SFC parallel branches
Parallel branches are used in SFC charts to represent parallel operations. Parallel branches occur when more than several steps are connected after the same transition. Parallel branches are drawn as double horizontal lines:
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When the transition before the divergence (1 on this example) is crossed, all steps beginning the parallel branches (101 and 201 here) are activated. Processing of parallel branches may take different timing according to each branch execution. The transition after the convergence (2 on this example) is crossed when all the steps connected before the convergence line (last step of each branch) are active. The transition indicates a synchronization of all parallel branches. If needed, a branch may be finished with an empty step (with no action). It represents the state where the branch "waits" for the other ones to be completed. |
You must take care of the following rules when drawing parallel lines in order to avoid dead locks in the execution of the program:
- All branches must be connected to the divergence and the convergence.
- An element of a branch must not be connected to an element outside the divergence.
SFC parallel branches |
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IEC 61131-3 Automation platform > Programming - Reference guide > Programming languages - Overview > Sequential Function Chart (SFC) > SFC parallel branches |
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