Adding subflowcharts

If you add a subflowchart, it is essentially used as a step. This make it easier to reuse a flowchart structure across multiple projects. For example, you can have a subflowchart that handles communications with a PLC, which is often developed by someone other than the vision specialist. You can then add this subflowchart as a separate step to your main flowchart or to another subflowchart.

By adding subflowcharts, you can also simplify and organize more complex projects. Such projects should typically have one main, simple flowchart, that includes a series of subflowchart steps.

To add a subflowchart, access the Flowcharts page of the Add Step dialog.

For a new subflowchart, enter a unique name, click the New Flowchart button, add a description, and click Add. Your project can now access the new subflowchart. By default, the subflowchart is added to the current (calling) flowchart. The subflowchart appears as a step, with double sidelines.

Configuring a subflowchart

To configure a subflowchart, you must access it by double-clicking on the subflowchart step, or by selecting the subflowchart name with either the Flowchart menu item or by right-clicking inside the Flowchart view. A newly created subflowchart includes only the Start and End circle elements.

You can configure a subflowchart as you would a regular flowchart. For example, you can add new steps or copy steps from other flowcharts. To return to the calling flowchart, or to access any other flowchart in your project, use the Flowchart menu or right-click inside the Flowchart view.

A subflowchart's inputs (parameters) and outputs

A subflowchart can have as many inputs (also referred to as parameters) and outputs as you require. At design-time, the Quick Evaluate pane displays the value of all inputs, outputs, and variables of all the flowcharts and subflowcharts in a project.

If you add a variable inside a subflowchart, set its Reset Point property to specify when the variable should be reset to its initial value. For more information, see the Lifetime section in Chapter 25: Variables and the Store step.

Inputs

Inputs are the values the subflowchart receives from the calling flowchart. Click on the Start circle element to define the inputs to receive. Use a meaningful name and description for each input, particularly if you plan to add the flowchart to the library for future use. For more information, see the Managing subflowcharts section later in this chapter.

Input expressions must have a unique name and be of type number, boolean (True or False), string, or image. When you add an input expression, a default is set: 0 for Numeric, False for Boolean, null for Image, or an empty String. Once added, you cannot change the type.

In the calling flowchart, set appropriate values for all the subflowchart's inputs if the default input expressions are not suitable. Often, the input expressions are links to the results of other steps.

Outputs

Outputs are the values the subflowchart sends to the calling flowchart. Click on the End circle element to define the outputs to send. Like a subflowchart's inputs, outputs must be of type Numeric, Boolean, String, or Image.

Linking to other flowcharts

When configuring steps inside a subflowchart, a dropdown list giving access to images and fixtures will only show images and fixtures of the current subflowchart. To link to anything in another flowchart, use the Link editor.