4 Safety Function Blocks
4 - 10
NX-series Safety Control Unit Instructions Reference Manual (Z931)
• This FB monitors the time that two SAFEBOOL inputs are the same and outputs the result on the
SAFEBOOL output when they are different.
• S_ChannelNC and S_ChannelNO are dependent on each other. The evaluation result for both chan-
nels is output.
• When the input for one channel changes so that the two channel inputs are no longer different, the
FB starts monitoring the discrepancy time. An error occurs if a change does not occur that makes
them different again within the monitoring time.
• If S_AntivalentOut is TRUE and the signal for one channel changes, the output immediately changes
to FALSE.
• If an error occurs, make the inputs for both channels inactive (make S_ChannelNC FALSE and make
S_ChannelNO TRUE) 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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