Omron NX-SL series

3 - 15
3 Safety Standard Function Blocks
NX-series Safety Control Unit Instructions Reference Manual (Z931)
3
SF_TOF
• This FB outputs FALSE when the set time elapses after the timer starts. The time is set in millisec-
onds.
• The timer starts when timer input IN changes to FALSE. Elapsed time ET is incremented as time
elapses.
• When ET reaches set time PT, timer output Q changes to FALSE. ET is not incremented after that.
• The timer is reset when IN changes to TRUE. ET changes to 0 and Q changes to TRUE.
If the timer is started and then IN changes to FALSE before ET reaches PT, the timer is reset.
• The following figure shows a programming example and timing chart for a PT of T#10ms.
Variable abc will change to FALSE 10 ms after variable A changes to FALSE.
• Use the SF_TP instruction for a timer that changes the timer output to TRUE when timing starts and
then changes the timer output to FALSE when the set time is reached.
• Use the SF_TON instruction for a timer that starts when IN changes to TRUE and then changes the
timer output to TRUE when the elapsed time reaches the set time.
Function
Additional Information
PT=T#10ms
In=A
Q=abc
ET=def
FALSE
TRUE
FALSE
TRUE