Mitsubishi MELSEC-A Series Programming Manual page 184

6. BASIC INSTRUCTIONS
The following program is written before END or FEND of the main and subsequence programs.
Ladder example
Timing chart
OFF No switching between the main and subsequence programs. (4), 5), 11))
Operation
The main sequence program is only switched to the subsequence program, then back to the main sequence
ON
depending
program on the first leading edge of the CHG instruction execution command (X0). (2))
on ON/OFF
OFF
of X0
↓
Switched between the main and subsequence programs ( 1), 6), 12))
ON
When the CHG instruction is executed, END processing (e.g. timer timing, counter counting, WDT reset) is
Remarks
performed for the current program and operation is started from step 0 of the other program.
The following program is written before END or FEND of the main and subsequence programs.
Ladder example
Timing chart
OFF No switching between the main and subsequence programs. (4), 5), 11))
Operation
CHG instruction is executed every scan and switches between the main and subsequence programs. (2), 3),
ON
depending
7), 8), 9), 10))
on ON/OFF
OFF
of X0
↓
Switched between the main and subsequence programs (1), 6), 12))
ON
When the CHG instruction is executed, END processing (e.g. timer timing, counter counting, WDT reset) is
Remarks
performed for the current program and operation is started from step 0 of the other program.
(2) When the A3N, A73, A3V and A3N board are used, the CHG instruction is only
executed on the leading edge of its input condition. Since M9050 is not
provided, execution contents of the CHG instruction are always same.
Input condition
X0
CHG instruction
execution in main
sequence program
Main sequence
program
Subsequence program
CHG instruction
execution in
subsequence program
(3) When the A3H, A3M, AnA, A3U, A4U and Q06H are used, the CHG instruction
is executed repeatedly while its input condition is on.
X0
CHG instruction execution
in main sequence program
Main sequence program
Subsequence program
CHG instruction execution
in subsequence program
Interlock
X000
CHG
1) 2) 3) 4) 5) 6) 7) 8) 9) 10) 11) 12)
Inter lock
X000
CHG
1) 2) 3) 4) 5) 6) 7) 8) 9) 10) 11) 12)
6 − 72
MELSEC-A