Creating and handling Tasks

This article explains how to create and handle Tasks via TwinCAT Automation Interface. It consists of the following topics:

General information

There are two types of Tasks which can be configured in TwinCAT XAE and therefore also via Automation Interface: Tasks with Process Image and without. When you insert a new Task in TwinCAT XAE, you can decide whether you want to include a Process Image or not by selecting the corresponding checkbox in the "Insert Task" dialog.

Creating and handling Tasks 1:

As a result, the inserted Task either includes three more child nodes (Image, Inputs, Outputs) or not - as the following example shows (Task 1 = With Image, Task 2 = Without Image).

Creating and handling Tasks 2:

Inserting Tasks

To insert a Task via Automation Interface, you can make use of the ITcSmTreeItem::CreateChild() method and the corresponding SubTypes for "With Image" (SubType = 0) and "Without Image" (SubType = 1).

Code Snippet (C#) 

ITcSmTreeItem tasks = systemManager.LookupTreeItem("TIRT");
tasks.CreateChild("Task 1 (With Image)", 0, null, null);

Code Snippet (Powershell):

$tasks = $systemManager.LookupTreeItem("TIRT")
$tasks.CreateChild("Task 1 (With Image)", 0, $null, $null)

Code Snippet (C#) 

ITcSmTreeItem tasks = systemManager.LookupTreeItem("TIRT");
tasks.CreateChild("Task 2 (Without Image)", 1, null, null);

Code Snippet (Powershell):

$tasks = $systemManager.LookupTreeItem("TIRT")
$tasks.CreateChild("Task 1 (Without Image)", 1, $null, $null)

Inserting input/output variables

You can add Input/Output variables to process images (Task "With Image"), which can then be linked with I/O devices or variables from other Tasks. The corresponding dialog from TwinCAT XAE lets you choose e.g. the data type and address of the input/output variable in the process image. By clicking on "Ok", the variable will be added to the process image.

Creating and handling Tasks 3:

This procedure can also be triggered via Automation Interface by using the ITcSmTreeItem::CreateChild() method with the corresponding variable data type as vInfo. In this case the SubType specifies the "Start Address", as shown in the dialog above.

Code Snippet (C#):

ITcSmTreeItem task1 = systemManager.LookupTreeItem("TIRT^Task 1 (With Image)^Inputs");
task1.CreateChild("bInput", -1, null, "BOOL");

Code Snippet (Powershell):

$task1 = $systemManager.LookupTreeItem("TIRT^Task 1 (With Image)^Inputs")
$task1.CreateChild("bInput", -1, $null, "BOOL")

By using SubType = -1, TwinCAT automatically attaches the new variable at the end of the variable list.