Industrial MQTT topic design: names, payloads and data contracts
Design a stable telemetry namespace with identity, timestamps, units, quality and schema ownership before connecting dashboards and consumers.
Retained MQTT message
The latest retained application message stored by a broker for a topic and delivered to matching new subscribers under MQTT rules.
A retained value is not a history archive and does not prove that its source remains connected or fresh. Include source time and stale behavior in the payload contract. Retained-message conventions for telemetry should not be assumed safe for commands. Read MQTT topic design and delivery behavior.
See also: MQTT · QoS (MQTT) · Source timestamp
Use the concept: Industrial data connectivity: from register to consumer · Industrial data contract template
In depth
Historian sampling and deadband: budget storage without losing events
Estimate raw historian volume, distinguish acquisition from storage filtering, and validate compression against the signals and events that matter.
Single-pair Ethernet and APL: two wires to the field instrument
How Single-Pair Ethernet and Ethernet-APL bring power and 10 Mbit/s Ethernet to hazardous-area field devices — and what changes in process design.