Mitsubishi Electric MELSEC iQ-R Series Programming Manual page 47

Precautions
■ When an interrupt program is used
When a label or device is specified for the array index, the operation is performed with a combination of multiple instructions.
For this reason, if an interrupt occurs during operation of the label defined as an array, data inconsistency may occur
producing an unintended operation result.
To prevent data inconsistency, create a program using the DI/EI instructions that disables/enables interrupt programs as
shown below.
DI
Program of the label defined as an array
4
EI
For the DI/EI instructions, refer to the following.
 MELSEC iQ-R Programming Manual (Instructions, Standard Functions/Function Blocks)
■ Array elements
When accessing the element defined in an array, access it within the range of the number of elements.
If a constant out of the range defined for the array index is specified, a compile error will occur.
If the array index is specified with data other than a constant, a compile error will not occur. The processing will be performed
by accessing another label area or latch label area.
4 LABELS
45
4.4 Arrays