Modbus TCP/IP localhost

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M
M on 11 Oct 2018
Answered: M on 14 Nov 2018
Hi,
I would like to set up a modbus communication using TCP/IP.
In order to test it, I wanted to set the communication between two Matlab sessions on the same computer and set up the communication using local IP address.
To do so, I tested the following:
m = modbus('tcpip', 'localhost');
or
m = modbus('tcpip', '127.0.0.1');
but in both case I get the following error:
Error using modbus (line 96)
Requested transport resource is either in use or does not exist. Unsuccessful open: Connection refused (Connection
refused)
Is it related to a configuration that I have not done on my computer or is it impossible to set up such a communication?
Thanks for your help.
  3 Comments
Ming Yue
Ming Yue on 15 Oct 2018
If you want to transfer data between two MATLAB sessions, you can consider using the "tcpip" connection. Here's an example: https://blogs.mathworks.com/loren/2011/05/27/transferring-data-between-two-computers-using-matlab/.
The example is for sending info from one MATLAB session to another (one direction), so you can setup a server and a client on each MATLAB session with different port number to communicate in both directions.
M
M on 14 Nov 2018
This was indeed a firewall issue. Thanks for your help.

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Accepted Answer

M
M on 14 Nov 2018
This was a firewall issue. Ubuntu has a built-in firewall that one can deactivate using this solution:
<https://askubuntu.com/questions/250775/how-do-i-turn-off-the-firewall-in-ubuntu-12-04>

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