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Stratos-Micra • INSTALLER’S HANDBOOK • Iss. 1
6
7.2 Connecting a Stratos-Micra to a SenseNET/RS485 detector
network
Up to 127 detectors may be linked in a single SenseNET bus, supporting a total length
of wire between adjacent detectors of up to 1.2km.
In the above example, two Stratos-Micra detectors are linked into a 127-detector bus
with a Command Module and a number of Stratos-HSSD 2 detectors. It will be noted
that whereas the Stratos-HSSD 2 units have two input / output buses (1A / 1B and 2A
/ 2B), the Stratos-Micra has only a single such bus (A / B) and therefore each bus ter-
minal has an input and an output wire, compared with a single wire in each terminal
in the Stratos-HSSD 2.
For this reason, it may be easier to join the input and output wires for each bus and
screen connections together and to solder or crimp a single wire or connecting ferrule
to each wire pair so that they are easier to fit into the screw terminals. If this is done it
is recommended that bare wire joints be insulated to prevent possible shorting of the
data bus, which will cause a drop-out of data on the SenseNET bus.
In the above example, there could be a total length of RS485 cable of up to 1.2km
between the Command Module and Detector 3, since these are all on a single bus.
However, Detector 3 is a Stratos-HSSD 2 which has a second communications bus
(RS485 bus 2) and an RS485 repeater. This allows a further total of 1.2km of cable until
the next Stratos-HSSD 2 in the RS485 loop.
In the above example, if detectors 4-126 (not shown) were all of the Stratos-Micra
type then the total length of wiring between detectors 3 and 127 would be limited to
1.2km. However, each additional Stratos-HSSD 2 detector wired up using both RS485
buses would allow an additional 1.2km of cabling to be added to the RS485 loop.
RS485 1A
RS485 1B
SCRN
RS485 2A
RS485 2B
SCRN
A
B
SCN
A
B
SCN
Detector 1
(Stratos-Micra)
Command
Module
Detector 2
(Stratos-Micra)
Detector 3
(Stratos-HSSD)
Detector 127
(Stratos-HSSD)
RS485 1A
RS485 1B
SCREEN 1
RS485 2A
RS485 2B
SCREEN 2
RS485 1A
RS485 1B
SCREEN 1
RS485 2A
RS485 2B
SCREEN 2