Configure Timed Sequence Dialog Box

LabVIEW 2018 Help


Edition Date: March 2018
Part Number: 371361R-01
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Requires: Base Development System (Windows)

Double-click the Input node on a Timed Sequence structure or right-click the node and select Configure Input Node from the shortcut menu to display this dialog box.

Use this dialog box to configure a timing source, priority, and other advanced options for the execution of a Timed Sequence structure.

Use the Configure Next Frame Timing dialog box to configure options for the next frame of the structure.

This dialog box includes the following components:

  • Sequence Timing Source / Trigger—Specifies the type and name of the timing source for the Timed Sequence structure. The Sequence Timing Source / Trigger settings include the following components:
    • Select an Internal Timing Source—Specifies an internal timing source from the Source Type listbox to control the timed structure.
      • Source Type—Specifies an internal timing source to control the timed structure. In addition to the internal timing sources, this listbox includes any timing sources you configured on the system.
        • 1 kHz Clock—Selects the 1 kHz clock of the operating system. Using the 1 kHz clock, a timed structure can execute an iteration once every 1 millisecond. All LabVIEW platforms that can run a timed structure support the 1 kHz timing source.
        • 1 MHz Clock—Selects the 1 MHz clock supported on RT targets with Intel Pentium III or later-class processors. Using the 1 MHz clock, a timed structure can execute an iteration once every 1 microsecond.
          Note  You must have the LabVIEW Real-Time Module installed and must have created a VI under the RT target in the Project Explorer window to use this option.
        • 1 kHz <absolute time>—Selects the 1 kHz clock of the operating system. When you select this timing source, the timed structure uses timestamps for all input and output terminals related to start and finish times. You can use an absolute timing source to specify a specific date and time to start execution.
        • 1 MHz <absolute time>—Selects the 1 MHz clock supported on RT targets with Intel Pentium III or later-class processors. When you select this timing source, the timed structure uses timestamps for all input and output terminals related to start and finish times. You can use an absolute timing source to specify a specific date and time to start execution.
        • Synchronize to Scan Engine—Synchronizes the timed structure to the NI Scan Engine. Using this timing source, the timed structure executes at the end of each scan. The period between iterations corresponds to the Scan Period setting you configure on the Scan Engine page. This option is only available on targets that support the NI Scan Engine.
        • 1 kHz <reset at structure start>—Selects the 1 kHz timing source that resets on the first call of every invocation of the structure.
        • 1 MHz <reset at structure start>—Selects the 1 MHz timing source that resets on the first call of every invocation of the structure.
      • Source name—Specifies the name for the instance of the timing source. For example, if you enter the same name for Source name in two different timed structures, both structures share the same instance of the clock as their timing source.
        Note  Using the same timing source ensures that the phase of the structures is the same, but the structures might not start at the same time. You can synchronize the start of timed structures using the Synchronize Timed Structure Starts VI.
  • Frame Timing Source—Specifies the options for the timing source of the frames.
    • Use timing source of sequence—Specifies the timing source of the structure as the timing source for the frames.
    • Use built-in source from below—Specifies a separate internal timing source for the frames.
      • 1 kHz <reset at structure start>—Selects the 1 kHz timing source that resets on the first call of every invocation of the structure.
      • 1 MHz <reset at structure start>—Selects the 1 MHz timing source that resets on the first call of every invocation of the structure.
  • Sequence Timing Attributes—Specifies the priority and other advanced options for the structure. The Sequence Timing Attributes settings include the following components:
    • Priority—Specifies the priority of the execution of the timed structure relative to other structures that are ready to execute. The higher the number you enter, the higher the priority of the timed structure over other structures. The value for the Priority must be a positive integer between 1 and 65,535.
      Note  These priorities are different from VI priorities. LabVIEW executes the timed structures at a priority level below the time-critical priority and above the high priority. The LabVIEW execution system is preemptive, so a higher priority timed structure that is ready to execute preempts all lower priority structures also ready to execute and other LabVIEW code not running at time-critical priority.
    • Advanced Timing—Specifies advanced timing options. The Advanced Timing settings include the following components:
      • Deadline—Specifies a time boundary for the completion of the first frame of the Timed Sequence structure. If the first frame does not complete before the deadline value, the Finished Late? [f-1] output on the Left Data node of the next frame returns TRUE.
      • Timeout (ms)—Specifies the maximum amount of time, in milliseconds, the first frame of a Timed Sequence structure can wait for a trigger event from the timing source before it passes Timeout in the Wakeup Reason output on the Left Data node in the next frame.
      • Offset / Phase—Specifies the starting time or phase for the first frame of the structure. You can use this option to align the phases of structures. For example, you can configure two Timed Sequence structures to use the same timing source instance by specifying the same name in Source name. You can enter a value of 0 in Offset / Phase for the first Timed Sequence structure and enter a value of 100 in Offset / Phase for the second Timed Sequence structure. The Timed Loops execute at their respective periods, but 100 timing units separate their execution.
      • Structure Name—Uniquely identifies the Timed Sequence structure.
        Note  When you specify a name for a Timed Sequence structure that you want to use in a reentrant VI, you must wire a string control to the Sequence name item on the Input node, and make the string control an input terminal on the connector pane of the reentrant VI.
    • Processor Assignment—Specifies the processor assigned to handle execution. The Processor Assignment settings include the following components.
      • Mode—Specifies how to assign available processors to handle execution. You can select from the following options:
        • Automatic—LabVIEW assigns a processor to handle execution automatically. LabVIEW disables the Processor control and sets it to -2 when you select this option.
        • Manual—The value you enter in the Processor control specifies the processor you want to use to handle execution. You must specify a value between 0 and 255 in the Processor control.
      • Processor—Specifies the processor you want to handle execution. The default is -2, which means LabVIEW automatically assigns a processor. To manually assign a processor, enter a number between 0 and 255, where 0 represents the first processor. If you enter a number that exceeds the number of available processors, you generate a run-time error and the timed structure does not execute.

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