UDT not getting copied completely with CPS instruction

Dear all,

In RS Logix 5000 i m using the CPS instruction to copy an UDT with 8 strings & 1 DINT tag in it. While the rung is executed sometimes i see the complete set of data is not getting copied from source to destination. [It is like only 3, 4 or 5 tags from source gets copied to destination and remaining tags in destination will be of the previous data only]

Why is it so??
Is there any time limit that i should set such that i should keep on executing the rung till it completely copied??
How do i get the confirmation that UDT is completely copied??

Please help me out to get over this problem.

I'm not sure if this is the case but in one program we were receiving a string from an external device. The tag location was cleared before the external source would write the string into our CompactLogix. At first we attempted to copy the string to another tag when the .LEN changed from zero to non-zero. But it had not written all of the DATA section yet. We had to delay the copy for a couple of scans.

bernie_carlton said:

I'm not sure if this is the case but in one program we were receiving a string from an external device. The tag location was cleared before the external source would write the string into our CompactLogix. At first we attempted to copy the string to another tag when the .LEN changed from zero to non-zero. But it had not written all of the DATA section yet. We had to delay the copy for a couple of scans.

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Mr Carlton,
Thank you for your valuable feedback, i'll try putting a delay timer in between 2 executions.

Regards,
Arjun