Hello,

I have some thing to share about SFC20 issue.

1- It is possible for SFC20 to be interrupted by
high priority OS tasks.For this case, you have
option of using " SFC 81 "UBLKMOV"", section3.2
of this manual:
http://support.automation.siemens.com/WW/view/en/44240604

With SFC 81 "UBLKMOV" (uninterruptible block move), you can copy the contents of a memory area
(= source area) consistently to a different memory area (= destination area). The copy operation
cannot be interrupted by other operating system activities.
Using SFC 81 "UBLKMOV," you can copy all memory areas except:
• The following block types: FB, SFB, FC, SFC, OB, SDB
• Counters
• Timers
• Memory areas of the peripheral I/O areas

2-To be sure of error -free execution , you can check BR"status bit"
of CPU in STL or ENO in LAD or FBD.If BR is still active (active ENO)
right after execution of SFC20, data sent without error in destination.

Finally, if you have any problem regarding your codes related
to SFC20,Upload a snapshot or the whole project here for further
analysis.

Best regards
Hamid Hosseini