MQTT Client

The “MQTT Client” library allows for linking a CODESYS controller to an MQTT broker. Then messages can be sent and subscribed to based on topics.

The library “MQTT Client” is now part of the product IIoT Libraries SL and is no longer available as single product.

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MQTT Client

MQTT Client

MQTT (Message Queuing Telemetry Transport) is an open-source IoT protocol that allows for the transmission of telemetry data as messages between devices. Device communication always takes place by means of an MQTT broker (e.g. Mosquitto Messages are sent and subscribed to based on topics. A topic corresponds to a path (e.g. device1/temperature). Subscribing to messages is done by specifying a topic filter. Wildcards are also permitted (+ for one level and # for multiple levels). The message format is not fixed, which means that a JSON string or any data structure can be transmitted.

With the “MQTT Client” library, messages can be sent from a CODESYS controller to an MQTT broker, and messages can be subscribed to based on topics.


Programming system

CODESYS Development System V3.5.14.0 or later

Runtime system

CODESYS Control V3.5.14.0 or later

Supported platforms and devices

Note: Use the “Device Reader” project for locating the functions supported by the PLC. The “Device Reader” project is available in the CODESYS Store free of charge.

Additional requirements

MQTT broker (e.g. Mosquitto




Workstation license

Required accessories

CODESYS Security Key for CODESYS <

Version history

Version Release Notes
Release Date

This version fixes a bug for device versions greater than or equal version

  • Improved timeout handling
  • Updated visualization


Min. CODESYS version:

New Features:

  • Licensing without dongle
20.12.2018 Min. CODESYS version: 04.07.2018

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