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Overview

MQTT Engine has the ability to consume incoming Sparkplug messages and organize metrics to construct a Unified NameSpace.

Essentially, MQTT Engine obfuscates the Sparkplug descriptors, included in the Sparkplug topic, and uses the metric names from the payload to create the tags. This approach allows us to maintain all the benefits of Sparkplug while creating a clean implementation available for non Sparkplug Enterprise consumers.

Configuration

Configuration is set in the Sparkplug B namespace under MQTT Engine > Namespaces > Sparkplug B > Default > General as shown below:


How it Works

A Sparkplug message comprises two parts: the topic and the payload.

When configured to create UNS Tags, MQTT Engine will parse the metric name included in the payload to create the tag structure under the UNS Folder prefix.

The Sparkplug Descriptors in the topic are used to create three tag properties which identify the Sparkplug Descriptor associated with this tag: SparkplugGroupId, SparkplugEdgeNodeId and SparkplugDeviceId


The Sparkplug Descriptor properties, SparkplugDeviceId, SparkplugEdgeNodeId and SparkplugGroupID, for UDT Instance tags are inherited from the parent UDT Instance and can be viewed in the tag editor for the UDT Instance:

A requirement of a UNS is that each tag can only be referenced from a single source ie. the same tag path cannot be published from two edge nodes. 

To help identify colliding UNS tag, the SparkplugBPayloadHandler will at Error level when parsing a tag name that is already associated with a different Sparkplug Descriptor. 


In addition to creating the UNS folder, for each connected Edge Node, a Node Control and Node Info folder containing tags is created along with a Device Info folder for each connected device. See the Engine Tags documentation for details on each of these tags.

Under the Device Control and Node Control folders there is a "Delete UNS Tags" tag. This tag makes it simple to delete the tags for the respective Edge Node or Device without having to parse through the UNS tag tree to find the associated tags. The security on this tag is set to Read Only = True and will need to be updated to Read Only = False before the boolean can be written to.

MQTT Engine for Edge Node Site 1A


Example

Let's take a look at a an example of how a UNS can be created at MQTT Engine from Edge Node tags published by MQTT Transmission. 

Review the MQTT Transmission Transmitters and Tag Trees to gain an understanding of how MQTT Transmission Transmitter configurations interact with Ignition tag trees to publish Sparkplug messages and the immense flexibility that can be realized.


In the attached sample gateway backup, we have configured four tag providers to simulate four Edges - Site 1A, Site 1B, Site 1C and Site 2. 



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