> This page is for version 1.4.0 (Latest) (default).
> For other versions, use one of these documentation indexes:
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> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.nvidia.com/halos/outside-in-safety/llms.txt.
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# Software-in-Loop Testing

Welcome to the closed-loop testing guide, covering the **Software-in-the-Loop (SIL)** harness and its workflows.

Closed-loop testing enables end-to-end validation of the Halos safety system using Isaac Sim simulation before deploying to production hardware. This approach accelerates development, reduces costs, and enables testing of dangerous scenarios in a safe environment.

Two quick starts bring up the environment, differing only in the perception
profile they drive. Start from [SIL — 2D Perception](/halos/outside-in-safety/testing/sil/sil-2d), which uses the VSS 2D profile:
one pipeline per camera, the simplest setup, and the highest frame rate. Use
[SIL — 3D Perception](/halos/outside-in-safety/testing/sil/sil-3d) when you need the 3D (BEV) profile, where VSS groups several
cameras into a single bird's-eye sensor. Either way, return here afterwards for
the architecture and component detail.

## Overview

This documentation covers:

* **Quick Starts**: Bring up the closed loop on 2D or 3D perception
* **SIL Overview**: Understanding the simulation-based testing approach
* **SIL Prerequisites**: Hardware and software requirements
* **SIL Architecture**: Detailed system design and data flow
* **Components**: Deep dive into Isaac Sim, the Action Graphs, and the forklift controller

## Getting Help

If you encounter issues:

* Check the troubleshooting sections in each guide
* Review the component-specific documentation
* Contact the Halos development team

## Related Documentation

* [Integration Guide](/halos/outside-in-safety/integration) - Integration Guide
* [Deployment Guide](/halos/outside-in-safety/deployment) - Deployment Guide
* [Deploy AI Perception](/halos/outside-in-safety/getting-started/inference-pipeline) - Deploy AI Perception