The MQTT Subscribe block receives messages on topics to which
you have subscribed. When you subscribe to a topic, the Message Queuing Telemetry
Transport (MQTT) broker sends messages to the MQTT Subscribe
block on that topic. The broker is primarily responsible for receiving all messages,
filtering messages, deciding who is interested in the messages, and publishing the
messages to all subscribed clients. This block has two outputs,
rdy and val.Figure 1.
