CL-200 Series User Manual Version 1.2.0 Apr. 2019
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3.5 MQTT
MQTT stands for MQ Telemetry Transport, it is a publish/subscribe, extremely simple
and lightweight messaging protocol, designed for constrained devices and
low-bandwidth, high-latency or unreliable networks.
The Publish-Subscribe messaging pattern requires a message broker. The broker is
responsible for distributing messages to interested clients based on the topic of a
message. Now the MQTT Version 3.1.1 becomes an OASIS standard, it is an ideal
protocol
for
communicating
with
connected
devices
in
the
emerging
"machine-to-machine" (M2M) and "Internet of Things" applications, and for mobile
applications where bandwidth and battery power are at a premium.
Input the IP address and port number for the MQTT broker and click on the
Update
Settings
button to save the parameters.
The MQTT Last Will and Testament (LWT) feature is used to notify other clients about
an ungracefully disconnected client. A CL-200-E can register an offline message (LWT)
to the broker. The LWT message will be deliver to all clients who subscribe to the offline
topic if the CL-200-E disconnects unexpectedly.
