Glossary · MQTT
What is MQTT protocol?
A lightweight publish/subscribe messaging protocol through a broker, ideal for carrying sensor data from remote sites to a server.
A device publishes to a topic such as site1/gen1/voltage and every subscriber to that topic receives it. QoS levels 0, 1 and 2 set the delivery guarantee.
It does not replace Modbus but complements it: Modbus on site, MQTT from site to cloud.
Related terms
- Modbus protocol
- A simple, open industrial protocol dating from 1979: a client asks, servers answer from numbered registers. It runs over RS485 (RTU) or Ethernet (TCP).
- Edge computing
- Processing data close to where it is produced, on site, instead of sending everything to the server: filtering, calculations and local decisions.