6. BASIC INSTRUCTIONS
6
−
73
MELSEC-A
Execution of PLS Instruction Used with CHG Instruction
(1) When the A3 is used, execution contents of the PLS instruction change with
status of M9050 when other input conditions are same.
Status of M9050
OFF ON
Ladder example
The following program is written at step 0 of the main and subsequence programs.
Timing chart
OFF
M0 is not switched on.
M0 is not switched on.
ON
M0 is only switched on during the first scan after
switched by the CHG instruction.
M0 is only switched on during the first scan of the
subsequence program selected by the CHG
instruction executed after X0 is switched on.
Oper
at
ion
X0
status
OFF
↓
ON
M0 is only switched on during 1 scan.
M0 is only switched on during 1 scan.
(2) When the A3N, A73 and A3V are used, execution contents are always same.
Ladder example
The following program is written at step 0 of the main and subsequence programs.
Timing chart
OFF
M0 is not switched on.
ON
M0 is only switched on during the first scan of the subsequence program selected by the CHG instruction
executed after X0 is switched on.
Oper
at
ion
X0
status
OFF
↓
ON
M0 is only switched on during 1 scan.
X000
PLS M0
Input condition
Main sequence
program run
Subsequence
program run
X0
M0
CHG instruction execution
CHG instruction execution
1 scan
Main sequence
program run
Subsequence
program run
X0
M0
CHG instruction execution
CHG instruction execution
1scan
CHG instruction execution
Main sequence
program run
Subsequence
program run
X0
M0
1 scan
CHG instruction execution
X000
PLS M0
Input condition
0
0
Summary of Contents for MELSEC-A series
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