The MQTT Transmission module acts as an Ignition tag to MQTT Sparkplug bridge. It enables listeners to be attached to Ignition tags which then wait for tag values to change. When they do, MQTT Sparkplug messages are generated to publish the data to an MQTT Server. This also allows them to be consumed by MQTT Engine. In addition, MQTT Transmission also listens for commands via MQTT Sparkplug messages which then allows Ignition tag values to be written to remotely.
More information including installation instructions can be found in the links below.