Question about eWON Flexy Historical Data with Modbus TCP Server

I have an eWON Flexy 201 that is communicating with Modicon PLC M340 (CPU part# BMX P34 2020) via Modbus TCP. I tried to create historical data, but wondering why a tag address needs to be shifted by 2 (REAL type) or 1 (INT type) in eWON comparing to PLC tag address? I wasn’t able to find a good manual for my questions.

Please see the attached file for the details of my questions.


Question about eWON Flexy Historical Data with Modbus TCP Server.docx (1.6 MB)

This is likely a case where you are looking at PLC addresses which begin with 0, where the Modbus address begins at one. It’s nothing unique to the Flexy, it’s just how Modbus addressing works.
The REAL type uses 2 registers, hence the shift of 2 registers.

Also, noticed from your document that you have the Modbus TCP Server enabled. This only needs to be enabled if you have another Modbus client that needs to send commands to the Flexy.

You also asked about Tag Visibility and if this needs to be enabled. This applies to the same thing. Only if you are configuring the Flexy to also act as a Modbus TCP server to make data available to another Modbus TCP client. So, to answer your question “Does “Modbus TCP” need to be enabled [under Tag Visibility]” the answer is most likely No.



Thank you for your detailed explanations!


You’re very welcome! Let me know if there is anything else that we can help with.