Configuring Timed Sequence Structures (Real-Time, Windows)

LabVIEW 2018 Help


Edition Date: March 2018
Part Number: 371361R-01
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To configure the initial execution options of a Timed Sequence structure and to specify options for the first subdiagram, or frame, of the sequence, use the Configure Timed Sequence dialog box. Double-click the Input node or right-click the Input node and select Configure Input Node from the shortcut menu to display the Configure Timed Sequence dialog box. You can use this dialog box to specify a timing source, set the priority, and to configure advanced options for the Timed Sequence structure.

You also can wire values into the input terminals of the Input node to configure the options of a Timed Sequence structure. By default, the Input node of the Timed Sequence structure does not display all of the available input terminals. You can resize the Input node or right-click the Node and use the shortcut menu to display hidden terminals.

Tips and Tricks for Using Timed Sequence Structures

The following list provides additional information about using a Timed Sequence structure.

  • Right-click the Timed Sequence structure border to add, delete, and merge frames. Unlike in a Flat Sequence structure, every frame of a Timed Sequence structure must have all of its inputs before the structure can execute.
  • The Right Data node of the last frame of a Timed Sequence structure does not include configuration options because you do not have to configure another frame or iteration.
  • A Timed Sequence structure executes in the data flow of a block diagram ahead of any VI not configured to run at a time-critical priority. You can change the priority of a Timed Sequence structure to change the order in which it executes relative to other timed structures on the block diagram.
  • To avoid unexpected timing behavior, do not add a VI configured to run at time-critical priority and a Timed Sequence structure to the same block diagram.
  • If you want each frame of the Timed Sequence structure to execute more than once, you can right-click the Timed Sequence structure border and select Replace with Timed Loop.

Configuring the Next Frame

Double-click the Right Data node of the current frame or right-click the node and select Configure Input Node from the shortcut menu to display the Configure Next Frame Timing dialog box. You can use this dialog box to specify a start time, a priority, a deadline, and a timeout for the next frame.

The start time specifies the time the next frame starts executing. Specify a start time value relative to the start of the current frame in units of the frame timing source. Enter a value in the Start text box of the Configure Next Frame Timing dialog box to specify a start time. The next frame returns TRUE in the Finished Late? output of the Left Data node if the frame does not start before the specified start time.

You also can use the input terminals of the Right Data node of a frame to configure the next frame or iteration of a Timed Loop dynamically. By default, the Right Data node of a Timed Sequence structure frame does not display all of the available output terminals. You can resize the Right Data node or right-click the Node and use the shortcut menu to display hidden terminals.



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