Execution order of function block diagram programs
During program execution, an instruction block is any element in the diagram, a network is a group of instruction blocks linked together, and the position of an instruction block is based on its top-left corner.
The following rules apply to the execution order of an FBD program:
- Networks are executed from left to right and top to bottom.
- All inputs must be resolved before executing the instruction block. When the inputs of two or more instruction blocks are resolved at the same time, the decision for the execution is based on the position of the instruction block (left to right and top to bottom).
- The outputs of an instruction block are executed recursively from left to right and top to bottom.
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