Add MQTT Publisher

Configure a MQTT Publisher to publish messages to MQTT Broker defined Topic. Any MQTT client subscribed to that Topic receives the messages.
TIP:
The publisher only supports scalar variables. Arrays, UDTs, and other non-scalar variables are not supported.
  1. In Project view, right-click
    MQTT
    , select
    New
    , and select
    MQTT Publisher
    .
  2. In , configure the following properties:
    Sampling mode
    • None
      .automatic recording is disabled, can record by invoking the Sample method;
    • Periodic
      . at regular intervals records the values of all the selected variables;
    • Change in value
      . at regular intervals records only the values of the selected variables that have changed with respect to the previous sampling.
    Sampling period
    Interval in hours, with millisecond precision, between one sampling and the next, in the Periodic mode.
    Pooling time
    Interval in hours, with millisecond precision, between one sampling and the next, in the Value change mode.
    Folder
    This folder contains variables whose values will be sent to the broker. The Folder node must be a global object and cannot be a session-based object.
    Topic
    Defines MQTT topic on which we are sending/publishing data. (Topic is required. Once topic is empty Publisher will generate warrning message during first publish. RT will not stop and other mqtt functions will keep working, only this specific Publisher will be stopped.)
    QoS
    MQTT Quality of Service (QoS), defines the guarantee of delivery for a specific message (0, 1, 2).
    0 - At most once (May lose messages).
    1 - At least once (Guarantees the message delivery but potentially duplicate messages).
    2 - Exactly once (Ensures messages are delivered exactly once without duplication).
    Retain
    Retain message on the topic even after read
    • True - Enables Retain functionality
    • False - Disables Retain functionality
In
Project view
, in the
MQTT
 folder, the
MQTT Publisher
 object appears.
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