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MELSEC-Q/QnA
3 CONFIGURATION OF INSTRUCTIONS
3.7 Conditions for Execution of Instructions
The following four types of execution conditions exist for the execution of CPU module sequence
instructions, basic instructions, and application instructions:
• Non-conditional execution...................Instructions executed without regard to the ON/OFF status
of the device
Example: LD X0, OUT Y10
• Executed at ON...................................Instructions executed while input condition is ON
Example: MOV instruction, FROM instruction
• Executed at leading edge ...................Instructions executed only at the leading edge of the input
condition (when it goes from OFF to ON)
Example: PLS instruction, MOVP instruction
• Executed at trailing edge ....................Instructions executed only at the trailing edge of the input
condition (when it goes from ON to OFF)
Example: PLF instruction
For coil or equivalent basic instructions or application instructions, where the same instruction can
be designated for either execution at ON or leading edge execution, a "P" is added after the
instruction name to specify the condition for execution.
• Instruction to be executed at ON Instruction name
• Instruction to be executed at leading edge Instruction name + P
Execution at ON and execution at leading edge for the MOV instruction are designated as follow:
MOVP K4X0 D0
Execution at leading edge
MOV K4X0 D0
Execution at ON
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