Handling Variants in Simulink Models the Smart Way
- Atul Abraham
- Aug 21
- 2 min read
Most of us dread handling variants in Simulink models, especially when we want to test different input sources or send signals to different destinations.
Traditionally, this is done by overusing variant signals and comparing them with constant enumeration values. While it works, the approach quickly becomes messy, difficult to maintain, and prone to errors.
Example Use Case: Switching Between Truck and Car Models
Imagine you are building a feature model that applies to both Trucks and Cars.
A common approach is to insert constants such as the enumeration TRUCK at multiple points in the model, combined with switch blocks to select the appropriate signals. Over time, this creates a cluttered design that is harder to scale.
Luckily, MATLAB and Simulink have a clean solution: the Variant Source blocks.
Variant Source – Choosing Among Inputs
The Variant Source block allows multiple alternative input signals to be connected to a single point in the model. Only one input is active at a time, determined by the variant control.
Think of it as a variant-aware smart switch.
Benefits:
Keeps the model neat and readable
Variant control logic is defined once in the data dictionary instead of being repeated across the model
How They Work
Both Variant Source and Variant Sink blocks use a variant control variable such as VARIANT. This variable is defined in a data dictionary.
If VARIANT = TRUCK, the model configures itself as the Truck version
If VARIANT = CAR, it configures as the Car version
This single point of control ensures consistent variant management across the entire model.
TLDR : Variant Source blocks bring clarity and scalability to models with multiple design alternatives. They make models easier to develop, test, and maintain.
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