Siemens SINUMERIK 840D sl Function Manual page 206

B3: Several operator panels connected to several NCUs, distributed systems - only 840D sl
2.15 Examples
The falling edge combined with the sequence described above signals to the online PLC that
the operator panel has broken off the link to the online NCU. If an MCP is assigned to the
operator panel and activated, it must now be deactivated by the PLC.
The PLC also ceases to monitor the HMI sign of life signal.
Passive operating mode is set in the PLC for the operator panel which has been suppressed.
See "Active/passive operating mode" further below.
Negative: OFFL_CONF_PLC/MMC_LOCKED
Processes that cannot be interrupted are running on the operator panel (e.g. operation via
RS-232 or data transfer between NCU and PCU).
The operator panel remains online to the current NCU.
Operating focus switchover in server mode
A server maintains a permanent link to the NCUs to which it is assigned. The operator can
switch the operating focus from one NCU to another without interrupting the existing link.
If the operator wishes to switch the operating focus to another NCU, the focus PLC and
target PLC must first be interrogated to determine whether they will permit a focus
switchover.
The operator panel first sends the focus offline request signal (OFFL_REQ_FOC/OK) to the
focus PLC.
After a positive acknowledgement (OFFL_CONF_FOC/OK) from the focus PLC, the operator
panel sends query signal ONL_REQ_FOC/OK regarding focus changeover to the target PLC.
After the operator panel has received permission from the target PLC to switch the operating
focus (ONL_PERM_FOC/OK), the operator panel logs off from the focus PLC with
S_ACT/DISC_FOCUS and switches the focus to the target PLC.
The operator panel must finally request active operating mode in the target NCU. The
previous focus PLC must set active operating mode for this HMI-PLC interface after
receiving S_ACT/DISC_FOCUS and deactivate any active MCP assigned to the operating
panel which has gone offline.
See: Active/passive operating mode
Active/passive operating mode
After an operator panel has gone online to an NCU, it can assume one of two different
operating states:
Active mode: Operator can control and monitor
Passive mode: Operator sees header information and the "passive" status identifier.
After switching to an NCU, it first requests active operating mode in the online PLC.
If two operator panels are linked online simultaneously to an NCU, one of the two is always
in active mode and the other in passive mode.
The operator can request active mode on the passive operator panel at the press of a button.
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Function Manual, 09/2009, 6FC5397-1BP20-0BA0
Extended Functions