Cause
For several PLC boxes with bus data for the same rack and configuration project, you also entered the same slot positions.
This check run only checks PLC boxes at which a configuration project is entered.
Solution
Open the Properties <...> dialog for the corresponding PLC boxes. In the PLC box tab, enter different values for each of the Position (slot / module) fields.
Then start a new check run.
Note:
During this check the property PLC card is placed on head station is also considered. This message is not output if of two PLC cards that have the same slot number one is placed on the rack and the other on the head station. The property PLC card is placed on rack ID means lateral extension, the property PLC card is placed on head station means upward extension.