During the startup, after scanning the system led's, the controller performs a series of self-diagnostic operations. When any faults are detected or the operator has to be informed of any given situation, the self-doagnosis procedure is temporarily interrupted, signalling the event.
The fault signal is made by led's L1, L2 and a message is given on display (if present).

n.	Led ON	System Message (if display present)	Description	Type
1	L1	System Data WRITE ERROR	Indicates that a write error has occurred during the configuration data saving.	B
2	L2	System Data IS RESTORED FROM DEFAULT	Indicates that the configuration data has been restores to the default settings.	C
3	L1 L2	System Data is updated Please verify new data	Indicates that the configuration data has been converted into a new format. Check that the previous settings have been maintained.	C
4	L3	Firmware is updated old: 1K31F10 1.001 new: 1K31F10 1.002	Indicates that a firmware update has been made.	C

When the condition detected allows to continue to the start stage (type C) and waits for the FUNC button or for the F1 key to be pressed to continue the boot procedure.

If not provided with a display, the controller waits 5 seconds before continuing with the startup stage, without waiting for a button to be pressed.

When the situation does not allow to continue the startup stage (tipo B), the controller, if provided with a display, shows the message“PLEASE TURN OFF AND TURN ON THE SYSTEM” and remains in this state until you turn off. If the controller is not provided with a display, the led err flashes continuously.