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jc_0653: Delay block layout in feedback loops

Since R2020a

Guideline Publication

Control Algorithm Modeling Guidelines - Using MATLAB®, Simulink®, and Stateflow®

Sub ID Recommendations

  • NA-MAAB — a

  • JMAAB — a

MATLAB Versions



Sub ID a

Delay block in feedback loops across subsystems shall reside in the hierarchy that describes the feedback loop.

Custom Parameter

Not Applicable

Example — Correct

Delay block resides in the hierarchy that describes the feedback loop.

Example — Incorrect

Delay block resides in a subsystem that is nested within the hierarchy which describes the feedback loop.


Sub ID a:

  • Prevents double placement of the Delay block.

  • Clarifying the extent of diversion improves reusability.

  • Improves testability; it is difficult to test a subsystem that contains a Delay block on its own because past values cannot be entered directly.


Model Advisor check: Check for avoiding algebraic loops between subsystems (Simulink Check)

Last Changed


Version History

Introduced in R2020a