When To Use I/O Force - Allen-Bradley 1756-L61 ControlLogix 5561 Programming Manual

Chapter 3 Force I/O

When to Use I/O Force

60
where:
Force_Status is a DINT tag.
To determine if
Forces are installed
No forces are installed
Forces are enabled
Forces are disabled
Use an I/O force to:
override an input value from another controller (that is, a
consumed tag).
override an input value from an input device.
override your logic and specify an output value for another controller (that
is, a produced tag).
override your logic and specify the state of an output device.
IMPORTANT
IMPORTANT
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, 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.
Rockwell Automation Publication 1756-PM004D-EN-P - September 2012
Examine this bit
0
0
1
1
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.
For this value
1
0
1
0