Rockwell-automation Logix5000 Controllers I/O and Tag Data Programming Instrukcja Użytkownika Pobierz pdf (Strona 58)

Chapter 3 Force I/O

Use an I/O force to override:

• An input value from another controller (that is, a consumed tag).

• An input value from an input device.

• Your logic and specify an output value for another controller (that is, a

produced tag).

• Your logic and specify the state of an output device.

Important:

•

Forcing increases logic execution time. The more values you force, the longer it takes to execute the

logic.

• I/O forces are held by the controller and not by the programming workstation. Forces remain even if the

programming workstation is disconnected.

Use these guidelines when forcing an I/O value.

• You can force all I/O data, except for configuration data.

• If the tag is an array or structure, such as an I/O tag, you can force a BOOL,

SINT, INT, DINT, or REAL element or member.

• If the data value is a SINT, INT, or DINT, you can force the entire value or

you can force individual bits within the value. Individual bits can have a

force status of:

• No force

• Force on

• Force off

• You can also force an alias to an I/O structure member, produced tag, or

consumed tag.

• An alias tag shares the same data value as its base tag, so forcing an alias

tag also forces the associated base tag.

• Removing a force from an alias tag removes the force from the

associated base tag.

• If a produced tag is also Constant, you cannot use forces.

• If a produced tag is forced, you cannot make it Constant.

When to use I/O force

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Rockwell-automation Logix5000 Controllers I/O and Tag Data Programming Instrukcja Użytkownika Strona 58