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Overview

There are four primary components used in a system using IoT Bridge. These are:

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There are some translations that need to take place between the components and these platforms have different capabilities that result in some limitations in how an Edge Gateway can be configured. For example, UDTs in Ignition support more data types that AWS IoT SiteWise does. As a result, use of data types in Ignition must be limited to those supported by AWS IoT SiteWise in order for data to properly show up and be updated in AWS SiteWise.

Mappings

Ignition and AWS IoT SiteWise use different terminology for similar constructs. Those definitions are below.

  • An Ignition 'UDT Definition' is mapped to a SiteWise 'Asset Model'.
  • An Ignition 'UDT Instance' is mapped to a SiteWise 'Asset'.
  • Ignition 'UDT parameters' are mapped to 'SiteWise Attributes'.
  • Ignition 'UDT member tags' are mapped to 'SiteWise Measurements'.
  • Transform, Metric, and Hierarchy definitions in AWS SiteWise are not used by IB.

Constraints and Limitations

Supported Data Types

AWS IoT SiteWise only supports Booleans, Integers, Doubles, and Strings. As a result, this is the list of data types in Ignition that are supported for consumption into AWS IoT SiteWise

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These are not supported currently in IoT Bridge. AWS SiteWise allows Asset Models to have one or more child Asset Models. Ignition supports UDTs having children UDTs as well as UDTs referencing a parent UDT. However, these hierarchical relationships will not be maintained by IB. Support for simple hierarchies as supported by AWS IoT SiteWise will be added in a future version of IoT Bridge.

AWS IoT SiteWise Limits and Quotas

AWS IoT SiteWise has limits and quotas on many different aspects of asset model counts, asset counts, number or attributes per model, etc. For details on those limits see this document.

MQTT Server

  • AWS IoT Core has a maximum message size limited to 128 kiloBytes. This limitation can be overcome by using the Cirrus Link Chariot MQTT Server.
  • AWS IoT Core does not support use of Sparkplug's 'Primary Host ID' feature. This limitation can be overcome by using the Cirrus Link Chariot MQTT Server.

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