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5 Understanding Programming

5-50

CJ2 CPU Unit Software User’s Manual

Global symbols are symbols that are supported for all tasks in the target CPU Unit. For example, there-

fore, a symbol named “AAA” would be the same address in all tasks in the target CPU Unit.

Example: If the symbol named “AAA” is set as a global symbol, the same address will be assigned

(e.g., CIO 3.00) even if the task is different.

Local symbols can be accessed only from the task they are in defined. Each local symbol is supported

in only one task. Local symbols are specified separately for each task, so identical symbols will be han-

dled as different symbols for different tasks.

For example, if the symbol named “AAA” is set as a local symbol, different addresses (e.g., CIO 0.00

and CIO 3.00) can be allocated for different tasks with the same “AAA” symbol.

5-5-3 Global Symbols

5-5-4 Local Symbols

AAA

3.00

AAA

3.00

PLC

Task A

Task B

The same address will be

assigned (e.g., CIO 3.00)

even if the task is different.

Global symbol

AAA

0.00

AAA

3.00

PLC

Local symbol

for task A

Local symbol

for task B

Task A

Task B

Different addresses

(e.g., CIO 0.00 and

CIO 3.00) can be

allocated.

Omron CJ2 CPU UNIT SOFTWARE User Manual

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