Question

In a Sequential Function Chart, what determines the transition from one state to the next when multiple parallel branches are used?

Accepted Answer

In a Sequential Function Chart, the transition from one state to the next when using parallel branches is determined by the fulfillment of the transition condition associated with each branch. A parallel branch occurs when a single transition line splits into multiple paths that run simultaneously. Each individual path in a parallel branch starts with a step and must contain its own transition condition. For the system to move from the current state into the parallel branches, the transition condition immediately preceding the divergence must evaluate to true. Once the process enters the parallel branches, each path functions independently. A step within a parallel branch remains active until its specific associated transition condition evaluates to true. Once all parallel branches reach their final steps and the transition condition immediately following the convergence point is met, the system transitions to the next step. A transition condition is a logical expression, such as a sensor input or a timer, that must be true for the flow to pass through the transition line. A step represents a specific state or action in the sequence. Convergence occurs when the separate parallel paths merge back into a single path, requiring all concurrent branches to be finished before the process can continue to the next state.

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In a Sequential Function Chart, what determines the transition from one state to the next when multiple parallel branches are used?