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Sentech Cams Node ​

Overview ​

The Sentech Cams node provides hardware integration with Sentech camera devices. It manages Docker containers that interface with Sentech cameras, handling automatic startup, cleanup, and multi-camera coordination through shared memory communication.

Key Features ​

  • Multi-camera support: Control multiple Sentech cameras simultaneously
  • Docker-based: Isolated containers per camera
  • Auto-start: Optional automatic startup on deployment
  • Shared memory: Fast inter-process communication via /dev/shm
  • Driver management: Ensures Sentech driver container is running
  • Color mode selection: RGB or BGR output
  • Device ID configuration: Specify cameras by MAC address

Hardware Requirements ​

  • Sentech camera hardware
  • Sentech camera driver installed
  • Docker and Docker Compose
  • Root/sudo access for Docker operations
  • /opt/rosepetal-sentech directory with Docker Compose config
  • /opt/rosepetal-sentech-driver directory with driver setup

Configuration ​

Properties ​

Auto Start ​

  • Type: Checkbox
  • Default: false
  • Description: Automatically start cameras on node deployment

Auto Start Delay (seconds) ​

  • Type: Number
  • Default: 6
  • Description: Delay before starting cameras (allows system initialization)

Device IDs ​

  • Type: Array of strings
  • Default:
    javascript
    [
  "d4:7c:44:31:5f:62",
  "d4:7c:44:31:5f:61",
  "d4:7c:44:31:5f:68",
  "d4:7c:44:31:5f:bb"
]
  • Description: MAC addresses of Sentech cameras to control

Color Mode ​

  • Type: Select
  • Options: BGR, RGB
  • Default: BGR
  • Description: Output color format for captured images

Input ​

Control Messages ​

Start Cameras ​

javascript
msg.payload = { action: "start" };

Starts Docker containers for all configured cameras.

Stop Cameras ​

javascript
msg.payload = { action: "stop" };

Stops and removes all camera Docker containers.

Cleanup ​

javascript
msg.payload = { action: "cleanup" };

Performs full cleanup:

  • Kills SaveAnd processes
  • Stops Docker containers
  • Cleans shared memory
  • Resets permissions

Operations ​

Startup Sequence ​

  1. Cleanup existing: Remove old processes and containers
  2. Verify driver: Ensure driver container is running
  3. Start driver: Launch driver container if needed (5s wait)
  4. Start cameras: Launch container for each device ID
  5. Set status: Update node status indicators

Container Management ​

Each camera gets a dedicated Docker container:

  • Container name: sentech-app-{device-id}
  • Environment variables: DEVICE_ID, COLOR_MODE
  • Shared memory: /dev/shm for inter-process communication

Cleanup Process ​

Cleanup involves:

  1. Kill all SaveAnd processes
  2. Stop Docker Compose services
  3. Remove shared memory files (/dev/shm/S_*, /dev/shm/LOG_*)
  4. Set proper permissions (chmod 1777 /dev/shm)

Node Status ​

StatusMeaning
Grey dot - "idle"Node ready, cameras not started
Yellow dot - "starting..."Cameras starting up
Green dot - "running: N camera(s)"N cameras running successfully
Red ring - "startup error"Error during startup
Orange dot - "stopping..."Cameras shutting down
Blue dot - "stopped"Cameras stopped successfully

Usage Examples ​

Example 1: Auto-Start on Deploy ​

Configuration:

  • Auto Start: Enabled
  • Auto Start Delay: 6 seconds

Behavior: Cameras automatically start 6 seconds after flow deployment

Example 2: Manual Control ​

[Inject: Start Button] → [Sentech Cams]
[Inject: Stop Button] → [Sentech Cams]

Start button:

javascript
msg.payload = { action: "start" };
return msg;

Stop button:

javascript
msg.payload = { action: "stop" };
return msg;

Example 3: Scheduled Operation ​

[Inject: Daily 8AM] → [Function: Start] → [Sentech Cams]
[Inject: Daily 6PM] → [Function: Stop] → [Sentech Cams]

Automatically start cameras at 8AM and stop at 6PM.

Example 4: Cleanup Before Restart ​

javascript
// Function node
// Send cleanup first
node.send([{ payload: { action: "cleanup" } }, null]);

// Wait 5 seconds, then start
setTimeout(() => {
  node.send([null, { payload: { action: "start" } }]);
}, 5000);

Docker Requirements ​

Required Docker Compose Files ​

/opt/rosepetal-sentech/docker-compose.yml:

yaml
version: '3'
services:
  app:
    image: sentech-app:latest
    container_name: ${dockerName}
    environment:
      - DEVICE_ID=${DEVICE_ID}
      - COLOR_MODE=${COLOR_MODE}
    volumes:
      - /dev/shm:/dev/shm
    network_mode: host

/opt/rosepetal-sentech-driver/docker-compose.yml:

yaml
version: '3'
services:
  driver:
    image: sentech-driver:latest
    container_name: sentech-driver
    privileged: true
    network_mode: host

Docker Images ​

Required images:

  • sentech-app:latest - Camera application
  • sentech-driver:latest - Sentech camera driver

Build and tag appropriately before use.

Shared Memory ​

Purpose ​

Shared memory (/dev/shm) enables fast communication between:

  • Camera driver
  • Camera application containers
  • Node-RED (via Camera Manager node)

Files ​

Pattern: /dev/shm/S_{device-id}, /dev/shm/LOG_{device-id}

Example:

  • /dev/shm/S_d4-7c-44-31-5f-62
  • /dev/shm/LOG_d4-7c-44-31-5f-62

Permissions ​

Must have permissions: 1777 (chmod 1777 /dev/shm)

Integration with Camera Manager ​

The Sentech Cams node starts camera processes, while Camera Manager node captures images:

[Sentech Cams: Start] → [Wait 10s] → [Camera Manager: Capture]

Flow:

  1. Sentech Cams: Start camera containers
  2. Wait: Allow cameras to initialize
  3. Camera Manager: Read from shared memory and capture

Error Handling ​

Common Errors ​

"Failed to start container" ​

Causes:

  • Docker image not available
  • Port conflict
  • Insufficient permissions

Solutions:

  • Verify Docker images exist
  • Check no conflicting containers
  • Run with sudo/root permissions

"Driver container not running" ​

Causes:

  • Driver image not available
  • Driver failed to start

Solutions:

  • Check driver image exists
  • Review driver logs
  • Manually start driver container

"SHM cleanup error" ​

Causes:

  • Files locked by processes
  • Permission denied

Solutions:

  • Kill all camera processes
  • Run cleanup with sudo
  • Reboot system if persistent

Debugging ​

View container logs:

bash
docker logs sentech-app-d4-7c-44-31-5f-62
docker logs sentech-driver

Check shared memory:

bash
ls -la /dev/shm/S_*
ls -la /dev/shm/LOG_*

Check running containers:

bash
docker ps | grep sentech

Best Practices ​

  1. Auto-start delay: Use at least 5-6 seconds for system initialization
  2. Cleanup regularly: Run cleanup before major changes
  3. Monitor logs: Check Docker logs for errors
  4. Proper shutdown: Always use stop action before redeployment
  5. Device IDs: Verify MAC addresses match actual hardware
  6. Permissions: Ensure proper /dev/shm permissions

Security Considerations ​

  • Root access: Node requires sudo for Docker operations
  • Network mode host: Containers use host networking
  • Shared memory: Accessible to all processes
  • Production: Review security implications for production deployments

Troubleshooting ​

Cameras not starting ​

Check:

  1. Docker service running
  2. Images exist locally
  3. Device IDs correct
  4. No port conflicts
  5. Sufficient system resources

Intermittent failures ​

Check:

  1. Shared memory not full
  2. No zombie processes
  3. Driver container healthy
  4. Network connectivity

Performance issues ​

Check:

  1. System CPU/memory usage
  2. Number of concurrent cameras
  3. Shared memory throughput
  4. Docker container resources

See Also ​