Technical data

Copy and Block Functions
System Software for S7-300/400 System and Standard Functions - Volume 1/2
3-4 A5E00709327-01
3.2 Uninterruptible Copying of Variables with SFC 81
"UBLKMOV"
Description
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
• Runtime irrelevant blocks
You can copy a maximum of 512 bytes of data. Note the CPU-specific restrictions;
you can find them in the instruction list, for example.
The source parameters can also be included in a the load memory of an unlinked
data block (DB, compiled with the keyword UNLINKED)!
Interrupt ability, Interrupt Reaction Times
Copying cannot be interrupted. Remember that if you use SFC 81 "UBLKMOV,"
this can increase the interrupt reaction times of your CPU.
Parameter Declaration Type Memory Area Description
SRCBLK INPUT ANY I, Q, M, D, L Specifies the memory area to be copied
(source area). Arrays of the data type
STRING are not permitted.
RET_VAL OUTPUT INT I, Q, M, D, L If an error occurs when the function is
being executed, the return value contains
an error code.
DSTBLK OUTPUT ANY I, Q, M, D, L Specifies the memory area to which the
data will be copied (destination area).
Arrays of the data type STRING are not
permitted.