GX IEC Developer task-pool problem

[IanJohnston]

Hi, GX IEC Developer (ver 4 & 5) & Q02 cpu. I decided I needed a POU that will only run say every 4000ms (4 secs), so I created a new entry in the task pool and specified:- Prio=10 Interval = T#4000ms I'm finding that the POU doesn't run for 4 secs after everything else is running, but from that point onwards it seems to be running full whack. I'm using a Mits GOT930 terminal which works by way of direct memory access, so the parameters on the LCD are actual PLC memory locations. I can see them delay for 4 secs but then continually refresh. There's no other POU's updating the same memory locations. Any ideas? Ian.

[navillusi]

The problem with the tasks is that once you enable them, you must disable them when finished. Here is how I would tackle this, assuming that you want your subroutine to run every 4 seconds for one scan only.. In your main continuous task, create a 4 second timer which, when done will set a BOOL which you have declared in the GVL (lets call it Task_1) Create a new task within the task pool which will run your "one scan" POU In the task attributes box you will set Event = Task_1, Interval=0, priority=10. This will then enable the POU after a 4 second delay, all you will need to do now is turn it off after 1 scan. Therefore at the end of your "one scan" POU, you will turn off or reset the timer which is still enabled in the main program. I am sure there must be a simpler way than this, but it's the best I can think of. Regards Ian