SmartSwarm 300 Series
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10. RULES AND TOPICS
10.1 INTRODUCTION
The SmartSwarm 351 converts Modbus data to MQTT.
In the process it adds data enrichment, including scaling factors and meta-data.
By default, all data is blocked and nothing is published on MQTT until you specifically allow it.
Bear in mind that even a slow serial network, running continuously, can create a lot of data. A 9600-baud network
running at 50% bus utilization generates 1.5GB of raw data every month: and this is significantly increased by the
enrichment process. If you are transporting the MQTT data over cellular you probably cannot afford to publish
everything, and it is unlikely that your cellular connection and cloud service would keep up with the sustained,
enriched-data rate.
The “Decoder” interface on SmartWorx Hub enables you to first apply enrichment for your Modbus data, and then
to apply rules for your enriched data.
If you want some specific data to be published on MQTT, you must add a filter “rule”. A rule has two parts:
●
An
event
, which determines WHEN data will be published;
●
A
payload
, which determines WHAT data will be published.
Enrichment is done before Rules are applied. This means that all Rules created will apply to the
enriched data.
If scaling has been applied for a register during the enrichment process, the Rules you create will apply
to the enriched and scaled data for that register.
If you have not applied enrichment for a register, the Rules you create for that register will apply to
the raw Modbus register data.
