When the execution result is 0, the system variable #L_CalcZero turns ON.
When checking the result using system variables, make sure the check takes place after the instruction has been executed. When checking the state after multiple instructions have been executed, system variables will store the result only of the last processed instruction.
Program Example
NOT
When the positive transition instruction turns ON, the NOT instruction will be executed. When the NOT instruction is executed, the result value obtained by logically inverting Data_A is stored in D1.
When using a normally open instruction, as long as the instruction variable is ON, the NOT instruction is always executed.
NOTP
When the normally open instruction turns ON, the NOTP instruction will be executed. When the NOTP instruction is executed, the result value obtained by logically inverting Data_A is stored in D1.
Even when using a normally open instruction, the NOTP instruction executes only when it detects the upward transition.
Therefore, the NOTP instruction is executed only for one scan, even when the normally open instruction bit remains ON.