industrial//industrial data layer//MQTT in the plant

How MQTT is used on the OT/IT boundary: a PLC or, more often, an edge gateway publishes plant data to a broker, and SCADA, MES, historian, analytics and cloud each subscribe. Telemetry and events, pub/sub on TCP/IP.

How MQTT is used on the OT/IT boundary: a PLC or, more often, an edge gateway publishes plant data to a broker, and SCADA, MES, historian, analytics and cloud each subscribe. Telemetry and events, pub/sub on TCP/IP.

The producer does not need to know its consumers. A new analytics tool is a new subscription, not a new connection to the PLC; that decoupling is what lets a plant add consumers without touching control (publish-subscribe).

Division of labor with the fieldbuses: Modbus, PROFINET and friends read and write devices; MQTT distributes information between systems. A sound architecture is PLC on a fieldbus, gateway in the middle, MQTT toward IT and the cloud. MQTT was never meant to move a robot axis (Modbus).

The topic tree becomes the plant's addressing scheme (factory, line, machine, signal), and with a shared payload convention such as Sparkplug it grows into a unified namespace (data contextualization). Brokers can be on premises, hosted, bridged and redundant; store-and-forward at the gateway covers link outages.