Ensuring Proper OnShow Script Execution

When an OnShow script includes external references to tags, it is possible that the data from these tags is not yet available when the OnShow script runs. As a result, the script might not work properly.

To avoid this situation, you can enter a value in the Data Timeout field. For the duration of the data time-out period, the system checks for the presence of the external reference data. After all external reference data is present, the system executes the OnShow script.

If the data time-out period expires before all external data is present, the OnShow script is executed. However, the script might not work properly.

The default value in the Data Timeout field is:

• For new Industrial Graphics, 1,000 ms.

• For some HMI symbols, 0 ms; that is, the presence of external reference data is not checked. Verify the behavior of your HMI/SCADA software.

The maximum data time-out value is 30,000 ms.

Note the following issues regarding OnShow scripts and the Data Timeout function:

• The Data Timeout function is not available for the other trigger script types. It would be rare for external reference data to not be available in time for those scripts.

• The execution of the OnShow script is not delayed if there is an invalid reference (that is, the reference's quality is Bad).

• Named scripts are blocked until the OnShow script has completed, so some could be missed. For example, the named script OnDataChange might not run for the first few updates.

• Delayed OnShow scripts within nested embedded graphics might run out of order for the different nested levels. If the outer-most level is delayed but the inner levels are not delayed and are executed immediately, the order of execution will be changed.

Related Topics

Configuring the Predefined Scripts of a Graphic