Sensitron PL4 +D - Page 42

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Pag. 36
Detectors with 4-20 mA output directly connected to the gas control unit
Figure 10) Connection of the 4 detectors of the gas control unit
Detectors with a 4-20 mA output connected to the STG/IN8S module
The following diagram shows the connection of a gas detector with a 4-20 mA output to a
STG/IN8S input module. During system start-up, make sure that each gas detector reaches
a minimum voltage of 12 Vdc.
Figure 11) connnection of the 8 detectors of the STG/IN8S module
Detectors with RS485 output
Gas detectors provided with RS485 serial communication are connected directly to the
RS485 bus of the PL4 +D gas control unit. The STG/IN8S input module and STG/OUT16S
output module are also connected to the RS485 bus.
4 conductors are needed for this type of connection: two for the RS485 serial and two for the
power supply of devices. For this reason, we suggest that two dierent wires or a single wire
with the features described below, is used.
-V
I8
I7
I6
I5
+V
-V
I4
I3
I2
I1
+V
-V
B
A
+V
REMOTE INPUT
MODULE STG/IN8S
(+V)
(-V)
(S)
Positive
Negative
4-20 mA signal
4-20 mA
analog
gas
detector
+V 1 2 3 4 -V
+
+
V
V
S
S
-
-
V
V