This function block monitors the relevant safety guard. There are two independent input parameters for two
switches at the safety guard coupled with a time difference (MonitoringTime) for closing the guard.
The function block requires two inputs indicating the guard position for safety guards with two switches
(according to EN 1088), a DiscrepancyTime input and Reset input. If the safety guard only has one switch,
the S_GuardSwitch1 and S_GuardSwitch2 inputs can be bridged. The monitoring time is the maximum time
required for both switches to respond when closing the safety guard. The Reset, S_StartReset, and
S_AutoReset inputs determine how the function block is reset after the safety guard has been opened.
When opening the safety guard, both S_GuardSwitch1 and S_GuardSwitch2 inputs should switch to FALSE.
The S_GuardMonitoring output switches to FALSE as soon as one of the switches is set to FALSE. When
closing the safety guard, both S_GuardSwitch1 and S_GuardSwitch2 inputs should switch to TRUE.
This FB monitors the symmetry of the switching behavior of both switches. The S_GuardMonitoring output
remains FALSE if only one of the contacts has completed an open/close process.
The behavior of the S_GuardMonitoring output depends on the time difference between the switching inputs.
The discrepancy time is monitored as soon as the value of both S_GuardSwitch1/S_GuardSwitch2 inputs
differs. If the DiscrepancyTime has elapsed, but the inputs still differ, the S_GuardMonitoring output remains
FALSE. If the second corresponding S_GuardSwitch1/S_GuardSwitch2 input switches to TRUE within the
value specified for the DiscrepancyTime input, the S_GuardMonitoring output is set to TRUE following
acknowledgment.
The S_StartReset and S_AutoReset inputs shall only be activated if it is ensured that no hazardous situation
can occur when the PES is started.
Configuration and programming
AC500-S Libraries > SafetyBlocks_PLCopen_AC500_v22.lib
30.03.2017AC500-S300
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