Execution order and feedback loops - Grid automation - Engineering Manual - REC615 Grid Automation Protection and Control - RER615 Grid Automation Protection and Control - Relion 615 series - 2.0 - IEC - ANSI - 28.04.2023

REC615 and RER615 Engineering Manual

It is possible to draw multi-layer configuration logic that contains feedback loops with the Application Configuration tool. The execution order of logic functions is calculated automatically in the Application Configuration tool, but the execution order can also be set manually. If the automatically calculated value causes the function to be executed one task cycle time after the other logic functions in the same loop, the execution order number can be set manually to prevent delays, for example, in output activation.

Note: To perceive accurate time stamps from binary input signals to function blocks, direct logic connection should be used in the Application Configuration tool. Due to internal execution order, time stamps may not be accurate if additional logic is used to connect priority signals to function blocks.

Example shows a simple situation where the execution order causes one cycle time delay if the NOT port is executed in the order determined by the automatic calculation.

Figure 1. Feedback loop situation with automatically calculated execution orders
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By setting a smaller execution number than in the AND port to where the NOT port is connected, it is possible to fix the execution order of all functions in a loop so that they are handled in the same task.

Figure 2. Feedback loop situation with manually fixed execution order for NOT port
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Execution number can be changed by right-clicking the function and selecting Change CycleTime ExecOrder.

After manually defining the execution number, the function is no longer part of the automatic execution order calculation. The function can be included back to the automatic calculation by right-clicking the function and selecting Include FB in calculation.