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4 Safety Function Blocks
NX-series Safety Control Unit Instructions Reference Manual (Z931)
4
SF_Equivalent
• This FB monitors the time that two equivalent SAFEBOOL inputs are not the same and converts the
inputs to one SAFEBOOL output.
• S_ChannelA and S_ChannelB are dependent on each other. The evaluation result for both channels
is output.
• When the input for one channel changes so that the two channel inputs are no longer the same, the
FB starts monitoring the discrepancy time. An error occurs if a change does not occur that makes
them the same again within the monitoring time.
• S_EquivalentOut is TRUE if the conditions for both changes are met and FALSE if the conditions are
not met.
• If an error occurs, make the inputs for both channels inactive (make S_ChannelA and S_ChannelA
FALSE) to reset the FB.
•Set DiscrepancyTime to a value that is longer than the safety task period.
Refer to the NX-series Safety Control Unit User’s Manual (Cat. No. Z930) for application methods for
DiscrepancyTime.
Precautions for Correct Use
This FB does not have a restart interlock. You must connect it to a FB that has a restart inter-
lock.
Function
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