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• MODBUS connection diagram
These diagrams refer to models
TH-xMxSx1
.
The RS485-MODBUS line has a principal bus to which the various devices are connected (
max 32 devices
).
Use cables with a braided pair + 1 ground wire + shield.
Use the braided pair to connect
A+
and
B-
and the single wire for
GND
which must be connected to each device.
Connect the shield to ground at a single point, preferably near the master.
The cable must be of the MODBUS RS485 data transmission type.
The ends of the cable must be connected with a 120 ohm termination resistance.
To fit the 120 ohm to the regulator, see
“36. Jumper settings” page 104
.
The maximum length of the bus depends on the baudrate and the cable itself.
For a baudrate of 9600, the cable (AVG26 type) can be up to 1000 m long.
Any branch lines must be short, not more than 20 m long. If you use a multi-port tap for n branches, each branch can be
up to 40 m divided by n.
To increase the number of devices on the line or increase the length of the cables, you must install a signal repeater.
Add a signal repeater for every group of 32 connected devices.
Connection without repeater:
GN
D
MODBUS
A +
B
-
Master
es: Cavo Belden 3106A
GN
D
B
-
A +
GN
D
B
-
A +
GN
D
B
-
A +
Slave 1
Slave 2
Slave 32
Max 300m
GN
D
A +
B
-
Master
GN
D
B
-
A +
GN
D
B
-
A +
Slave 1
Slave 32
GN
D
A +
B
-
Repeater
GN
D
A +
B
-
Max 300m
0V 24V
GN
D
B
-
A +
Slave 33
Max 300m
120Ω
termination
ON
120Ω
termination ON
120Ω
termination
ON
120Ω
termination ON
120Ω
termination ON
120Ω
termination ON
230 Vac
+
-
+
-
~
~
230 Vac / 24 Vdc
DC
AC
Connection with repeater:
GN
D
MODBUS
A +
B
-
Master
es: Cavo Belden 3106A
GN
D
B
-
A +
GN
D
B
-
A +
GN
D
B
-
A +
Slave 1
Slave 2
Slave 32
Max 300m
GN
D
A +
B
-
Master
GN
D
B
-
A +
GN
D
B
-
A +
Slave 1
Slave 32
GN
D
A +
B
-
Repeater
GN
D
A +
B
-
Max 300m
0V 24V
GN
D
B
-
A +
Slave 33
Max 300m
120Ω
termination
ON
120Ω
termination ON
120Ω
termination
ON
120Ω
termination ON
120Ω
termination ON
120Ω
termination ON
230 Vac
+
-
+
-
~
~
230 Vac / 24 Vdc
DC
AC
