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Data Latency (ms)Long

The time in milliseconds between MQTT Engine receiving of the last message and the payload's reported time.

A long latency time can indicate network issues.

Note: For this to be very accurate the edge node's clock and the system clock running MQTT Engine should be synced


Tip

A long latency time can indicate network issues.


Birth Count

Long

The number of NBIRTH messages since the last time the info metrics were reset via the Node Info/Reset Info tag

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  • Triggered by user
    • A rebirth request for the Edge Node was manually triggered at MQTT Engine
  • Message sequence number error

    • The message sequence number received was not in order 

      Tip

      Common cause:

      • In a Sparkplug compliant system, the combination of Group ID and Edge Node ID (the Sparkplug Edge Node Descriptor) that identifies the Edge Node must be unique. If there are two or more Transmitters with the same Sparkplug Edge Node Descriptor, 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. If you have multiple MQTT Clients subscribing to the namespace, this will also likely create a firestorm of rebirth requests across the system.


  • Received a message for an edge node that is offline

    • An NDATA message was received from an Edge Node that is marked as Offline at MQTT Engine.

      Tip

      Common causes:

      • A BIRTH message was not published by the Edge Node or was not received by MQTT Engine after marking the Edge Node Offline
      • There are two or more Transmitters with the same Sparkplug Edge Node Descriptor. A DEATH message has been received for one Edge Node marking the Edge Node Offline and subsequent data is received from another Edge Node with teh same Sparkplug Edge Node Descriptor.


  • Reordering sequence numbers

    • The message sequence number received was not in order after waiting the specified number of milliseconds after receiving an out of order message for the expected message to arrive.

      Tip

      Common cause:

      • The reordering timeout at MQTT Engine, configured to support clustered MQTT servers which do not support guaranteed in order delivery of QoS 0 messages, is not long enough for MQTT Engine to receive a message with the next sequence number. 


  • Unable to set Edge Node online
    • Explanation?
  • Failed to find metric name from alias
    • The alias in the DATA message did not match any alias previously published in the BIRTH message
  • UDT tag doesn't exist
    • UDT tag received in DATA message not found in previously published BIRTH messages
  • Unknown metric
    • Explanation?
  • DDATA before BIRTH
    • An DDATA message was received from an Edge Node Device that is marked as Offline at MQTT Engine


      Tip

      Common causes:

      • A DBIRTH message was not published by the Edge Node or was not received by MQTT Engine after marking the Edge Node Device Offline


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