Precautions During Programming FP08 − 168.5 Instruction of Leading Edge Detection Method8.5.3 Precautions When Using a Control InstructionInstructions which leading edge detection compare the condition of the previousexecution and the condition of the current execution, and execute the instruction onlyif the previous condition was off and the current condition is on. In any other case, theinstruction is not executed.When a leading edge detection instruction is used with an instruction which changesthe order of instruction execution such as MC, MCE, JP or LBL, the operation of theinstruction may change as follows depending on input timing. Take care regarding thispoint.Example 1:Using the DF instruction between MC and MCE instructionsX1DFY0MCE 0X0MC 0Previousexecution of DFinstructionPreviousexecution of DFinstructionTime chart 2Time chart 1X0X1Y0The input condition (X1) for the DF instruction hasnot changed since the time of the previousexecution, thus derivative output is not obtained.X0X1Y0The input condition (X1) for the DF instruction haschanged from off to on since the time of the previousexecution, thus derivative output is obtained.
