Before you start scheduling entries, you should understand how the Scheduler executes scripts. The Scheduler can run as a foreground or background task. When you run a schedule in the foreground, it runs on the same thread as the scripts in DeltaV Operate, allowing you to quickly test and debug scripts in the run-time environment. When you run a schedule in the background, it runs on a separate thread from the scripts in DeltaV Operate and therefore is not competing with the other scripts that may also be running.
Database information for each data source in a schedule is saved as part of the file on disk. When a schedule executes in the run-time environment, and the database information is not up-to-date, DeltaV Operate queries the database and resolvesthe tag definitions. This can be a time-consuming process the first time the schedule loads, which can slow the execution of the schedule.
Resolving schedules removes the need for DeltaV Operate to query the database. Therefore, resolved schedules execute faster in the run-time environment. We recommend resolving your schedules as a final step in the configuration process. The Resolve feature is available for both schedules and pictures.
If the process database is modified after you resolve a schedule, you need to run Resolve again.
To resolve a schedule:
Click the Resolve Files button on the Utilities Toolbar.
In the File Types area, select the Schedule check box.
In the Directories area, verify that your schedule directory is correct. If it is not, enter the correct path in the Schedules field.
In the Resolve Files area, select the schedule file you want to resolve. To select every file in the list, click Select All.
Click the Update Schedule Files button and click OK.
Run schedules that do not pop up forms in the background. When forms or message boxes pop up, that schedule's VBA queue is paused until the form is closed or the message box is acknowledged.
If you are using command wrappers in schedules that run as a background task, you can specify an Error Option as an additional, optional parameter. By including an Error Option, you can prevent a message box from appearing and delaying the complete processing of your script.
By using 2 as your Error Option parameter, you can send errors to Alarm History. By using 1 as your Error Option parameter, you can handle the error within your timer or event script. From there, for example, you can send it to the Windows Event Log.
If you want to run a timer or an event, you can put it directly into a picture. From a performance standpoint, it is not necessary to put one timer or event object into a schedule if it is only used when a particular picture is open. Simply put the timer or event object into that picture.