Positioning mode with saving,

Question:

Why is 'home position known' not set after switching on when there is 'Absolute positioning with saving'?

Answer:

Usual function:
In the positioning mode 'Absolute positioning with saving' (C1210 = 2) the homing state 'Home position known' is automatically set after switching on, provided that REF-OK has tripped already with the switching off before.  
In case of first commissioning or when the homing was reset due to certain events (see Manual), a single homing procedure or a setting of home position is to be executed in order to fix the home position of the device and to set REF-OK.

Set trip reset not before initialisation
If REF-OK is not set after switching on, although REF-OK = high when the controller was switched off, the reason for 9300EP ≥ V6.1 (or V2.5) can be that the trip reset input DCTRL-TRIP-RES' is set during commissioning phase.
Therefore, please avoid:

• Connection of output 'STATE-BUS-O' with trip reset input 'DCTRL-TRIP-RES'
• Creation of toggle signal per NOT and connection with 'DCTRL-TRIP-RES'
• Sending of reset per external signal during initialisation

A trip reset is only allowed to be executed in a state ready for operation (DCTRL-RDY = 1). As a remedy the above-mentioned signal sources can be masked with DCTRL-RDY via an AND block in front of the trip reset input.

Note:
Up to 9300EP V2.3 REF-OK was set with each switching on with C1210 = 2, even when the homing was not known before. Therefore, it was eventually unintentionally possible to move without correct homing to the machine. See Doc-ID 20035209