Siemens SINUMERIK 840D sl TCU 30.3 Equipment Manual page 50

Networking
6.2 Commissioning TCU
While this message is displayed, operations on the OP with the user authorization can still be
carried out unaffected.
Note
Active switching of an OP to another PCU/IPC is possible
The switchover disable only relates to changing the user authorization on the OPs in a
shadowing group on a PCU/IPC.
This means that active switching away from one OP to another PCU/IPC is not prevented.
Special features
The following special cases should be noted:
• Even if switchover disable is set, the TCU_INDEX field value may change in the PLC. This is the
case under the following circumstances:
– If the OP in possession of the user authorization is actively switched to another PCU/IPC.
– If an m:n switchover is in progress. The HMI program of the incoming PCU/IPC deactivates
– If a PCU/IPC is disconnected from an NCK/PLC in the context of m:n. No HMI program and,
• If a TCU is actively switched over to another PCU/IPC, it can be deactivated there, i.e. it does
not receive user authorization if a switchover disable is set for the destination PCU/IPC.
• With an m:n PCU/IPC switchover – the PCU/IPC is switched to another NCK and, therefore, to
another PLC – the PCU/IPC accepts the switchover disable settings of that PLC.
• The m:n interlock options on the PLC side have priority over the TCU switchover disable, so
that a set TCU switchover disable cannot prevent an m:n switchover. If necessary, the m:n
interference options should be synchronized here with those for the TCU in the PLC. It may,
for example, be practical to set or remove the m:n displacement disable simultaneously with
the TCU switchover disable.
Obtaining user authorization
At a TCU, which has no user authorization, press any key. The operating software does not
evaluate this key; this only serves to request user authorization.
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Depending on whether another TCU takes over the user authorization or whether no TCU
is currently active, the index of the TCU or the PCU/IPC itself (if its directly connected OP
becomes active) is entered, in exactly the same way as when there is a switchover of user
authorization.
This can also be the value 255, if no TCU index is available for the OP. 0 is entered if an OP
is no longer available in the shadow group.
the HMI program which is active on it. Therefore, an OP from the shadow group of the new
(incoming) PCU/IPC must receive the user authorization. The TCU index of this OP is
entered in the TCU_INDEX field.
therefore, no OP with user authorization is then available on the exited NCK/PLC. This is
signaled independently of a switchover disable by entering the value 0 into the
TCU_INDEX field.
Equipment Manual, 03/2023, A5E40874197B AD
TCU 30.3