# Only 2 out of 4 cameras are detected

Source: https://forum.modalai.com/topic/4951/only-2-out-of-4-cameras-are-detected
Category: General Questions (https://forum.modalai.com/category/2/general-questions)
Posted: 2025-12-24 17:42:06 UTC by Piyush Singh
Replies: 1 · Views: 287

## Piyush Singh · 2025-12-24 17:42:06 UTC

Hello ModalAI Team,

I am working on an indoor drone using VOXL2 Mini, and I would appreciate your guidance regarding a camera detection issue with a multi-sensor setup.

Goal

My goal is to build an indoor drone, primarily relying on visual sensing rather than GPS.

Camera Modules Used

- M0169 – PMD ToF
- M0014 – Tracking Camera
- M0024 – High-Resolution Camera

Hardware Connections

- J6 → M0084
   - JU: PMD-ToF (external 5V power supplied to M0169)
   - JL: High-Resolution Camera
- J7 → M0135
   - JU: Tracking Camera
   - JL: Tracking Camera

Observed Issue

When using a custom camera configuration file, "voxl-camera-server" detects only 2 out of 4 cameras:

- Detected: High-Resolution + Tracking (Down)
- Not detected: PMD-ToF + Tracking (Second unit)

Debug Information

While debugging, I consistently get the following error:

ToF resolution not supported (224 × 1557)
And Tracking front is not detected.

To address this, I manually modified "/etc/modalai/voxl-camera-server.conf":

- "preview_width": 240
- "preview_height": 180

After restarting "voxl-camera-server", the error still persists(Resolution error), and only 2 cameras are detected.

My Questions

1. From an indoor drone perspective, is my approach of using 4 camera sensors (ToF + dual tracking + high-resolution) correct, or would you recommend a different sensor combination?
2. Why are only 2 cameras detected despite all 4 being connected correctly?
3. Why does the ToF camera still report an unsupported resolution (224 × 1557) even after manually setting the preview resolution?
4. Is there any additional configuration required for PMD-ToF when used alongside multiple cameras on VOXL2 Mini?

Any guidance, recommended configuration, or known limitations would be very helpful.

## Reply by Moderator (ModalAI staff) · 2025-12-27 19:51:11 UTC

@Piyush-Singh Have you tried ```voxl-camera-server -d0``` found here https://docs.modalai.com/voxl-camera-server/#troubleshooting ?

You cannot plug in cameras arbitrarily, you'll need to use one of the supported camera configurations: https://docs.modalai.com/voxl2-camera-configs/