Configure Formula Parameters

Formula parameters represent all the configurable information that a phase needs to run properly. Formula parameters are placeholders for values. Values are assigned in the Recipe Editor when the phases are used in a recipe procedure. Values are used by the AVEVA Batch Management System in specific ways when recipes are processed.

Formula parameter configurations consist of the following information:

• Name (required, 16 characters maximum)

• Description (optional, 120 characters maximum).

• Type (required, input, output, or process variable)

  Process and transfer phases can have any number of input, output, or process variable formula parameters.

• UOM (optional, process variables only)

• Data Class (required: analog, discrete, string, or enumeration)

  Each formula parameter must be assigned a data class type. This assigned data class determines what data class of tags are available for assigning to the elements of each parameter type. For example, only analog tags can be assigned to the elements of an analog parameter. Process variable parameters can be defined as either analog, discrete, string, or enumeration. Input and output parameters are defined as analog and cannot be changed.

  Note: Use the Data Class control to change the data class of a process variable. If you change the data class by accident and answer No to the dialog box prompt, the control may not reset to the true data class. In this situation, reselect the correct data class.

• Parameter Elements (optional)

  Each type of formula parameter has associated elements as shown in this table.

You can assign each parameter element to a tag. Tags are created and assigned, either automatically or manually.

Each element can be further configured for operator interaction:

• The Enable Display check box specifies whether or not the element is to be shown to an operator.

• The Edit Allowed check box specifies whether or not an operator is allowed to modify the element at run time.

• The Edit Required check box specifies whether the operator is required to modify the element at run time. However, the Edit Required option applies only to the end of the phase.

  An Acknowledge on Entry setting used in conjunction with an Edit Allowed target element can be used to effectively represent an edit that is required prior to the start of the phase.

• Element Default Values (optional)

  You can define default values only for process variable formula parameter elements. The default value is set to zero if it is not explicitly defined. These values are used by the AVEVA Batch Management System unless they are changed in the recipe.

  The High Limit and Low Limit default values are used by the Recipe Editor to prevent the user from entering an out of range value. When an out of range value is entered into a recipe, an error message appears and the Recipe Editor clamps the value to the default limit.