65-2643RK-05-04 M2A Transmitter Operator’s Manual
41
Recommended Modbus Wiring
The recommended Modbus wiring for the M2A is illustrated in Figure 10 below. In this configuration, 5 wires
are used for wiring the M2A into a Modbus system. Figure 10 also illustrates typical alarm device wiring. The
ground jumper must be removed in this wiring configuration.
Figure 10: Recommended Modbus Wiring
Adding an M2A to an Existing M2 Modbus Installation with Recommended Wiring
An M2A can be wired into an existing M2 Modbus system. The shape of the terminal PCB will be different but
the wiring connections are identical and the ground jumper on the M2A must still be removed.
Alternate Modbus Wiring For Existing Installations
Although the wiring shown in Figure 10 is recommended, it is possible to wire the M2A into a Modbus system
with only 4 wires in situations where a pre-existing system is being replaced and wiring is already in place. This
should only be done if wiring for a system that is being replaced is already installed and it is not practical to run
another wire. See Figure 11 below for this wiring configuration. In this configuration, the wire between the “C”
terminal on the M2A and the Common terminal on the Modbus controller is omitted. Instead, the Common
terminal on the Modbus controller is connected to the “-” of the 24 VDC power supply.
The ground jumper must
be installed in this wiring configuration.
Figure 11: Alternate Modbus Wiring
-
S
+
+
PW
R
/S
IG
PW
R
/S
IG
+
-
S
+
RS
4
8
5
A
B
C
A
B
C
RS
4
8
5
+
-
10-30 VDC
Input
Terminals
Modbus Controller
Remove Ground Jumper
Power Supply
Common
D1
D0
+
C
NC
N
O
AL
A
R
M
1
C
N
C
N
O
AL
A
R
M
2
C
N
C
N
O
FA
IL
See
Detector
Wiring
C
NC
N
O
AL
A
R
M
1
C
N
C
N
O
AL
A
R
M
2
C
N
C
N
O
FA
IL
To
Additional
M2As
Remove
Ground
Jumper
TO
X
IC
O
X
Y
+
TO
X
IC
O
X
Y
See
Detector
Wiring
+
-
S
+
PW
R
/S
IG
+
-
S
+
PW
R
/S
IG
A
B
C
RS
4
8
5
A
B
C
RS
4
8
5
+
-
10-30 VDC
Power Supply
Modbus Controller
D1
Common
D0
Input
Terminals
TO
X
IC
O
X
Y
C
N
C
NO
AL
A
R
M
1
C
N
C
NO
AL
A
R
M
2
C
N
C
N
O
FA
IL
See
Detector
Wiring
C
N
C
NO
AL
A
R
M
1
C
N
C
NO
AL
A
R
M
2
C
N
C
N
O
FA
IL
To
Additional
M2As
+
TO
X
IC
O
X
Y
+
See
Detector
Wiring
