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.
