F_trig / r_trig

[wicing]

I wonder if anyone knows the time-lenght of the output-pulse from a f_trig or r_trig function.
If I use one of the above in one POU to activate a global BOOL and use the global BOOL as a pulse in a different POU, is there a risk that the I miss the pulse in the second POU?

I use wago 750-8100 for this project.

 

[kolyur]

I wonder if anyone knows the time-lenght of the output-pulse from a f_trig or r_trig function.
If I use one of the above in one POU to activate a global BOOL and use the global BOOL as a pulse in a different POU, is there a risk that the I miss the pulse in the second POU?

I use wago 750-8100 for this project.

The time length of the output bit is one processor scan. Basically the trigger function activates the bit when it sees a rising or falling edge, then deactivates it the next time the function executes, i.e. at the same point in the subsequent scan. So as long as all of your logic is executed sequentially--even if it's in different subroutines--there's no chance that you could "miss the pulse". If you use the output bit to trigger a second bit (with a standard := assignment), that bit will be on for one full processor scan also.

This would not necessarily hold true if your POUs are across multiple PLC tasks, or if they are executed conditionally.

 

[wicing]

Thanks a lot!