modbus rtu communication

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Ajay Soni
Ajay Soni on 24 Feb 2011
Commented: Eric Wetjen on 15 Mar 2022
hi, i want to know that is it possible to connect the matlab with a plc using modbus rtu protocol using m-code if yes then how can we do it and how can i get the proper format of the sending data to plc.
please help me.
Eric Wetjen
Eric Wetjen on 15 Mar 2022
In R2022a, Modbus RTU support is now available in the new Industrial Communication Toolbox.

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Answers (6)

Gustavo Dacanal
Gustavo Dacanal on 9 Sep 2016
Here is my code to Modbus RTU DataLogging. It works for me for a heater controller. (model NOVUS N1100). tks -Gustavo
clear all;
close all;
% remove any remaining serial objects to prevent serial issues
% Initialize Serial Port Object [s]
s = serial('COM3');
% Specify connection parameters
%Open serial connection
% Specify Terminator - not used for binary mode (RTU) writing
s.terminator = 'CR/LF';
% Set read mode
%Check Open serial connection
% RUN and COPY hexadecimal array from SimplyModbus software as example
% SimplyModbus IN [01 03 00 00 00 03 05 CB]
% Observe the output as result from SimplyModbus software
% SimplyModbus OUT [01 03 06 01 90 01 16 00 00 00 81]
request = uint8(hex2dec(['01'; '03'; '00'; '00'; '00'; '03'; '05'; 'CB']));
fwrite(s, request); %start in dec
outdec = fread(s);
outhex = dec2hex(outdec);
outstr = reshape(outhex.',1,[]); %return line string of array hexadecimal e.g.: '010306019000EB0000908D'
SP = hex2dec(outstr(7:10))*0.1 %Variable SetPoint de controler
PV = hex2dec(outstr(11:14))*0.1 %Real temperature PV
MV = hex2dec(outstr(15:18))*0.1 %Variable MV
clear s

Robert Garnett
Robert Garnett on 8 Dec 2012
Hi Steve,
It is possible and easy. The modbus spec is well described on the site. I have written C Simulink functions for xPC and also a matlab m code system which runs in an M code gui.
I wrote the code for a power meter and also interfaced it with an ARM 7 processor which simulated a boiler cleaning water cannons. I wrote a interrupt driven program for the ARM which was mostly C with a little bit of assembler. I used the simulink coder (then the RTW) to generate the functionality of the cannons. It worked very well.
The S functions were the hardest to write because I was doing it for the xPC platform which doesn't have a debugger. S functions aren't the easiest things to understand, but once you get to grips with them by looking at the many examples available they are very doable.
I haven't bothered writing a modbus ASCII interface because it is limited and the RTU version with appropriate data formating will handle ascii characters anyway.
I can send you copies if you like.
My email addresses are:

Steven Edmund
Steven Edmund on 7 Mar 2011
I believe it should be possible to use the RTU protocol, however it will take a significant re-work of the code that you are referencing. has some good resources for this, the best I found was this PDF. The primary thing with RTU is that you will have to change the coding and byte construction, the framing of the message and the checksum from an LRC to a CRC. Best of luck, -Steve

W. on 4 Apr 2012
I know this is an old post, but if you are still having problems, see my posing File ID: #36022. I used RTU to communicate with a power meter.

Raimundas Steponavicius
Raimundas Steponavicius on 3 Mar 2017
Does anybody know how to implement MODBUS ASCII or RTU communication with MATLAB on the slave computer. I cannot find anything on that ! All cases (posts) that I found are when MATLAB is used as the host/master. Any info or references would be appreciated a lot.

Dogukan Kucukler
Dogukan Kucukler on 27 Jun 2018
Hello friends,
I am currently looking for a solution how to implement slave device to Industrial Control Toolbox on MATLAB by using MODBUS RTU Protocol (RS485).Is there anyone that can help me about it ? Is there any tutorial or pdf to understand these process completely ?
Thank you, DK
  1 Comment
Shumin Jiang
Shumin Jiang on 30 Sep 2018
HEY dude, have you done this? now I am in the exactly same situation as you are. Do you have have any tutorial or any other demos to understand this process? Many thanks!

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