Capability rfid devices in smart library ontology to instantiate Digital Twin

Question

Hi,

i'm implementing an ontology for a Digital twins project related to a rfid system for a public library.

I'm following the the open-source Smart Building **RealEstateCore ontology **as model for smart library; i think it'a great model that complies with standards.

I'm going to instantiating the following twins about rfid system:

rfid gate (to check rfid library item) ,

rfid programming station (to program and enable/disable tag allarm code)

rfid Self-server kiosk (to self service borrow and return library item)

their components (antenna, tag reader/writer, host device, ..), etc..

I'm not sure about CAPABILITY functions used in the ontology; look at https://github.com/Azure/opendigitaltwins-building/blob/master/Documentation/Capability-README.md ; in particular my system works using electomagnetic induction (tag with 13.56 Mhz communication frequency). Beyond elettromagnetic induction, i think it's more interesting to monitor converted data in hexbin format stored in tags (using Danish model) applied in libary item and read from indicated devices.

According to you, which could be the most suitable choise according to ontology model for capability?

A rfid reader/writer component as capability SENSOR ? What KIND?

Data comes from conversion electomagnetict to digital.

Is it possibile to use any IoT template for this purpose?

Other questions.

Data row are stored in tag in Danish model and encoded in my ontology as hex Binary data type in owl format. For example some library item data read from tags are :

'Part Number Field' only xsd:hexBinary

'Owner Library Field' only xsd:hexBinary

I'm converting ontology using OWL2DTLS converter

https://github.com/Azure/opendigitaltwins-tools/tree/main/OWL2DTDL

with some adjustments to the final json files to use as model.

If you look in

https://learn.microsoft.com/en-us/azure/digital-twins/concepts-models#properties-and-telemetry

hexBinary type doesn't exist.

https://github.com/Azure/opendigitaltwins-dtdl/blob/master/DTDL/v2/DTDL.v2.md#field

Which telemetry schema should i use? Array with string?

I am available for any clarification.

Thanks in advance.

Guido

Answer 1

Hello,

It sounds like you are on the right track with using the RealEstateCore ontology as a model for your smart library.

• As for the capabilities, it seems like a good fit to use the "Sensor" capability for your RFID reader/writer component, since it is gathering data through electromagnetic induction.
• In terms of the data format, since hexBinary is not directly supported by Digital Twins, you can represent it as a string data type in your telemetry schema. You can choose to send the hexBinary data as an array of strings or as a single string.
• It's important to consider the data volume and frequency of updates when designing your telemetry schema. You can use the DTDL language to define the telemetry schema for your Digital Twins instance, and you can find more information on the syntax and available data types in the DTDL documentation.
• As for IoT templates, Azure provides a number of IoT solutions and templates that can be used as a starting point for your project. You can browse the Azure IoT Solutions catalog for ideas and inspiration.

Overall, it seems like you have a good understanding of your project and the technologies involved. I would recommend continuing to explore the documentation and resources available to you, and don't hesitate to reach out on this forum for support and guidance along the way.