Scheduled tasks

7 min readScheduled tasks

Defining tasks that run a script at a certain interval, time or day, or when a tag condition is met; running in Live, catching up on missed tasks and the status window.

A scheduled task runs a script for you: for example performing a calculation every second, resetting a counter at the start of a shift, or writing a warning when a tag exceeds a certain value. The task definition does not run the script; it determines when the script runs, and the script does the work. Tasks are in the Scheduled tasks section.

Defining tasks

Prepare the script
In the Scripts section, write the script the task will run (VBS module or action, C, JavaScript function or Python). For details, see Script editor.
Add the task
In the Scheduled tasks section, click Add and enter a Name.
Select the trigger
Select from the Trigger list; the relevant fields appear (table below).
Connect the script
Select the script from the Script to run list. For a VBS module, a C script and a Python script, the procedure / function to call is selected in the Procedure / function column; if it is empty, the procedure or function with the same name as the script is called.
Check
F7 lists a missing script, time, tag, date, or day selection as an error or warning.

Scheduled tasks: the table and the properties panel below it. The Schedule card of the selected task shows the day selection and the next run times.

Triggers

Trigger	When it runs	Fields
Cyclic	Each time the duration of the selected cycle elapses (at most every 100 ms).	Cycle.
Every day at a specific time	Every day at that time.	Time (`SS:DD`, example `07:30`).
On specific days of the week	At that time on the selected days.	Time; Monday … Sunday switches on the Schedule card. Default: weekdays.
On a specific day of the month	Every month on that day and at that time. If the month does not have that day (example 31), it runs on the last day of the month.	Time; Day of the month (1 – 31) or the Last day of the month switch.
On a specific day of the year	Every year in that month, on that day and at that time. A task set for 29 February runs on 28 February in a non-leap year.	Time; Month, Day of the month.
One-time (date and time)	Once; after it runs, it becomes completed and does not run again.	Time; Date. If the date or time changes, the completed flag is reset.
On tag change	Each time the value of the selected tag changes; the new value of the tag is passed to the script as the first parameter (in a VBS module, a Bool value as binary).	Tag.
Tag condition (threshold / edge)	Once when the condition starts to be met; it runs again when the condition is lost and then met again. It does not run if the condition is already met when Live starts.	Tag; on the Tag condition card: Condition (Rising edge, Falling edge, When the value changes or a comparison of the value with the threshold >, ≥, <, ≤, =, ≠), Threshold, On every change while met.
When Live starts	Once, when the project is opened.	—
When Live closes	Once when Live closes; shutdown waits for the task to finish.	—

For time triggers, the time and date are those of the local calendar of the Live computer. The Schedule card of the selected task lists the next five run times; for a task with no day selected or whose time has passed, a “will not run” warning appears.

Operation in Live

Time triggers are checked every few seconds; the task starts at most about 5 s after the scheduled time.
A time that does not exist during the daylight saving time change (for example 02:30) runs once at the moment of the change; a repeated time runs only the first time it occurs. If the clock is set back, the schedules are recalculated, but the same scheduled minute does not run twice.
If the same script is triggered again while its previous call is still running, this call is skipped (state Skipped).
Each task run is written to the event log with the type gorev; the state (last run, result, number of runs and errors) is stored in the file <Proje>.veri\depo\gorev_durum.json and is retained when Live is opened again.
If Scheduled tasks is switched off in the Startup sequence, no task (timer, tag, startup) runs.

Missed tasks

If a scheduled time passes while Live is closed or the computer is asleep, the task cannot run at that moment. For tasks with a time trigger, if Run at startup if missed is on, the task is run once when Live opens (it does not run separately for each missed time); if it is off, the missed time is skipped and “missed” is written to the event log. A run triggered at most 2 minutes after the scheduled time is not considered late and runs normally. Past times are not made up for a newly added task; when the definition of a task (day, time, date …) changes, its completed and catch-up state is reset. The time Live was closed is determined from the saved “last alive time” (written about once a minute).

Task status window

In Live, System menu › Tasks… (or the Open the task status window function in the menu bar) shows the state of all tasks: Task (with the script name), Trigger, Last run and its source (Scheduled, Catch-up, Tag change, Tag condition, Cycle, Startup, Shutdown), Result (OK, Error and its message, Skipped, Completed, Running, Inactive, Not run yet; the last missed time and how many were missed), the scheduled time under Next and Number. The window refreshes every second.

Scheduled tasks window in Live: last run, result and next scheduled time.

If a script produces an error, the result of the task is Error and the message contains the script, the procedure and the line (for VBS and C scripts; the exception message for JavaScript). An error does not stop the later runs of the task.

Limitations and points to note

The task does not run if Script to run is not selected or Enabled is off (Problems warns about a task without a script).
There is no print task (scheduled report printing); silent printing is not supported. To save a scheduled report, a task can set a tag and use the report's trigger tag (Designing reports).
In browser monitoring (read-only), tasks do not run; tasks run only on the main Live PC.