Halma Ampac FastSense 25, Руководство по установке и эксплуатации

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MAN2285-9
Page 26
8.2 Connecting
FastSense25 to a SenseNet 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.
RS485 1A
RS485 1B
RS485 2A
RS485 2B
SCREEN
SCREEN SCREEN
A
B
SCREEN
A
B
RS485 1A
RS485 1B
RS485 2A
RS485 2B
SCREEN 1
SCREEN 2
RS485 1A
RS485 1B
RS485 2A
RS485 2B
SCREEN 1
SCREEN 2
Command Detector 1 Detector 2 Detector 3 Detector 127
Module (FastSense25) (FastSense25) (FastSense PLUS) (FastSense PLUS)
In the above example, two FastSense 25 detectors are linked into a 127-detector bus with a Command Module
and a number of FastSense PLUS detectors. It will be noted that whereas the FastSense PLUS units have two
input / output buses (1A / 1B and 2A / 2B), the FastSense 25 has only a single such bus (A / B) and therefore
each bus terminal has an input and an output wire, compared with a single wire in each terminal in the
FastSense PLUS.
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 FastSense PLUS 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 FastSense PLUS in the RS485 loop.
In the above example, if detectors 4-126 (not shown) were all of the FastSense 25 type then the total length of
wiring between detectors 3 and 127 would be limited to 1.2km. However, each additional FastSense PLUS
detector wired up using both RS485 buses would allow an additional 1.2km of cabling to be added to the
RS485 loop.