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65-2658RK-CH4-4 M2A Transmitter Operator’s Manual
Recommended Modbus Wiring
The recommended Modbus wiring for the M2A is illustrated in Figure 9 below. In this configuration, 5 wires are
used for wiring the M2A into a Modbus system. Figure 9 also illustrates typical alarm device wiring. The ground
jumper must be removed in this wiring configuration.
Figure 9: 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 9 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 10 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 10: Alternate Modbus Wiring
Power Supply
Remove Ground Jumper
10-30 VDC
-
+
Modbus Controller
Input
Terminals
D0
D1
Common
See
Detector
Wiring
To
Additional
M2As
C
N
C
NO
AL
A
R
M
1
C
N
C
NO
AL
A
R
M
2
C
N
C
NO
FA
IL
-
S
+
A
B
C
RS
4
8
5
PW
R
/S
IG
R
W
G
B
LE
L
-
S
+
A
B
C
RS
4
8
5
PW
R
/S
IG
R
W
G
B
LE
L
C
N
C
NO
AL
A
R
M
1
C
N
C
NO
AL
A
R
M
2
C
N
C
NO
FA
IL
Remove
Ground
Jumper
See
Detector
Wiring
Power Supply
10-30 VDC
-
+
To
Additional
M2As
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
-
S
+
A
B
C
RS
4
8
5
PW
R
/S
IG
R
W
G
B
LE
L
-
S
+
A
B
C
RS
4
8
5
PW
R
/S
IG
R
W
G
B
LE
L
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
D1
Modbus Controller
Input
Terminals
D0
Common
See
Detector
Wiring
