latch indicator Low after High

I have 4 indicators (LEDS) which show the status of 4 items.I have a further
 STATUS Led which indicates if all
4 indicators are high...AND GATE...
 
I want the Status led to go high when all are ok (AND GATE ) but fall low an
d stay low (Latch) if any of the 4 indicators (or all) goes from high state 
to low state and maybe goes high again, so i can see an error has happened a
t some point..
 
Anyone any ideas ?
 
I am using labview 8.0 or a screen picture would help.
 
Thanks,
 
Labtech5555
 
 

Hi labtech, make a boolean shift register holding the state "error has happe
ned". Wire this to your "AND GATE" too... Include a "reset" to set back the 
value in this shift register.

Hi GerdW,
Thanks...Any chance of a quick picture :smileyhappy: to help.
Much appreciated.
Labtech5555

Here is a sample file for you. The main thing to note is that you need to ma
ke sure your values are read inside the while loop... not set as inputs. Wha
t I mean by this is you cannot wire your values into the while loop from the
 outside, they would have t
o be local variables and such, or read from the terminal inside, like I did 
here. I also put a reset into this sample so that you could mess with it and
 see how it works.
It is saved in LV 8.0 format so you can read it.
 
Good Luck,


Latch Fault.vi:
http://forums.ni.com/attachments/ni/170/313400/1/Latch Fault.vi