My understanding of one of the benefits of IoT Sitewise is you can model a specific machine type, and then use that same model across your fleet of machines. If you have two machines that use separate units of measurement, then you can use a Transform in the model to make them consistent. Assuming my understanding is accurate, my scenario is for Waterjet Cutters where one device reports temperature in Fahrenheit and the other in Celsius. My goal is to have the output from SiteWise be a single Property called Temperature and that all values will be Fahrenheit.
To go about this, I tried to create a Measurement called Temperature with the Unit of Fahrenheit. I then also created a Transform with the name Temperature and the unit of Fahrenheit. The idea is if the Asset is already using Fahrenheit, then I would Enable the Measurement and Disable the Transform. If the Asset is instead using Celsius, then I would disable the Measurement and Enable the Transform. That doesn't work as SiteWise reports the names across Measurements and Transforms must be unique. Outside of that approach, I am not sure how to accomplish what I am trying to do and the documentation doesn't cover this type of scenario. Do I need different models for different units of measurement?
I ended up getting the answer from a coworker and thought I would post it here if others encountered the same. For this scenario, I stored the unit of measure as a separate attribute, and then used a Conditional Function based on the Unit to decide whether or not to perform the conversion. Relevant documentation and screenshot below.
https://docs.aws.amazon.com/iot-sitewise/latest/userguide/expression-conditional-functions.html