PLC Online/Offline

[tamnguyen408]

Hi all,

How do I check PLC online or offline when Program starting up? Thanks in advance

[Archie]

If you did not set SuppressErrorDisplay to True, then most controls will display a message indicating a connection could not be made.

Most of the drivers also have 3 events:

ConnectionEstablished
ConnectionClosed
ComError

You can make event handlers for these events to know when there is a connection issue.

[tamnguyen408]

Thanks, Archie
will take a look tonight

[tamnguyen408]

Hi Archie,

I have not check my program yet.
Please! Give me an example code how to check connection established function call?
many thanks,

[Archie]

The easiest way may be to perform a read in a Try-Catch block:

Code: [Select]

Try
  ModbusTCPCom1.Read("40001")
catch ex as exception
  msgbox "Failed to read." & ex.message
end try

You can double click in a blank area of the form to get to the form load event and put the above code.

[tamnguyen408]

Thank you very much Archie

[tamnguyen408]

Thanks for your help... Archie
It works both VB.NET and C#