Python scripts (script groups)

A Python Script worksheet, also called a Script Group, is used to implement program logic (using Python) that is executed during runtime.

To create a new Script worksheet:

Choose one of these options to create and open a new scripting worksheet for editing:

• On the ribbon Insert tab Task Worksheets group, select Script, then choose the type of sheet on the menu: VBScript or Python.

• In the Tasks tab of the Project Explorer, open the Script folder to access the VBScript and Python subfolders. Right-click the appropriate Script subfolder, VBScript or Python, and choose Insert on the context menu.

A new Script worksheet opens in the Screen/Worksheet Editor.

To edit and save a Script worksheet:

1. In the Tasks tab of the Project Explorer, open the Script folder to access the VBScript and Python subfolders. Open the appropriate Script subfolder, VBScript or Python, and either double-click the script or right-click it and choose Open on the context menu. The script worksheet is opened in the Screen/Worksheet Editor.

2. Enter your code in the interface. For example:

   temperature_fahrenheit = HMI.GetTagValue("Temp1_F")

   temperature_celsius = fahrenheit_to_celsius(temperature_fahrenheit)

   HMI.SetTagValue("Temp1_C", temperature_celsius)

3. Save your changes. If saving a new Script worksheet, you will be prompted for a Sheet Number.

   

   The displayed name of the new worksheet uses the Sheet number of the worksheet, for example 1, followed by a colon and then the string entered in the Description field, if any; for example Temperature Script.

   

   Note: When a Tasks script worksheet or a Global Procedures script worksheet is saved during runtime (on-line configuration), the Startup Script will be executed again and the values of the local variables of any script worksheet will be reset.

Script worksheet features and considerations

• The code configured in each script worksheet is executed by the Background Task module. The project scans the worksheets sequentially (based on the worksheet number).

• Only the scripts/script groups in which the condition configured in the Execution field of the worksheet is TRUE (non-zero) are executed.

  Note: The Execution field only supports syntax supported by the Built-in Scripting Language. Only the body of the worksheet supports another scripting language (Python or VBScript).

• The Description field accepts a string value. This value will appear in the name of script worksheet in the Project Explorer.

• Variables, classes, and procedures declared in the worksheet have local scope for that specific worksheet/group only, unless declared global. By default, they are not available for other worksheets or interfaces.

• You can define procedures in the script worksheet, and you can call procedures defined in the Python Global Procedures or in the Python Startup Script.

• You can put a password on any of your scripting worksheets to prevent them from being edited or analyzed by other users. See Password-protecting files for more information.