cgw.md

6.9 Cloud Gateway (CGW)

Overview

The Cloud Gateway (CGW) bridges the local factory MQTT broker with the fischertechnik Cloud, enabling remote monitoring and control. It acts as a bidirectional MQTT message forwarder.

Module Type: CGW (special infrastructure component)
Serial Number: Cleaned variant of the SPS serial number
Function: MQTT bridge, not a production module

6.9 Architecture

The CGW acts as a bridge between the local factory network and the cloud.

graph TD
    subgraph Cloud
        Dashboard[Cloud Dashboard]
    end
    
    subgraph Local_Factory
        CGW[CGW Module<br/>Cloud Gateway]
        CCU[CCU]
        Broker[Local MQTT Broker]
    end
    
    Dashboard <-->|Internet/MQTT| CGW
    CGW <-->|Local Network| Broker
    CCU <-->|Local Network| Broker

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Topic Forwarding Rules

The CGW selectively forwards topics between local and cloud brokers.

From Local Broker to Cloud

Messages from the factory are forwarded to the cloud with prefix /j1/txt/<cloud-controller-id>/:

Local Topic	Cloud Topic
ccu/order/response	/j1/txt/<id>/ccu/order/response
ccu/order/active	/j1/txt/<id>/ccu/order/active
ccu/order/completed	/j1/txt/<id>/ccu/order/completed
ccu/pairing/state	/j1/txt/<id>/ccu/pairing/state
ccu/state/#	/j1/txt/<id>/ccu/state/#
fts/v1/ff/+/connection	/j1/txt/<id>/fts/v1/ff/+/connection
fts/v1/ff/+/state	/j1/txt/<id>/fts/v1/ff/+/state
fts/v1/ff/+/factsheet	/j1/txt/<id>/fts/v1/ff/+/factsheet
module/v1/ff/+/connection	/j1/txt/<id>/module/v1/ff/+/connection
module/v1/ff/+/state	/j1/txt/<id>/module/v1/ff/+/state
module/v1/ff/+/factsheet	/j1/txt/<id>/module/v1/ff/+/factsheet

Additionally, dashboard-related topics: | /j1/txt/1/f/i/# | /j1/txt/<id>/f/i/# | | /j1/txt/1/i/# | /j1/txt/<id>/i/# |

From Cloud to Local Broker

Messages from the cloud are forwarded to the local broker with prefix removed:

Cloud Topic	Local Topic
/j1/txt/<id>/ccu/order/request	ccu/order/request
/j1/txt/<id>/ccu/order/cancel	ccu/order/cancel
/j1/txt/<id>/ccu/pairing/pair_fts	ccu/pairing/pair_fts
/j1/txt/<id>/ccu/set/#	ccu/set/#

Dashboard-related topics: | /j1/txt/<id>/f/o/# | /j1/txt/1/f/o/# | | /j1/txt/<id>/o/broadcast | /j1/txt/1/o/broadcast | | /j1/txt/<id>/o/ptu | /j1/txt/1/o/ptu | | /j1/txt/<id>/c/# | /j1/txt/1/c/# |

Configuration

The CGW is configured through:

1. fischertechnik Cloud Pairing:

   • Performed via TXT Controller UI
   • Generates cloud credentials
   • Assigns <cloud-controller-id>

2. Local Broker Configuration:

   • Hardcoded in data/config.json inside .ft project
   • Contains local broker IP and credentials

Example config.json:

{
  "mqtt": {
    "localBroker": {
      "host": "192.168.0.100",
      "port": 1883,
      "username": "default",
      "password": "default"
    },
    "deviceId": "CGW001"
  }
}

Cloud Controller ID

The <cloud-controller-id> is obtained during the fischertechnik Cloud pairing process:

• Unique identifier for this factory instance in the cloud
• Used as topic prefix for all cloud messages
• Replaced with local ID 1 for dashboard compatibility

Use Cases

Remote Monitoring

External systems can monitor the factory via cloud topics:

• Subscribe to /j1/txt/<id>/ccu/state/# for factory state
• Subscribe to /j1/txt/<id>/module/v1/ff/+/state for module states
• Subscribe to /j1/txt/<id>/fts/v1/ff/+/state for AGV positions

Remote Control

Send commands through the cloud:

• Publish to /j1/txt/<id>/ccu/order/request to create orders
• Publish to /j1/txt/<id>/ccu/set/# for configuration changes

Dashboard Access

The fischertechnik dashboard can connect remotely:

• Uses special /j1/txt/<id>/f/o/# and /c/# topics
• CGW translates between cloud ID and local ID 1

MQTT Topics (CGW Itself)

The CGW does not publish state like production modules. However, it appears in the system with:

Connection Topic: module/v1/ff/<serial>/connection

Online Message:

{
  "headerId": 1,
  "timestamp": "2024-12-08T09:00:00.000Z",
  "version": "1.0.0",
  "ip": "192.168.0.50",
  "manufacturer": "fischertechnik",
  "serialNumber": "CGW001",
  "connectionState": "ONLINE"
}

Security Considerations

Local Network

• Local MQTT typically uses simple authentication (default/default)
• ⚠️ Not intended for public exposure
• Should be on isolated factory network

Cloud Connection

• TLS encryption for cloud communication
• Authenticated via fischertechnik Cloud credentials
• Credentials generated during pairing process

Topic Filtering

• CGW only forwards specific topics
• Prevents unintended message leakage
• Maintains separation between local and cloud concerns

Operational Notes

Requirements

Both credentials must be configured:

1. Local Broker: IP and login hardcoded in config
2. Cloud Credentials: Generated via TXT Controller pairing UI

Startup

On startup, CGW:

1. Connects to local MQTT broker
2. Connects to fischertechnik Cloud MQTT broker
3. Subscribes to relevant topics on both brokers
4. Begins forwarding messages

Error Handling

If connection fails:

• CGW retries connection automatically
• Messages may be lost during disconnection
• No local queueing of cloud-bound messages

Debugging

To debug CGW operation:

• Monitor both local and cloud brokers
• Check topic prefixes are correct
• Verify CGW connection status
• Review CGW logs on TXT Controller

Limitations

1. No State Buffering: Messages lost during disconnection are not recovered
2. One-Way Real-Time: Not designed for request-response patterns
3. Topic Whitelist: Only predefined topics are forwarded
4. No Message Transformation: Messages are forwarded as-is (except topic prefix)

Development and Testing

Local Testing Without Cloud

For development without cloud connection:

• Disable CGW
• Use local MQTT broker only
• All functionality works locally

Cloud Testing

For testing cloud integration:

• Use MQTT client to connect to cloud broker
• Subscribe to /j1/txt/<id>/# to see all forwarded messages
• Publish to /j1/txt/<id>/ccu/order/request to test remote control

Related Documentation

• System Architecture
• General Module Overview
• Message Structure
• Calibration
• Manual Intervention