From OT to AAS: making digital twins a reality
IIoT business models are based on digital twins of production assets such as machines and systems (OT). A standard for these twins is emerging with the Asset Administration Shell (AAS). It ensures interoperability, efficiency and future-proofing in the networked industry. New possibilities such as predictive maintenance, asset management and efficiency analyses arise when real asset data is integrated.
But how does data get from OT, i.e. the factory floor, to IT, i.e. the cloud, and how do assets automatically find their twins?
The reference architecture of the Open Industry 4.0 Alliance offers solutions for this. It divides the path into layers. The transition from the factory floor to the cloud takes place via an edge layer that connects the field level and IT. OT connectors retrieve data from field devices into the Open Edge Computing (OEC) environment and exchange it with other applications via a message bus. A cloud connector then transfers the data to the cloud, where the Asset Administration Shell (AAS) is managed.
OT assets are identified step by step:
- Fieldbus: identification via protocol functions or proprietary.
- OEC: Identification via the master asset model (e.g. vendor nameplate interface from OPC-UA).
- AAS: Identification via the digital nameplate (DNP).
Transformations are required between these identification formats, which are often difficult. Fieldbus protocols usually only provide serial numbers and device names, while the Master Asset Model and the DNP require much more detailed data, such as regulatory information or manufacturer contact data.
There are approaches to solving this: Manufacturers can provide missing data digitally, e.g. via an API or by supplying data directly to the customer. Unique identification of the asset is crucial, e.g. using the OI4Identifier. This includes the manufacturer's web address, model name, product code and serial number. Such data is often available in the fieldbus protocol or can be determined via ID comparisons.
For the transformation from master asset model to DNP, manufacturers could offer a reference AAS that provides all the necessary data.
Digital twins open up many business opportunities for the industry. With the OI4A reference architecture and the Asset Administration Shell, there are practical approaches - with room for customised solutions.
