Cause

The same full CPU name is used more than once within the same EPLAN project. This full CPU name consists of the values of the properties Configuration project, PLC station: ID and the CPU identifier that are separated by a point as the separator.

Solution

1. Locate the PLC box of the CPU in the schematic using the Go to (graphic) functionality that is provided by the popup menu of the Message management dialog.
2. Open the property dialog of the PLC box.
3. Bring the PLC structure data tab to the front.
4. Change the value of the CPU: Name [1] field in the properties table.
5. Click [OK].
6. If required, start a new check run.