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Modbus RTU communication protocol for VFDs

Jonathan Bullick | November 20th, 2017
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The F5 inverter from KEB America has been a popular drive for many years due to its flexible design, range of available sizes, and lengthy list of options, including communication protocols.


One of these protocols is Modbus®, and the most commonly used version is Modbus RTU. This type of protocol is often seen in industrial automation settings because it’s easy to integrate and use, which is why KEB has made it part of the modular communication feature of the F5 VFD.


Modbus Overview

Modbus RTU uses the RS-485 serial port to transmit communication between machines. Information is sent between a single Master device and the Slave devices as simple,16-bit messages.


When using Modbus RTU data is stored on the Slave devices in four tables – two for coils (on/off values) and two for registers (numerical values).


Customers using Modbus RTU can expect fast and reliable data transmission because of the compact binary messages and CRC error-check mechanisms.


Modbus RTU - KEB F5 VFD


F5 – Scalable Drive Platform

The full family of F5 drives was designed for use in many different industries across a global platform. It’s available in 230, 480, and 690 VAC classes, with scalable sizes from 1 Hp to 1000 Hp. An optional integrated braking transistor can be added for hoisting and regenerative applications, which saves on cabinet space as a separate unit is not required.


Open Loop, Closed Loop, and SCLTM

When it comes to machine control, the F5 has options for open loop, closed loop, or KEB’s unique SCL™ technology. With the SCL control algorithm precise speed and torque control is possible without the use of encoder feedback, and in some cases positioning control can be achieved without an encoder.


Internal positioning functionality is built into the F5 drive for easy coordinated movements over the drive communication bus. The F5 can run both induction and servo motors. These options, along with the communication protocols available, are why the F5 drive is a perfect choice for the system integrator who works with many brands of PLCs and integrated control.


Let us help with your next Modbus RTU Application

KEB has been designing and manufacturing inverters for over 30 years. If you have a question about which F5 drive options best suit your application, contact KEB today.

Modbus® is a registered trademark of Schneider Electric, licensed to the Modbus Organization, Inc.

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