Syntax for SFC Step Actions

For SFC step actions, the type of action determines the valid expressions. The three action types—Boolean, non-Boolean, and Assignment—have the following impacts on expressions:

• Assignment – Assigns the result of an expression to a destination. For example, the following action text sets a parameter to 1:

  '//XV-101/DC1/SP_D':=1;

• Boolean – Sets a destination to TRUE. This destination must be a module-level Boolean parameter of the module you are working on. The action text for this type of action is the Boolean parameter, and the action qualifier defines the action (when to set this parameter to TRUE). For example, if you want to set a Boolean parameter to TRUE for the module called MPARAMETER, enter the following action text:

  MPARAMETER

• Non-Boolean – Executes a specific block. This block can be either a composite block or a function block, but it must be in the module you are working on. Action Text for this type of action is the function block name. The action qualifier defines the action (when to execute this block). For example, to execute a PID block called PID1, enter the following action text:

  PID1

  Tip

  To add a block to an SFC, select the Hierarchy View. Right-click, and then select Add. Select the type of block to add, and answer the questions.

  In the Function Block View of the module, blocks that are referenced by non-Boolean actions have the icon  in their lower left corner to indicate that the block runs only on demand. 

  Note

    Blocks that are not referenced by a non-Boolean action run continuously in the controller.