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Old March 7th, 2018, 05:33 PM   #1
keshik
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AB - ONS and FLL

I'm using a CompactLogix L33ER with v24 of Studio 5000. I've been noticing some odd behavior when I trigger a FLL instruction behind an ONS. It looks like the FLL doesn't always fully execute throughout the array.

For example, using a FLL on a DINT[24] to set all values to zero. I still get the odd value ([18] in this example) that doesn't get set to zero.

Any ideas?
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Old March 7th, 2018, 06:29 PM   #2
Jeev
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What are you setting as source and destination for the FLL? I will usually use 0 for source, the array/structure for destination, and a length of 1.
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Old March 7th, 2018, 06:31 PM   #3
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If it's always the same value, I'd be looking for other things that might be overwriting the data. Look especially for COP or CPS instructions with an incorrect length.

Create a whole new array of the same length and modify your existing logic to point to that array instead of your existing one. Don't change anything else - just the target array - and then see if the symptoms remain.

I'd be very, very surprised to learn of an FLL not "executing properly".
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Old March 7th, 2018, 08:15 PM   #4
keshik
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Quote:
Originally Posted by Jeev View Post
What are you setting as source and destination for the FLL? I will usually use 0 for source, the array/structure for destination, and a length of 1.
Source is 0.
Destination is [0] of DINT[24] array.
Length is 24.
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Old March 7th, 2018, 08:19 PM   #5
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As ASF said, I would then check what's able to access that structure.
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