Siemens SINUMERIK 840D sl Function Manual page 1062

NC/PLC Interface Signals (Z2)
Several Operator Panels on Several NCUs, Distributed Systems
Second HMI-PLC online interface
This interface utilizes a group signal for both bus types. No distinction is made between OPI
and MPI.
DB10 DBX108.1
FALSE
TRUE
The sign-of-life monitor is switched on by the PLC as soon as a control unit has gone online
to its interface and switched off again when it goes offline.
Sign-of-life monitoring will be enabled:
as soon as control unit or HMI logs on online to its HMI-PLC interface with
S_ACT/CONNECT.
Sign-of-life monitoring will be disabled:
as soon as control unit goes offline.
1. HMI wants to switch over and log off from PLC with
2. PLC acknowledges to HMI with OFFL_CONF_OP/OK
3. Control unit or HMI will be displaced by PLC with OFFL_REQ_PLC/OK
In both instances the PLC detects that a control unit is going offline and waits for the TRUE-
FALSE edge of its HMI sign-of-life signal.
The PLC then ceases to monitor the sign-of-life signal.
19.2.3 Signals from NC (DB10)
DB10
DBX107.6
Edge evaluation:
Signal state 1 or edge
change 0 → 1
Signal state 0 or edge
change 1 → 0
Signal irrelevant for ...
References
1062
E_MMC2Ready
no control unit online to OPI or MPI
Control unit online to OPI or MPI
OFFL_REQ_OP/OK
HMI acknowledges to PLC with OFFL_CONF_PLC/OK
NCU link active
Signal(s) updated:
NCU link communication is active.
No NCU link communication is active.
Systems without NCU link modules.
/PHD/ NCU Configuration Manual
Function Manual, 03/2009, 6FC5397-1BP10-4BA0
Extended Functions