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FX5U – FR-F800E – Modbus RTU (Serial) Communication - configuration setup and sample program

FX5U – FR-F800E – Modbus RTU (Serial) Communication - configuration setup and sample program

In this article we will be looking at the Modbus RTU communication (serial) - interconnection between the FX5u PLC and FR-F800E inverter, and the configuration thereof.

In rare cases, ethernet-based communication is not possible, and one has to resort to serial communication. Whilst this communication method is inferior to ethernet-based communication, it is still superior to IO based communication.
In this case we will be looking are Modbus RTU communication protocol.

Setting up the communication.
From the PLC side - in GX Works3 - the Modbus RTU communication settings needs to be finalized.
In this case we will be looking at the build-in (onboard) RS-422\485 serial communication port of the FX5 PLC:
The following applies:

(your advanced settings will obviously, most likely, differ from mine above – depending how your system is being setup)

The next step will be to start with the programming - in GX Works3.
We will use Structured - FB programming:
The block will be the following:

Some additional information: What the labels mean:

Function parameters:

What the error codes are:

The precautions:

In this particular program – it is applied as such;

The Method - Demonstration Video
The following method is applicable as an example:

Part 1:

Part 2:

Part 3:

Additional resources:
PLC example program sample file:
PLCc.gx3 (328.6 KB)

VFD example parameterization sample file:
VSDb.pr4 (69.5 KB)
VSDb.frc2 (17.6 KB)

A800E and F800E Ethernet function manual:
A800-E F800-E ETHERNET FUNCTION MANUAL ib0600628engb.pdf (1.2 MB)

FR-F800E VFD Detailed Instruction Manual
FR-F800-E_-Ethernet_Function_Manual_IB(NA)-0600628-B(11.16).pdf|attachment (1.1 MB)

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