JMRI code to connect to an MQTT broker, to publish and subscribe to the messages for signal masts. Of course, we agree to a standard for the MQTT topics, and since you were not here, we settled on "mast.xxxx" where xxxx is a number starting at zero. This MQTT topic is used as the User Name in a JMRI signal mast. Created as a Virtual Mast with the Aspect used as the payload in the message. And, yes, the device under the real mast needs to be programmed with the same name and code for each of the "aspect" payloads to be implemented. A yellow and red LED'd dwarf signal can not do a "Clear" aspect, so make sure "Clear" is maybe set to yellow for "Approach" as well. Virtual Masts with agreed upon User Names. Comments are for the One Wire Signals on the NeoPixel string (see prior post) Virtual Mast The Jython (or Python) code shown here below, is to attach a Listener to each Signal Mast, and to publish a message