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
OR
When the positive transition instruction start turns ON, the OR instruction will be executed. When the OR instruction is executed, the result value obtained by ORing Data_A with FOFF is stored in D1.
When using a normally open instruction, as long as the instruction variable is ON, an OR instruction is always executed.
ORP
When the normally open instruction turns ON, the ORP instruction will be executed. When the OPR instruction is executed, the result value obtained by ORing Data_A with F0FF is stored in D1.
Even when using a normally open instruction, the ORP instruction executes only when it detects the upward transition.
Therefore, even when the variable of the NO instruction is always ON, the ORP instruction is executed only for one scan.