Siemens SINUMERIK 840D sl Function Manual page 807

A machine restart must be impossible until all of the actuated emergency stop control elements
have been deliberately reset by hand.
Emergency stop acknowledgement
The EMERGENCY STOP state is only reset if the interface signal:DB10 DBX56.2
(acknowledge EMERGENCY STOP) is set followed by the interface signal:DB11, ... DBX0.7
(mode group reset).
Hence it can be noted that the interface signal DB10 DBX56.2 (acknowledge emergency stop)
and the interface signal DB21, ... DBX7.7 (Reset) together are set at least for so long until the
interface signal DB10 DBX106.1(emergency stop active) is reset.
Note
The emergency stop state cannot be reset with the interface signal DB21, ... DBX7.7 (Reset)
alone.
(1)
(2)
(3)
Figure 11-1
Basic Functions
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
DB10 DBX56.2 (acknowledge emergency stop) is inoperative
DB21, ... DBX7.7 (Reset) is inoperative
DB10 DBX56.2 and DB21, ... DBX7.7 reset DB10 DBX106.1 (emergency stop active)
Resetting the emergency stop state
N2: Emergency stop
11.5 Emergency stop acknowledgement
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