Modbus TCP

K

Thread Starter

kasar

I'm a beginner with the Modbus TCP

1) How to Transfer the Data from Slave Device to other Slave device using Modbus TCP?

2) is it use special software?

3) What is Device ID?

<b>Moderator's note:</b> I realize these are really basic questions. Can any of the Modbus experts out there point this person to some basic information on Modbus TCP?
Thanks, The Moderators
 
>1) How to Transfer the Data from Slave Device to other Slave device using Modbus TCP?

A modbus master queries/polls a modbus slave with a message requesting data. The slave responsds with its data, or an error message.

>2) does it use special software?

The modbus master is firmware/software application implementing the Modbus protocol, the set of rules that define how communications takes place.

The category of industrial HMI software usually has a Modbus driver option. There are standalone Modbus master software packages that run on Windows. SimplyModbus, Wintech's Modscan32, and Modpoll are 3 that come to mind.

>3) What is Device ID?
A Modbus RTU slave is required to have a unique device ID, an address, which is a number from 1 to 247, to identify itself from other Modbus slaves on the same network, just like your postal address has a street number or an apartment number.

The Modbus standards can be downloaded for free, but the standards are aimed at those writing Modbus code.

For those just needing to implement Modbus, Simply Modbus has a good set of FAQ's on Modbus RTU and Modbus TCP. The basics are covered in Modbus RTU FAQ (so start there), with just the transport differences covered in Modbus TCP FAQ.

http://www.simplymodbus.ca/
 
A

Alberto Pardini

1) Isn't possible to tranfer data slave to slave, You ought to use a master modbus TCP (may be a pc o a plc).

2) if the modbus tcp master is a pc you need to use a driver.

3) Device Id is the slave number in modbus network
 
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