3 Introduction
The present document describes the Modbus/TCP protocol for the CM-Modbus/TCP and CM-
Modbus/TCP-2P (switch function integrated) communication modules. After connecting Modbus/TCP
to the PLC, you can use an additional logic connection from CM-Modbus/TCP to the VPlus software
running on a terminal connected via an Ethernet network.
For Modbus/TCP connection, the frequency inverter must be equipped with the CM-Modbus/TCP or
CM-Modbus/TCP-2P communication module.
The CM-Modus/TCP and CM-Modbus/TCP-2P communication modules are separate components and
must be attached to the frequency inverter. This is described in chapter 5.1 “Assembly”.
Modbus/TCP communication (as described in this manual) requires software version 5.3.0 or higher.
This manual only describes the CM-Modbus/TCP and CM-Modbus/TCP-2P communica-
tion modules. This manual is not to be understood as providing general/basic infor-
mation on Ethernet interfaces or frequency inverters.
General/basic knowledge of the methods and function of Modbus/TCP interfaces and
Modbus/TCP protocol are a prerequisite for understanding and implementing the in-
structions provided by this document.
In some chapters of these instructions, setting and display options via the PC software
VPlus are described as an alternative to the control unit. In this case, VPlus can use
− CM-Modbus/TCP or CM-Modbus/TCP-2P module or
− the serial interface
for communication with the frequency inverter.
The module enables using Modbus/TCP and VPlus via the VABus/TCP protocol at the
same time.
WARNING
With CM-Modbus/TCP or CM-Modbus/TCP-2P, controllers can access all
the frequency inverter.
Changing parameters the function of which is unknown can result in malfunction of the
frequency inverter and dangerous situations in the plant.
Module variants:
There are two Modbus/TCP variants.
CM-Modbus/TCP provides a physical interface for communication via Modbus/TCP. A star-type net-
work topology can be used. An external switch is the star point.
CM-Modbus/TCP-2P provides two physical interfaces for communication via Modbus/TCP. The follow-
ing network topologies are possible:
• Star-type (like in CM-Modbus/TCP)
• Line
10/13
ACU
Modbus/TCP 15
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