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Instruction and Safety Manual - SMART S
ENGLISH
37
▪
The SMART S gas detectors can be connected to control panels available on the
market having 4-20mA input signals.
▪
Please make sure the control panels are certified according to the applicable
performance standards.
Figure 2 shows the connection of a SMART S detector to a SENSITRON's control panel like
PL4+ or MU+ etc.
N.B.: Control panels accepting 4-20 mA input signals allow the connection
of only one detector per input.
Figure 3: Connection scheme for the 4-20 mA output
5.5.2 RS485 serial output connection
The connection of SMART S to RS485 bus lines should be performed by using a 4-wire
cable, 1 pair for the RS485 bus and 1 for the power supply. It is also necessary that:
▪
Wiring between the detectors and the control panel should be made by using
connection cable EIA RS485: 2 core wires with section 0.22 / 0.35 mm
2
and shield
(twisted pair). Nominal capacity between the wires <50pF/m, nominal impedance
120
Ω
. These features can be found in BELDEN cable 9842 or similar (data
transmission cable in EIA RS485).
▪
Using this wiring, the total length of the line should not exceed 1000 m.
▪
Detectors and output modules are to be wired in daisy chain mode. We
recommend avoiding star or tree mode connection as interference immunity
would be reduced.
▪
Make sure that each multi-polar wire includes just one RS485.
▪
Make sure that a 120
Ω
end line resistor is placed at the beginning and at the end
(on the last detector or output module) of the bus line.
