Shared Features: Expression Builder

The Expression Builder is a handy feature that will be used again and again while working with Vehicle Spy. This user friendly dialog builds expressions for many tasks such as controlling Function Blocks, linking signals to Graphical Panel elements, and creating custom filters. The interface is constant throughout Vehicle Spy, so there is no burden of learning dozens of complicated dialogs. Just get familiar with the Expression Builder and that's it! Please refer to Figure 1 below as the features of this dialog are explained further.

Enter Expression Area:

Enter an equation directly into the Expression field at the top of the screen (Figure 1:). This field has a right click menu with standard editing features. Use Evaluate as text (located below the Expression field) for expressions containing only text, or a combination of text and pure data elements without operations performed on them. For example, the expression "The value of engine rpm is {Engine RPM :in1}" should have evaluate as text enabled. If an expression value will be displayed, use the Custom Format options (Figure 1:) to control its format and units, and min/max values.

Expression Builder Area:

Vehicle Spy data sources are selected in the column on the far left. When a source is selected its data items will be displayed in tree form to its right (Figure 1:). When a data item is chosen its available properties are displayed just below the data item tree (Figure 1:). After you select an item and its property you can add it to the Expression field by clicking the Add to Expression button (Figure 1:). Create more complicated expressions using the Add Operator and Calculator Panel functions (Figure 1:) or by typing in the Expression field directly. After your equation is complete, it can be tested by clicking the Test button (Figure 1:). The test result will display below. When you are finished building your expression, click the Ok button (Figure 1:) to return to the previous view. Note that similar to C/C++ or Visual Basic, Boolean type equations are false when they evaluate to zero and true otherwise.

Data Sources, Data Items, Properties, & Operators: