Janz Tec MQTT library for CODESYS SL Article no. 2312000002
MQTT is a Client Server publish/subscribe messaging transport protocol. It is light weight, open, simple, and designed so as to be easy to implement. These characteristics make it ideal for use in many situations, including constrained environments such as communication in Machine to Machine (M2M) and Internet of Things (IoT) contexts where a small code footprint is required and / or network bandwidth is limited.

Janz Tec developed a CODESYS library which implements the MQTT protocol. This way users can add the MQTT protocol easily to their own IEC 61131 applications. The Janz Tec MQTT library for CODESYS implements client functionality. It is completely written in IEC code which guarantees the library can be used on any type of target system.
Features:

CODESYS client library implementing MQTT protocol (version 3.1.1)

MQTT client functionality

Library completely written in IEC code, therefore independent from target system

Publish: Payload of any type can be transmitted to a broker*

Subscribe: Messages of any type from MQTT brokers can be received*

Message classification via MQTT topics

MQTT-QoS-Levels: * QoS0 (At-most-once) * QoS1 (At-least-once)

Authentication with user name / password

Auto-Reconnect is available if connection has been aborted

Channel encryption via SSL (TLS v1.1 Client)

Last will functionality

Topic wildcards (+/#)

For maximum supported message payload size, see global variable MQTT_GVL.MAX_PAYLOAD_SIZE

Currently not supported: * QoS2 (Exactly once)