Association templates, to link device features (measurements, alarms etc.) to Digital Twin Assets

The Digital Twin Manager is a powerful tool for defining asset "type" data models.

However, once an asset has been defined, the intuition and value of what a device represents begins to change...

Really, a device now only represents and endpoint in a network that is providing data to Cumulocity - in the form of measurements, events, alarms and manageObject fragments. Many if not all of these measurements, alarms and fragments really belong to assets and sub-assets in the Digital Twin asset hierarchy. The device itself is only helpful as a way to understand and monitor the data connectivity path.

To take the Digital Twin Manager to the next level, what is needed is a method to associate attributes of a device with elements of the subtree of an asset model.

For example: suppose a complex machine communicates with Cumulocity through a single Ethernet gateway device.

The machine consists of 3 pumps (each of which has a physical pump mechanism, a motor and a variable-speed drive), housed in an enclosure with temperature monitoring.

The gateway appears as a single device, and sends the following measurements to Cumulocity:

• Enclosure temperature

• Pump1 temperature

• Pump1 motor temperature

• Pump1 speed

• Pump1 power

• Pump1 temperature

• Pump2 motor temperature

• Pump2 speed

• Pump2 power

• Pump3 temperature

• Pump3 motor temperature

• Pump3 speed

• Pump3 power

These measurements are actually associated with a Digital Twin asset hierarchy like this:

• Pump system

  • Enclosure

    • {Enclosure temperature}

    • Pump1

      • Variable-speed drive

        • {Pump speed}

        • {Pump power}

      • Motor

        • {Motor temperature}

      • Pump mechanism

        • {Pump temperature}

    • Pump2

      • Variable-speed drive

        • {Pump speed}

        • {Pump power}

      • Motor

        • {Motor temperature}

      • Pump mechanism

        • {Pump temperature}

    • Pump3

      • Variable-speed drive

        • {Pump speed}

        • {Pump power}

      • Motor

        • {Motor temperature}

      • Pump mechanism

        • {Pump temperature}

What is needed now is a way to:

1. Form a link between device properties and the asset type to which they apply - a kind of "property map".

2. Recognise that, when a device of a certain type is connected to Cumulocity, that this implies that an instance of a certain asset subtree must be present, with an associated property map.