8 Modbus RTU
8.1 General
136 DC1 variable frequency drive 12/13 MN04020003Z-EN www.eaton.com
8.1.2 COM Port
The electrical connection between the master and the slaves is established
with RJ45 cables. If you use multiple slaves, they will need to be connected
in parallel by using RJ45 cables and splitters.
The DC1 variable frequency drive built-in RJ45 port supports the Modbus
RTU protocol and therefore allows a direct network connection without an
additional interface module. The network cable must be provided at each
physical end (last station) with a bus termination resistor of 120 in order to
prevent signal reflections and the resulting transfer errors.
EASY-NT-R resistors can be plugged into the splitter version.
Figure 85: RJ-45 socket wiring
8.1.3 Enable
In order to use bus mode, there must also be a "high" signal at DI1.
Figure 86: Enable signal for bus mode
8.1.4 Modbus data format
The data format is fixed for DC1 variable frequency drives and cannot be
changed.
• 1 start bit
• 8 data bits
• 1 stop bit
• No parity
Pin Meaning
1 CANopen -
2 CANopen +
3 0V
4 OP bus (operation bus) / External keypad / PC connection -
5 OP bus (operation bus) / External keypad / PC connection +
6 24 V DC power supply
7 RS485- Modbus RTU (A)
8 RS485+ Modbus RTU (B)
DI1
2
FWD
+24 V
1
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