SINUMERIK operating mode
6.2 Networking
ITC V3, ITC V3 PRO
Operating Instructions, 03/2024, A5E42761061-AF
137
6.2.2.4 Disable switchover between ITC via PLC
Overview
The ITC switchover disable offers the option of dynamically disabling switchover from one ITC
to the next via the PLC when the system is running. For the duration of the disable, a user
authorization request to change user authorization between ITCs will be ignored by the
system and rejected.
The rejected user authorization request causes a message to be output in the dialog line of
the HMI, in the form of a feedback message for the requester. The message disappears after
five seconds.
HMI ↔ PLC data interface
The "switchover disable" function is always active and does not have to be switched on
explicitly. The function is controlled by a data bit in the PLC. The HMI transfers the active OP
to the PLC, thus forming the basis of the control function in the PLC.
The control bits and control information for this function are stored in the m:n data interface
of the PLC. In terms of m:n, this function can be operated separately for the currently
overridden HMIs in both m:n online interfaces (DB19.DBW120 ff for HMI1 and DB19.DBW130
ff for HMI2). If a system is not running an m:n, only the first m:n online interface is used for
this function.
Switchover disable is controlled by a TCU_SHIFT_LOCK bit, managed by the user, on each HMI
in the PLC. The bit address for the first HMI is DB19.DBB126.6 and DB19.DBB136.6 for the
second HMI.
The PLC m:n online interface is expanded so that byte DB19.DBB118 is also assigned to the
first interface and byte DB19.DBB119 to the second. These bytes acquire the index of the
active ITC/OP for the relevant HMI. The byte is called TCU_INDEX. Byte TCU_INDEX is written
to by the relevant HMI, with the TCU index configured for the active ITC.
The TCU_SHIFT_LOCK bit is monitored by the appropriate HMI. A value = 1 triggers the
switchover disable. Switchover is enabled if the value returns to 0. The TCU_SHIFT_LOCK bit
can be set, for example, to the PLC by the user pressing a key or it can be managed by the PLC
user program according to its own logic. The TCU_SHIFT_LOCK bit is managed in the PLC
exclusively by the user; the HMI only accesses this bit in read-only mode.
The HMI writes the configured index of the ITC or IPC whose IFP currently has user
authorization in the shadow group to field TCU_INDEX. If no OP is active, a value of 0 is
entered in TCU_INDEX.
If no TCU index is configured for the active ITC/IFP, the value 255 = undefined is transferred
as the TCU index. This means that the values 0 and 255 may not be configured as the TCU
index.
Configuration
The TCU index is configured on the IPC in the same way as a machine control panel address
(MCP address). The TCU index is set in the "OP Properties" dialog of the "System Network
Center" program.
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