Modern Testing Starts in Software, Not Hardware

Why the shift from HiL to SiL is redefining test infrastructure and giving embedded teams a faster, smarter way to validate software.

Michael Zigldrum

May 28, 2025

For a long time, embedded testing meant one thing: hardware. HiL benches were the default. But in today's fast-moving product cycles, that model is starting to crack.

Teams are shifting to Software-in-the-Loop (SiL) validation because it’s faster to run, easier to scale, and gives better feedback at the exact point when developers need it. HiL still plays a critical role, but it’s no longer where modern testing begins.

“They didn’t even know it was possible—until we showed them overnight test results from 150 SiL instances running in parallel.”

The Limits of HiL and the Promise of SiL
What SiL Enables
HiL Still Matters. But It Has a New Role
How Aturo Supports This Shift

1. The Limits of HiL and the Promise of SiL

HiL is excellent for testing how software interacts with physical hardware. But when used for logic validation, it becomes a bottleneck. It is slower, harder to scale, and more costly to maintain.

I remember working with an object detection team that couldn’t get enough throughput on their HiL setups. During the holidays, I quietly added SiL execution support to our test platform. A week later, we showed them the results: 150 servers running simulations overnight on a dataset far larger than what they could handle before.

The reaction was instant. They hadn’t realized this was an option. That moment made it clear—what teams need is the ability to validate early and often, without hardware getting in the way.

2. What SiL Enables

With SiL in place, testing goes from a resource bottleneck to an everyday habit. Teams can validate logic on every commit, get results overnight, and parallelize execution without worrying about hardware queues.

It unlocks:

Continuous testing for logic
Large-scale scenario coverage
Reduced iteration cost
Cleaner and more traceable test data
Smaller teams doing more with less infrastructure

And when testing becomes easier, teams test more often. They find issues earlier, fix them faster, and avoid long debugging cycles.

3. HiL Still Matters, But It Has a New Role

We are not saying HiL is obsolete. Quite the opposite. But its role is changing.

HiL is best used to catch integration issues or hardware-specific behaviors that cannot be simulated. SiL, on the other hand, is perfect for validating logic in isolation, across many scenarios, quickly.

The smart approach is to handle logic validation through SiL first, then use HiL for late-stage hardware interaction tests. The exact handover point varies, but in every team we've worked with, the shift has trended in one direction: toward a SiL-first model.

4. How Aturo Supports This Shift

Aturo does not replace your test logic or simulation models. Instead, we help you run them more effectively, at scale, and with full traceability.

Our platform lets teams:

Orchestrate SiL and HiL tests across environments
Automatically track test data and software artifacts
Apply data retention and access policies
Maintain auditability across the entire validation flow

We believe modern testing should be scalable, traceable, and efficient. That starts in software, not hardware.