Triggers

In the step program, triggers cause the step or jump condition of the active step to be met and the step program processing to continue. Triggers are linked to Aliases that reference object attributes.

Note: Triggers are usually linked to Boolean attributes, but can also use any other numeric data type (integer, float, double). The trigger value is coerced to True or False.

In the simplest While True case, when a Trigger (Boolean attribute) is true, the condition the Condition evaluates to true, the On Exit Output are written and the step is ready to transition the next scan. The Aliases panel maps attributes to Aliases. The Aliases are mapped to steps via values to be written at that step.

Step and Jump Conditions are triggered by referenced Boolean attributes in different ways, such as when the Boolean attribute:

• is true: While True

• becomes true while the step is active: On True

• is false: While False

• becomes false while the step is active: On False

• changes from true to false or vice-versa: Data Change

A condition can also be

• never fulfilled: Always False

• always fulfilled: Always True

without using any Aliases.