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I have PLC V280-18-B20 and SCADA GE Cimplicity

I have a SW that monitores network assets and traffic, and it noticed (first time) that there was an attempt to communicate from the PLC to SCADA on port 56780
This is the first time that PLC initiates communication with the SCADA
And this is the first time I can see unitronics using port 56780.
The firewall dropped the session, but it looks suspicious to me,
Did anyone expirienced something like this? 

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The port number is defined on both sides of the packet exchange.  A single transaction can have two different port numbers.

Are you using Modbus TCP for you communication?  If so, how is the table set up in the Modbus IP Config block?

Joe T.

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Hi Joe,
Thank you for the answer,

Indeed i am using Modbus TCP communication between the SCADA and the PLC

What do you mean in the second question? I didn't understand.

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Posting your program would be helpful so we're not playing forum-question-pong.

You'll set up a port number for Modbus on the Vision side using the SOCK INIT block.

Then in the MODBUS IP config block you'll set the IP and the port number of the slave-


The slave port number can be whatever you want, but it has to match what you have defined in the slave.

Joe T>


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