Selective topology
A selective topology has two or more alternate paths in which only one path is selected for execution. In a selective branch, only the step in the path or branch under the first transition to evaluate as TRUE is executed. Other paths or branches are ignored. Sequence execution continues in the selected path until that path's final transition.
TIP:
Select the initial step link before adding the step and transition pair and the link automatically connects to the pair.
The example shows an Equipment Sequence diagram that uses a selective topology.
Item | Name | Description |
 | Initial step | When the sequence is commanded to START, this step becomes active. |
 | Selective divergence | The starting point for a selective branch is a selective divergence. When you add a selective divergence, attach a transition to begin each alternative execution path. At runtime, the first transition in each divergent path is evaluated. The first transition to evaluate TRUE deactivates the other transitions and activates the step following it. Sequence execution continues in the selected path until the selective convergence is met. |
 | First transition in the selective branch | The first transition following the selective branch to evaluate as TRUE determines the execution path. |
 | First step in selective branch | Only the steps in the path with the first transition to evaluate as TRUE become active. |
 | Last transition in branch path | After the final transition in the execution path evaluates as TRUE, sequence execution continues in the merged path. |
 | Selective convergence | The ending point for a selective branch is a selective convergence. When you add a selective convergence, the final transition of each divergent path is linked to the branch. At runtime, after the final transition in the selected path is evaluated, execution continues in the merged path. |
 | End step | When the end step changes to COMPLETE, the Equipment Sequence becomes complete. |
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