Sequence steps

Each step in an Equipment Sequence diagram represents a specific action. Step types include initial steps,
Equipment Sequence
 steps, No phase steps, and end steps.
Initial step
Initial Step
The initial step is the starting point for an
Equipment Sequence
 and is automatically added to the beginning of a newly created
Equipment Sequence
 diagram. A sequence has only one initial step, which is a required step, and cannot be deleted.
When the sequence is commanded to START, this step becomes active.
Step
Phase step example
Each step represents one use of an
Equipment Phase
 to perform an action in the manufacturing sequence. A step has step tags that are input values which are loaded into the associated phase, and output values which are data loaded from the
Equipment Phase
.
Step input tag values are assigned to phase input parameters when the step is activated (automatically when configured on the
Equipment Phase
) and when requested by the phase’s logic.
Step output tags are assigned phase output parameter values when the phase becomes COMPLETE, STOPPED, or ABORTED (automatically when configured on the
Logix Designer
) and when requested by the phase logic.
A step is a separate entity from the Equipment Phase even though it refers to and commands an Equipment Phase. The Equipment Phase referenced in the step continues to execute until the logic in the transition transfers control to the next step.
No phase step
No-Phase Step
  • A No phase step is a step that does not have an associated
    Equipment Phase
    . It does not execute anything on its own, but is used to:
    • Prevent sequence steps in simultaneous divergent branches from having to start at the same time.
    • Prevent sequence steps in simultaneous convergent branches from being RESET and released at the same time.
    • Maintain the
      Equipment Sequence
       pattern of step-transition-step.
    • Separate adjacent branching structures.
End step
Terminal Step
The end step is the ending point for an
Equipment Sequence
 and automatically added to the end of a newly created equipment sequence diagram. A sequence has only one end step, which is a required step and cannot be deleted.
When the end step changes to COMPLETE, the
Equipment Sequence
 is complete.
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