System Functions And Scripts - Siemens SIMATIC TP 270 Operating Instructions Manual

Runtime functionalities of a project

8.6 System functions and scripts

8.6 System functions and scripts
Application
System functions and scripts are used in Runtime for the following purposes:
• To control the process
• To utilize the properties of the HMI device
• To make system settings on the HMI device online
In WinCC flexible, each system function and each script s linked to an object, such as a
button, field or screen, and an event. An event immediately triggers the system function.
System functions
System functions are predefined functions that are used to implement many tasks in
Runtime. For example:
• Calculations, e.g. increase of a tag value by a specific or variable amount
• Logging function, such as starting a process value log
• Settings, such as changing the PLC or setting a bit in the PLC
• Alarms, for instance after logon of a different user
Scripts
Scripts may also be included in the project for specific applications which may require
additional functions. For the creation of scripts, WinCC flexible provides an interface to
Microsoft Visual Basic Script (VBScript). This allows you to integrate additional functions
such as:
• Conversion of values, e.g. between different physical units (temperatures)
• Automation of production sequences
Events
The object and the selected function determine what events can be defined as triggers for
executing a system function.
For example, the events "Change value", "BelowLowerLimit" and "AboveUpperLimit" belong
to the "Tag" object. The "Loaded" and "Cleared" events belong to the "Screen" object.
8-6
A script can control a production sequence by transferring production data to a PLC. The
status can be checked based on the returned values, and appropriate measures can thus
be initiated.
TP 270, OP 270, MP 270B (WinCC flexible)
Operating Instructions, Edition 03/2004, 6AV6691-1DD01-0AB0