Profinet Error (PNIO0008): The monitor time of device '...' exceeds 1920 ms.
Reduce the 'Reduction ratio' or 'Monitor factor' of the device mentioned in the error message. This has to be done in the 'Interface' settings of the device.
To open this editor, double-click the error message. Alternatively, you can double-click the corresponding node in the PLANT.
Example:
For more information refer to the tooltips in the 'Settings' editor of the Interface by hovering the mouse pointer on the 
symbol.