ICP DAS USA ET-2200 Series, Руководство пользователя

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ET-2200 Series Ethernet I/O Modules
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4.12 MQTT
MQTT is a Client Server Publish/Subscribe messaging transport protocol. It is simple, light-weight,
and open, and is designed to be easy to implement. These characteristics make it ideal for use in
many situations, including constrained environments such as for communication in
Machine-to-Machine (M2M) and Internet of Things (IoT) contexts where a small code footprint is
required and/or network bandwidth is at a premium.
Clicking the MQTT tab will display the MQTT settings page allowing you enable and configure the
MQTT connections for the ET-2200 device, which will be described in more detail below.
MQTT is a protocol consisting of a Publish/Subscribe mechanism where the Client only needs to
know the IP address for the Broker. The Broker then acts as a central location to handle the sending
and receiving of all messages between a Publisher and a Subscriber. The Publisher is the entity that
publishes the topic and message , the Subscriber is the entity that receives the updated messages
from the Broker. When the Publisher updates a message related to a specific-topic, it is transmitted
to the Broker, which will then send the message to all Subscribers that have subscribed to that
particular topic. Neither the Publisher and nor the Subscriber need to know the status of the other.
The following is a schematic diagram of the system. Publishers are similar to various forms of
publishing house, and focus on updating commodities for different topics such as novels,
newspapers, and magazines, etc. Subscribers are similar to consumers, who purchase, or subscribe
to designated commodities in a bookstore (Broker), which presents the latest information that has
been designated by the Subscriber.