Set Up Variables and Constants

Introducing the Variable Dictionary View

The Variable Dictionary is a store for all the variables, constants, and formulae in your session.

To view or edit the items in the Variable Dictionary, click the button, shown, in the Data Objects pane.

Selecting the Variable Dictionary view displays the variables, constants, and formulae in the current project.

Following is an example of the Variable Dictionary view.

The upper pane shows a list of all the current variables, constants, and formulas. The lower pane displays edit boxes so you can specify the settings of the selected variable, constant, or formula.

Different Variable Dictionary Items

• Variables — standard items that feed into models, strategies and tables, and define ranges for these items

• Constant — used for inputs that you do not want to change

• Formulae — used when you want a variable item to depend on another

Importing and Exporting a Variable Dictionary

A variable dictionary contains all the variable items for your calibrations. You can set up your variable dictionary once, and use it in many calibrations.

If you import a model, it has variables associated with it, in which case you might not have to import a variable dictionary.

Importing a Variable Dictionary

To import a dictionary of variables from an .xml file,

1. Select File > Import > Variable Dictionary.

2. Select the correct dictionary file.

Exporting a Variable Dictionary

After setting up a variable dictionary, you can save the dictionary for use in many different calibrations.

To export a dictionary of variables to an .xml file,

1. Select File > Export > Variable Dictionary.

2. Select a suitable name for the dictionary file.

Using the Variable Menu

The Variable menu in the variable dictionary enables you to alter variable items. These choices are also available in the right-click context menu on the list view.

Change item to:

• Alias

  Changes the selected item to be an alias of another item in the current project. For example, if you have two variables, engine_speed and n, you can change n to be an alias of engine_speed, with its maximum and minimum values.

• Formula

  Changes a variable or constant into a formula. You have to define the right side of the formula, and you can select the check box to calculate the range.

• Constant

  Changes a variable or formula into a constant. The value of the constant is the set point of the old item.

• Variable

  Changes a constant or formula into a variable. The range is from 0 to twice the constant's value (negative values have a maximum of 0).

Using Aliases

The variable dictionary enables you to use the same set of variables, constants, and formulas with many different models and calibrations.

Why Use Aliases?

It is possible that in one model or strategy the engine speed has been defined as N, and in another it has been defined as rpm. The alias function enables you to automatically link inputs with various names to a single CAGE variable when you import models and strategies.

Creating an Alias

For example, in a variable dictionary there are two variables:

• N, with a range of 500 to 6500

• rpm, with a range of 2500 to 3500

To set rpm to be an alias of N,

1. Highlight the variable rpm.

2. Select Variable > Change item to > Alias.

3. In the dialog box, choose N from the list.

This eliminates the variable rpm from your variable dictionary, and every model and calibration that refers to rpm now refers to N instead.

Note

If N is made an alias of rpm in the preceding example, the range of N is restricted to the range of rpm, 2500 to 3500.

You can also add aliases to existing items by entering a list of names in the Alias edit box.