN
RS485 1A
RS485 1B
SCREEN 1
RS485 2A
RS485 2B
SCREEN 2
Detector 1Command
Module
Detector 2 Detector 127
RS485 1A
RS485 1B
SCREEN 1
RS485 2A
RS485 2B
SCREEN 2
RS485 1A
RS485 1B
SCREEN 1
RS485 2A
RS485 2B
SCREEN 2
RS485 1A
RS485 1B
SCRN
RS485 2A
RS485 2B
SCRN
RS485 1A
RS485 1B
SCREEN 1
RS485 2A
RS485 2B
SCREEN 2
Detector 1Command
Module
Detector 2 Detector 127
RS485 1A
RS485 1B
SCREEN 1
RS485 2A
RS485 2B
SCREEN 2
RS485 1A
RS485 1B
SCREEN 1
RS485 2A
RS485 2B
SCREEN 2