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65-2643RK-05-04 M2A Transmitter Operator’s Manual
Adding an M2A to an Existing M2 Modbus Installation with Alternate 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 remain installed.
Termination Jumper
The M2A includes a 2-pin termination header (see Figure 4 on page 12) that is used when the M2A is used in a
Modbus system. Every M2A is supplied with a termination jumper (a jumper block) installed onto this header. If
the M2A is not used in a Modbus system, this jumper has no function. When the M2A is installed in a Modbus
system, this jumper must be installed in an M2A that is at the end of a Modbus line. Any M2A in a Modbus
system that is not at the end of a line must have the termination jumper removed (see Figure 12 & Figure 13
below).
Figure 12: Multiple M2As in a Daisy Chain Configuration
Figure 13: Multiple M2As in a Two Branch Configuration
ID = 125
Modbus
Master
Up to 128 M2As can be connected without a repeater
RS-485
RS-485
M2A
Termination
Jumper
Not Installed
M2A
Termination
Jumper
Not Installed
ID = 127
ID = 126
M2A
Termination
Jumper
Installed
ID = 128
M2A
Termination
Jumper
Not Installed
M2A
Termination
Jumper
Not Installed
ID = 1
ID = 4
ID = 127
M2A
Termination
Jumper
Installed
RS-485
ID = 128
Up to 128 M2As can be connected without a repeater
Modbus
Master
M2A
Termination
Jumper
Not Installed
M2A
Termination
Jumper
Not Installed
M2A
Termination
Jumper
Not Installed
M2A
Termination
Jumper
Not Installed
ID = 3
ID = 2
M2A
Termination
Jumper
Installed
ID = 1
RS-485
