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In the video below As an example we have two transmitters physical Edge Nodes setup with a single Transmitter configured on each.

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The Ignition tag tree of structure is Company/Location/Process Area/Line/PLC where Line is the physical Edge Node device. With the tag path for the transmitter both transmitters set to My Company, we can see that both edge nodes Edge Nodes will publish on the following namespaces:

spV1Transmitter on Edge 1 named Lakeside Finished Goods Line 1           spV1.0/Lakeside/message_type/Finished Goods/Line1

spV1Transmitter on Edge 2 named Lakeside Finished Goods Line 2           spV1.0/Lakeside/message_type/Finished Goods/Line2

Since the group_id (Lakeside) and edge_id (Finished Goods) does not uniquely define the edge node, data from these two transmitters will sent with the same topic resulting in the next message sequence number expected by the MQTT client being incorrect.

As a result, the MQTT Client will mark the data as stale and request a rebirth from the transmitter. Depending on the frequency of the published data this manifests as the data from different edge nodes toggling between stale and healthy. If you have multiple MQTT Clients subscribing to the namespace, this will also likely create a firestorm of rebirth requests across the system.

We will use the logging associated with your Chariot or MQTT Engine instance to determine the physical or virtual Edge Nodes with duplicate Group and Node IDs.

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