Use UDD to Write Channel Tags to File

Hi, 

The Universal Device Driver (UDD) only interacts with tags that belong to the same UDD channel/device profile. It does not have visibility into tags from other drivers or channels such as Modbus, Ethernet/IP, etc. So a UDD profile cannot directly read another channel’s tag values and write them to a file.

Recommended approach

Use one of the following supported options instead:

Option 1 – DataLogger plug-in (recommended)
This is the simplest method if the goal is exporting tag values to CSV.

Steps:

1. Enable the DataLogger plug-in in KepServerEX.

2. Create a Log Group.

3. Add the tags from the required channel (e.g., Modbus TCP).

4. Configure the output format as CSV or text file.

5. Set the log trigger (periodic or on change).

This approach is designed exactly for writing tag values to files.

Option 2 – Local Historian + export
Store values using Local Historian, then export the data periodically to a file or database.

Option 3 – External client (OPC UA / OPC DA)
Use a small external script or application that reads tags from KepServerEX and writes them to a file.

Summary

UDD is intended for custom protocol/device communication, not for accessing internal tag values from other channels. For exporting tag data to files, DataLogger is the intended and supported solution.

Thanks,