Array as value of OPC node to SiteWise Assets

This is not a supported data type as of today. For now as a workaround, you can wrap it as a string and put a iot core rule that reads the string and formats the data to your needs and pushes back to sitewise. Might not be a good fit for high frequency data. Below link has the available data types for measurements:

https://docs.aws.amazon.com/iot-sitewise/latest/userguide/measurements.html