Page History

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MQTT Transmission Store and Forward Not Enabled

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1. Transmission connects and publishes its BIRTH

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1. 1. The timestamp for Tag1 set at the Edge to 'now' per the Edge's system clock.
      

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1. 1. 
      
2. Tag change events occur naturally at the Edge

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1. 1. During this time the timestamp is always set using the tag change event time at the Edge. This results in Tag1's timestamp at Engine matching that of the Edge.
      

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2. Transmission loses connection.
   1. At this point, Engine 'stales' the tag by setting the quality to BAD_STALE and sets the timestamp of Tag1 to 'now' per the Central Gateway's system clock.

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1. 1. The tag may or may not be changing at the Edge - Engine won't know in real time this is happening

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1. 1. so it sets the quality of

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1. 1. Tag1 to BAD_STALE.

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1. 1. 
      
      
2. Transmission reconnects and publishes its BIRTH

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1. 1. The timestamp for

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1. 1. Tag1 set at the Edge to 'now' per the Edge's system clock.
   2. Assuming the quality of

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1. 1. Tag1 at the Edge is GOOD - it will be set to GOOD at Engine.
   2. If the tag value had never changed at the Edge

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1. 1. , then you would see three events with the same value, three different timestamps, and the quality go from GOOD -> BAD_STALE -> GOOD.