System description
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2.5 System restart behavior
Restart “Restart” refers to the behavior of the safety modules and the optional safe extension mod-
ules after the safety function is triggered and following a return to normal operation. The re-
turn to normal operation is, for example, achieved by unlocking the emergency stop control
device once safe operation is possible again.
With an active restart inhibit, the corresponding safe module output remains in the safe
state. This prevents unintentional restart of a machine controlled via the relevant output.
Error acknowledgment
Manual reset function
An active restart inhibit can be removed by actuating a control device that is connected and
appropriately wired to the base module or to the safe extension modules.
Implementation using safe
blocks
To implement a restart inhibit, use the safety functions in the configuration software which
have the relevant function blocks for activating the restart inhibit.
WARNING: Unintentional machine startup
Restart following power up and when there is no longer a demand of the safety function
can result in unintentional machine startup.
• If you do not want the machine to restart automatically, configure the restart behavior
accordingly in the safety logic.
WARNING: Unintentional machine startup
The acknowledgment of an error can result in a return to the operating state.
• Before acknowledging an error, you must make sure that the acknowledgment will
not cause the machine to switch to a hazardous state.
• When planning the machine or system, make sure that acknowledgment is only pos-
sible if the danger zone is visible.
With the manual reset function, a machine start may not be triggered in accordance with
EN ISO 13849-1.
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