Rockwell Automation MSR42 Curtains Configuration and Diagnostic Software Tool User Manual - Manual (Page 30)

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Light Curtain Multi-Function Control Module User Manual
Original instructions
5.4.8. Safety override
Certain applications in practice require that the safety light curtain protective field needs to be overridden “manually” without the MSR42 safety
contacts opening. A typical example of such an application is during the installation or service of a machine. It should be possible to run the machine
even if the protective field is interrupted.
If the risk analysis of the application shows that it is necessary to monitor the function of the override lamp during such a safety override condition, this
feature may be configured (
Figure 39).
Indication of Override
If Override is configured then a lamp must clearly indicate this to the operator. The MSR42 control module monitors the connection of the lamp. If this
lamp is defective or not connected, the MSR42 controller will immediately cancel the override function (i.e. return to the safe mode).
However, according to the risk analysis of the application, the monitoring of the indication lamp may be deactivated ( Figure 39). The lamp will still be
activated if override is selected, but it is no longer monitored.
Important safety notice:
The Override lamp must be mounted near the protective field, clearly visible to the operator.
5.4.8.1. Override Micro 400 Safety light curtain
Figure 39: Specification window “Safety override”
Two methods can be selected to override a Micro 400 light curtain:
1. Key Switch 2 Channel (A maintenance key or service enable switch is typically used to initiate a “Safety Override” mode.)
2. PNP signals (cross fault monitored) (For special applications it is also possible that the two safety override switch signals are replaced by two
safety signals (e.g. a safety PLC gives a maintenance signal that the machine should run at a lower speed for service purposes). In such an
application a key switch must still be placed in series with the two safety signals. Only when the key switch is activated and the safety signals are
“high”, will the safety override function be active.)
The opening of only one contact will lead to a stop of the override function within the reaction time of the MSR42 control unit. The override function
can only be re-activated after both contacts (or signals) have been opened (or deactivated) at the same time.
For PNP signals:
It must be made sure that a short circuit of one of these safety signals to ground, to +24V DC or between each
other must be detected by the external safety controller and once detected this external safety controller has
to immediately stop the dangerous machine movement.
When the safety prevention switch contacts are closed and the MSR42 control unit is powered up, the safety
override function will be immediately active.