Appendix A - Modbus Control via Remote Operator
MCD Modbus Module Instructions
MG.17.F5.02 - VLT
® is a registered Danfoss trademark
12
11.
Appendix A - Modbus Control via Remote
Operator
To control a soft starter via an RS485 serial communications network using the Remote Operator,
connect the Remote Operator to the network as described in the following sections.
11.1.
Grounding and Shielding
Twisted pair data cable with earth shield is recommended. The cable shield should be connected to
a GND device terminal at both ends and one point of the site protective earth.
11.2.
Termination Resistors
In long cable runs prone to excessive noise interference, termination resistors should be installed
between the data lines at both ends of the RS485 cable. This resistance should match the cable
impedance (typically 120
Ω
). Do not use wire wound resistors.
Network Master
RS485
Remote Operator RS485
Soft Starter
(Module) RS485
GND
B8
B6
B7
B3
B1
B2
68 (B8)
69 (B6)
61 (B7)
GND
GND
GND
177HA3
77
.11
120
120
120
120
11.3.
RS485 Data Cable Connection
Daisy chain connection is recommended. This is achieved by parallel connections of the data cable at
the actual device terminals.
11.4.
Remote Operator RS485 Network Connection
Specifications
Input impedance:
12 k
Ω
Common mode voltage range:
- 7 V to + 12 V
Input sensitivity:
± 200 mV
Minimum differential output voltage:
1.5 V (with max loading of 54
Ω
)
11.5.
Using the Remote Operator with MCD 200
+ GND -
RS485 SERIAL COMMS
NETWORK CONNECTION
(MODBUS RTU)
177HA339.13
MCD 200
REMOTE
OPERATOR
RS485
SERIAL PORT
68 61 69
B1 B2 B3 B6 B7 B8
GND
RS485
RS485
NETWORK
GND
+
-
GND
+
-
MCD
-
+
REMOTE
INTERFACE
4-20 mA
ANALOG OUTPUT
B10 B11
4-20 mA
-
+
SUPPLY
SUPPLY VOLTAGE
18 ~ 30 VAC / VDC
1
2
POWER
~/+ ~/-
A1
N2