1053
Model Conversion Instructions Section 3-33
Stack Push Operation
When the leftmost digit (bits 12 to 15) of Of is 9 BCD, DISTC(566) operates a
stack from Bs to Bs+Of-9000. The destination base address (Bs) contains the
stack pointer and the rest of the words in the stack contain the stack data.
DISTC(566) copies S to the destination word calculated by adding the stack
pointer (content of Bs) + 1 to address Bs. The same DISTC(566) instruction
can be used to distribute the source word to various words in the data area by
changing the value of Of.
Each time that the content of S is copied to a word in the stack data area, the
stack pointer in Bs is automatically incremented by +1.
Note Use COLLC(567) to read stack data from the stack area.
Flags
Note In C-series PLCs, the SINGLE WORD DISTRIBUTE (DIST) instruction will
cause the Error Flag to go ON if the content of an indirectly addressed DM
word (*DM) is not BCD, or the DM area boundary is exceeded. DISTC(566)
will not cause the Error Flag to go ON in these cases.
Precautions Once DISTC(566) has been executed with Stack Push Operation to allocate a
stack area, always specify the same length stack area in subsequent
DISTC(566) instructions. Operation will be unreliable if a different stack area
size is specified in later DISTC(566) instructions.
Be sure that the offset or stack size specified by Of does not exceed the end
of the data area when added to Bs.
S
OfBs
Bs+1
Stack area
Stack
pointer
Stack
data area
m words
Size of
stack area
9
m
Bs+ +1
Bs+(m-1)
S is copied to:
Bs + stack pointer +1.
Name Label Operation
Error Flag ER ON if Stack Push Operation is specified, but the stack
pointer data in Bs is not BCD.
ON if Stack Push Operation is specified and the stack
pointer indicates a word that exceeds the stack data area.
Equals Flag = ON if the source data is 0000.
OFF in all other cases.
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