MQTT is a light weight communication protocol that is widely used for IoT applications.

The IoTT Stick currently supports three ways to use MQTT for layout communication:

1. DCC to MQTT 

DCC to MQTT sends decoded DCC commands (incoming from the DCC interface) to an MQTT broker. This is a one-way communication as DCC basically is a one-way protocol. DCC information can then be used to trigger devices with the MQTT environment.  This offers a convenient way to control IoT devices like lamps, relays etc. from your model railroad layout control system.

2. LocoNet over MQTT

LocoNet over MQTT extends LocoNet to the world wide web by providing a bidirectional interface that makes original LocoNet commands available anywhere in the network. You can use it to send LocoNet information to remote CTC panels or from a handheld throttle to the command station.

3. "native" MQTT

This new mode available with version 1.3.1 of the IoTT Stick software provides a "true" MQTT mode, meaning a topic and message structure that is not defined by LocoNet, but by the devices that publish messages.