Contents
Cirrus Link Resources
Cirrus Link Website
Contact Us (Sales/Support)
Forum
Cirrus Link Modules Docs for Ignition 7.9.x
Inductive Resources
Ignition User Manual
Knowledge Base Articles
Inductive University
Forum
Page History
...
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:
...
| Tip |
|---|
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. |
We have configured an MQTT Transmission Transmitter to use the Ignition tag tree in the default tag provider at the Edge to construct the Sparkplug Device Descriptor (group_id, edge_id and device_id) starting at the folder level below Edge Nodes.
For the Ignition tag tree below, the topic and payload for a change to tag T1 will be:
Topic: spBv1.0/G1/DDATA/E1/D1
SparkplugBPayload: [timestamp=1726851053618, metrics=[Metric [name=Vancouver/Area1/Line1/Zone1/Asset1/T1, alias=null, timestamp=1726851052615, dataType=Int32, isHistorical=null, isTransient=null, metaData=null, properties=PropertySet [propertyMap={}], value=10, isNull=false]], seq=3, uuid=null, body=null]
At MQTT Engine, the metric name is parsed and the tag structure created under the configured UNS folder name.
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 custom tag
...
properties which identify the Sparkplug Descriptor associated with this tag:
...
SparkplugGroupId
...
, SparkplugEdgeNodeId
...
Edge
MQTT Engine
MQTT Engine
...
and SparkplugDeviceId
| Tip |
|---|
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:
|
...
Currently it is possible to manually edit the Sparkplug Descriptor properties for a UNS tag at MQTT Engine. The edits will hold until a BIRTH message is received from the Edge Node.
These tags are not used internally by MQTT Engine and the tag will remain associated with the original Sparkplug Descriptor. For example if the SparkplugDeviceId associated with Vancouver/Area1/Line1/Zone1/Asset1/T1 is changed to D17, new data coming in from spBv1.0/G1/DDATA/E1/D1 for metric Vancouver/Area1/Line1/Zone1/Asset1/T1 will still be written to the tag.
| Note |
|---|
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 log 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
...
Colliding Tag Paths
| Warning |
|---|
| 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.
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.
| Tip |
|---|
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.
At Engine, we can see how the tags published from Edge Nodes Site 1 A, Site 1 B and Site 1 C have been concatenated under the single UNS tag path of UNS> Enterprise > Site 1
...
Overview
Content Tools