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Gas density (heavier or lighter than air)
Gas speed emission (flux)
Possible openings in walls or ceilings and air
flows
Composition and shape of the room
Extent of the area to protect
The response time of the sensor is strictly
connected to its position in the room and to the
kind of gas to be detected. For heavy gases like
LPG it is advised to install the transmitter at 20
cm from the ground, while for light gases like
Methane the correct position is 20 cm below the
ceiling. For other gases it is necessary to
evaluate the density in relation to the air
(available on the standard EN60079-20-1) and
place the device accordingly.
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INTERNAL DISPOSITION
──────────────────────────────────
Fig. 5: Internal disposition
1:
+Vin
2:
4..20mA Output
3:
Gnd
4:
Modbus® A
5:
Modbus® B
C1:
Gas sensor connector
C2:
Connector for the expansion board
(optional)
DS1: Not used
DS2: ON = Range Selection Hi (DO NOT alter)
OFF = Range Selection Lo (DO NOT alter)
DS3: Kind of Gas (See table - DO NOT alter)
DS4: Kind of Gas (See table - DO NOT alter)
Gas type setting table
CH4
Gasoline vapors
DS3 OFF
ON
DS4 OFF
OFF
DS5: Leave it OFF
DS6: Leave it OFF
RS1: Rotary Switch 1:
Address setting (x 10)
RS2: Rotary Switch 2:
Address setting (x 1)
L1:
Red LED (Auxiliary)
L2:
Yellow LED (Fault)
L3:
Red LED (Alarm/Pre-alarm)
L4:
Green LED (Supply)
JP4: Function Reset (see text)
JP5: Function Reset (see text)
JT17: Test point for calibration (see text)
JT16: Test point for calibration (see text)
WARNING
The transmitter comes by standard without
any jumper inserted.
SY-N000000SE 034969 310720
──────────────────────────────────
ELECTRICAL WIRINGS (4..20mA)
──────────────────────────────────
+Vin
12-24V In
4..20mA
Control Unit
Fig. 6: Example of 4..20mA connection
The electrical connection is made with a tripolar
copper wire considering the distances indicated
in the table.
It is not necessary to use a shielded cable,
however it is appropriate to maintain the laying
of the cables for the transmitters separated from
mains and/or power cables.
WARNING
The electrical connections must be made
with a tripolar cable with an advised section
2
of 1,5 mm
and with an advised length of 25
m.
Although a shielded cable is not required it
is strongly recommended to lay down the
transmitter connection cables in different
ducts other than the ones for mains or
power cables.
If the transmitter is powered by the control
unit it is necessary to verify in the manual
that the latter is able to supply the correct
powering to the transmitter.
The use of cables with a length greater
than the one advised or with an inferior
section can lead to malfunctions caused by
the excessive drop of tension which could
happen along the cable. This last could
lead to cause powering tension values for
the transmitter inferior to the valid ones.
For example, in the following table are
listed
some
resistance in copper braid cables.
It is absolutely fundamental to verify with a
multimeter, once the system is installed,
CO
LPG
that the alimentation tension present at the
OFF
ON
respective terminals of the transmitter is
inside the tension range valid for the
ON
ON
correct operation.
Moreover, in order to avoid malfunctions it
is necessary to make sure that, even in the
worst conditions of the mains tension
power to the transmitter it is mantained a
sufficient tension value to allow the correct
functioning.
The maximum resistance applicable as a load
on the output line (4..20 mA), when the
powering is at 12V= -15%, is 250 Ohm.
Insulated electric cables resistance in braid
for each km. (according to CEI 20-29 1997)
Cable Section Electric resistence (Ohm / km)
2
0.50 mm
2
0.75 mm
2
1.00 mm
2
1.50 mm
2
2.50 mm
Tab. 4: Typical
copper wires in braid.
S
Gnd
Gnd
values
for
the
electric
36.5 (x 2)
24.5 (x 2)
18.1 (x 2)
12.1 (x 2)
7.41 (x 2)
resistance
values
of
the
Pag. 12/32
──────────────────────────────────
ELECTRICAL WIRINGS (Modbus®)
──────────────────────────────────
+Vin
Gnd
A
12-24V
Gnd
A
MODBUS
Control Unit
Fig. 7: Example of Modbus® connection.
──────────────────────────────────
OPERATION
──────────────────────────────────
Complete in order:
Mechanical installation
Electrical connections
As soon as the power is on and after a brief
ignition of all LEDs, the green LED L4 will
blink. In this phase the sensor is in pre-heating
stage and it is not able to detect any gas.
When this time is elapsed L4 will be in still lit
mode to indicate the normal operation.
──────────────────────────────────
GAS ALARM AND FAULT SIGNALS
──────────────────────────────────
Alarm:
Because this transmitter is simply a converter of
a gas concentration in the respective current
level, the alarm detection, fault and over-range
functions are assigned to the control unit, on
which the threshold limits are set, and to the
Manual, to which the user is advised to refer.
Fault:
The only version of the transmitter for toxic
gases features, among the internal components,
a microcontroller, that constantly checks in time
the validity and the remaining life of the
electrochemical cell. The possible LED signals
are described in the specific section. Although
the control of the sensor life is implemented in
all the models, in the toxic gas sensor (CO) the
remaining life is storaged directly in the sensor
module, while in other cases is storaged on the
base board of the transmitter and so it must be
reset when the sensor is changed for a new
one.
──────────────────────────────────
LED SIGNALS
──────────────────────────────────
Only the L2, L3, L4 LEDs are used for the
current indications: fixed lit for 2 sec when
turning on the transmitter indicates the waiting
for the ADC measurements to stabilize.
L4: Green LED (Powering)
Slow blinking:
It indicates that the stabilization phase is on
after powering, to allow the warm-up. The
sensors, particularly for catalytics need several
seconds for the output to stabilize.
Fast blinking:
When warm-up is finished, the fast blinking
indicates normal functioning of the Modbus®
communication
(if
active);
depends on the polling speed of the master.
Fixed:
When the stabilization and warm-up time are over,
the LED stays steadily on to indicate normal
functioning of the transmitter (without Modbus ®
interrogation).
B
B
®
the
frequency
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