Hochiki FIRElink-100 - Manual (Page 29)

FIRElink-100 – Installation Manual Page 29 of 40
© 2010 Hochiki Europe (UK) Ltd
9-5-0-345/ISS4/OCT10
4.2 Connecting a FIRElink-100 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 FIRElink-100 detectors are linked into a 127-detector bus with a Command
Module and a number of FIRElink-400 detectors. It will be noted that whereas the FIRElink-400 units
have two input / output buses (1A / 1B and 2A / 2B), the FIRElink-100 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 FIRElink-400.
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
FIRElink-400 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 FIRElink-400 in the RS485 loop.
In the above example, if detectors 4-126 (not shown) were all of the FIRElink-100 type then the total
length of wiring between detectors 3 and 127 would be limited to 1.2km. However, each additional
FIRElink-400 detector wired up using both RS485 buses would allow an additional 1.2km of cabling to be
added to the RS485 loop.