Mitsubishi Electric MELSEC Q Series Programming Manual page 30

Precautions
The following example shows that the operation results an undefined value.
When Variable_1 is OFF, the MOV or SET instruction is executed though the ADD_E or TEST instruction is not executed.
Even though Variable_1 is OFF, a value may be set in D2 by the MOV instruction or M1 may turn ON by the SET instruction.
Input ENO of the first instruction to EN of the next instruction not to perform the sequential operation when EN is OFF.
4 PROGRAM CONFIGURATION
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4.2 POUs