Rockwell-automation Logix5000 Controllers I/O and Tag Data Programming Manual do Utilizador descarregar pdf (Página 26)

Chapter 2 Organize tags

• Routines cannot access data that is at the local scope (local tag) of

another program.

• You can reuse the tag name of a local tag in multiple programs.

• For example, both Program_A and Program_B can have a local tag

named Tag_4.

• You can also use program parameters to share data between programs as

an alternative to controller-scope tags. See Program parameter scope

page 27.

Avoid using the same name for both a controller tag and a local tag. Within a

program, you cannot reference a controller tag if a local tag of the same name exists

for that program.

Certain tags must be controller scope (controller tags).

If you want to use the tag Then assign this scope

In more than one program in the project Controller scope (controller tags)

In a Message (MSG) instruction

To produce or consume data

In any of the seven AXIS data types

To communicate with a PanelView terminal

None of the above Program scope (local tags)

26 Rockwell Automation Publication 1756-PM004E-EN-P - October 2014

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Rockwell-automation Logix5000 Controllers I/O and Tag Data Programming Manual do Utilizador Página 26