6F3B0250
Basic Hardware and Function 117
6. Programming Information

6.8 Program execution sequence

The instr uct ions execution sequence is shown below.
(1) They are executed in the seq uence from block 1 through t he final block which
contains the END instr uction (or IRET in an int er r upt program ) .
(2) They are executed in the seq uence from rung 1 throug h t he final rung in a block
(or the END instruction).
(3) They are executed according t o t he 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.
ƒWhen 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 instr uctions execution sequence in which function instr uct ions are included also
follows the above rules. However, f or program execution control instructions, such as
jumps ( J CS) , loops (FOR-NEX T), subroutines (CALL-SUBR-RET ) , it will depend the
specificat ions of each instruct ion.
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