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Glossary
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task A scheduling mechanism for executing a program.
• By default, each new project file contains a pre-configured continuous
task.
• You configure additional, periodic tasks, as needed.
• A task provides scheduling and priority information for a set of one or
more programs that execute based on specific criteria.
• Once a task is triggered (activated), all the programs assigned
(scheduled) to the task execute in the order in which they are displayed
in the controller organizer.
• You can only assign a program to one task at a time.
See continuous task, periodic task.
timestamp A ControlLogix process that records a change in input data with a relative time
reference of when that change occurred.
transition In a sequential function chart (SFC), a transition is the true or false condition
or conditions that determine when to go to the next step.
U
uncached connection With the MSG instruction, an uncached connection instructs the controller to
close the connection upon completion of the mSG instruction. Clearing the
connection leaves it available for other controller uses. See connection,
cached connection.
unidirectional connection A connection in which data flows in only one direction: from the originator to
the receiver. See connection, bidirectional connection.
upload The process of transferring the contents of the controller into a project file on
the workstation.
If you do not have the project file for a controller, you can upload from the
controller and create a project file. However, not everything that is stored in a
project file is available from the controller. If you upload from a controller, the
new project file will not contain:
• rung comments
• descriptions for tags, tasks, programs, routines, modules, or user-defined
structures
• chains of aliases (aliases pointing to other aliases)
Alias chains are not completely reconstructed from the controller. If
there are several possible names for a data item, the firmware and
software choose a best-fit alias that may not reflect how the alias was
specified in the original project.
See download.
Publication 1756-PM001I-EN-P - January 2007