6F3B0250
Basic Hardware and Function
117
6. Programming Information
6.8 Program execution sequence
The instructions execution sequence is shown below.
(1) They are executed in the sequence from block 1 through the final block which
contains the END instruction (or IRET in an interrupt program).
(2) They are executed in the sequence from rung 1 through the final rung in a block
(or the END instruction).
(3) They are executed according to the following rules in any one rung.
•
When there is no vertical
connection, they are
executed from left to right.
‚
When there is an OR
connection, the OR logic
portion is executed first.
ƒ
When there is a branch, they
are executed in the order from
the upper line to the lower line.
„
A combination of
‚
and
ƒ
above.
The instructions execution sequence in which function instructions are included also
follows the above rules. However, for program execution control instructions, such as
jumps (JCS), loops (FOR-NEXT), subroutines (CALL-SUBR-RET), it will depend the
specifications of each instruction.
4321
86
7
2
5431
6
4
5
321
5
3
76421
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