You cannot enter this type of command instruction (00 00 00 00 00 06 01 05 00 00 FF 00) in the LOGO! user program directly.

LOGO! only recognizes LAD or FBD.

In a network project is only FBD possible.

The LOGO! knows only signed integer for analog functions.

To send the on command for relay 1 of the waveshare you must send the integer value -256.
For the off command for the relay 1 you must send the integer value 0.

See attachment.

You have to keep in mind that LOGO! uses 1-based Modbus addressing, but the Waveshare module uses 0-based addressing.
The Waveshare module's first address is 0. If you want to access HR0 from LOGO!, you have to enter HR1 in the connection table.

On command is FF00 (hex).
FF00 (hex) = 65280 (dec).
65280 unsigned = -256 signed.

Jaime Cortez

 

@AutoGen_97368

Hi,

I'm trying to switch Relais of a connected Waveshare Modbus 30CH Relais:

Manual Waveshare

I need to send a Modbus TCP comand for switching Relais 1 on: 00 00 00 00 00 06 01 05 00 00 FF 00

I want to send that comand when DI1 Input is active. How can I do that?

When I try with my local Modbus Poll it works fine.

From the number of bytes I see, you're referring to the MODBUS TCP frame.

This can be understood as follows:

00 00: (Transaction Identifier, 2 bytes)

00 00: (Protocol Identifier, 2 bytes)

00 06: (Length Field, 2 bytes)

01: (Unit Identifier, 1 byte)

05: (Function Code, 1 byte): 05 corresponde a “Write Single Coil"

00 00: (Coil Address, 2 bytes)

FF 00 (Coil Value, 2 bytes): FF 00 "means that the coil is going to turn on"

To understand more about the protocol, review its documentation.

translated from Spanish using Google Translate.

For using Modbus by LOGO! you don't must know any details of the protocol.

@ AutoGen_97368,

please can you upload your program as a zip file? 

@ AutoGen_97368,

I have make a test with a LOGO! 8.FS4 and a modbus server simulation program.

See attached screen video.