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MELSEC-Q
10 HIGH-LEVEL POSITIONING CONTROL
10.3.8 Restrictions when using the NEXT start
The "NEXT start" is a instruction indicating the end of the repetitions when executing
Section 10.3.6 "Repeated start (FOR loop)" and Section 10.3.7 "Repeated start (FOR
condition)".
The following shows the restrictions when setting "6: NEXT start" in the " block start
data".
(1) The processing when "6: NEXT start" is set before execution of "4: FOR loop" or
"5: FOR condition" is the same as that for a "0: block start".
(2) Repeated processing will not be carried out if there is no "6: NEXT start"
instruction after the "4: FOR loop" or "5: FOR condition" instruction. (Note that an
"error" will not occur.)
(3) Nesting is not possible between "4: FOR loop" and "6: NEXT start", or between
"5: FOR condition" and "6: NEXT start". A warning "FOR to NEXT nest
construction (warning code: 506)" will occur if nesting is attempted.
[Operating examples without nesting structure] [Operating examples with nesting structure]
Start block data
Da.12 Special start
command
Start block data
Da.12 Special start
command
1st point Normal start 1st point Normal start
2nd point FOR 2nd point FOR
3rd point Normal start 3rd point Normal start
4th point NEXT
4th point FOR
5th point Normal start 5th point Normal start
6th point Normal start 6th point Normal start
7th point FOR 7th point NEXT
8th point Normal start 8th point Normal start
9th point NEXT
9th point NEXT
••
••
A warning will occur when starting the 4th
point "FOR".
The JUMP destination of the 7th point "NEXT"
is the 4th point. The 9th point "NEXT" is
processed as normal start.