Reer MZERO Installation, Use And Maintenance Manual page 81

STAND ALONE PROGRAMMABLE SAFETY CONTROLLER
Figure 38 - Traces relative to "Guard Lock" block operation in the "Mandatory gate opening mode".
In "Mandatory gate opening" mode, the "Guard_lock" operator indicates an error
condition if it does not detect that the gate has been opened following a request to
unlock the guard lock. This concept is highlighted in the figure below
(Figure 39). In this case, the "Enable Error out" option has been selected in the diagram in
Figure 37, so that the error is shown in the graph.
As previously described, the operator requests unlocking of the guard lock, but the door
is never opened, and this condition is indicated by the "FBK_GATE" signal, which stays at
LL1. Thus, when the guard lock unlocking/locking cycle ends, at time "E", the "Guard_Lock"
operator switches the status of the "ERROR" signal from LL0 to LL1.
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