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
    , and select
    New
    MQTT Publisher
    .
  2. In , configure:
    Sampling mode
    • None
       - automatic recording is disabled. You can record by invoking the Sample method
    • Periodic
       - at regular intervals records the values of all selected variables
    • Change in value
      - at regular intervals records only the values of the selected variables that have changed since to the previous sampling.
    Sampling period
    Frequency of logging the variable to the database. An interval in hours, with millisecond precision, between one sampling and the next.
    Polling time
    Frequency of reading/updating the variable from the external or internal source such as a controller, or the
    FactoryTalk Optix
     model. An interval in hours, with millisecond precision, between one polling and the next.
    Data source
    Specify data source:
    • Folder
       - A folder that contains variables whose values will be sent to the broker. The Folder node must be a global object and not a session-based object.
    • Data logger
       - Specifies which data logger set of variables is published.
    Topic
    An MQTT Topic to which the publisher sends messages.
    QoS
    MQTT Quality of Service (QoS), defines the guarantee of delivery for a specific message:
    0
     - At most once (loss of messages is possible).
    1
     - At least once (ensures message delivery with possible duplicate messages).
    2
     - Exactly once (ensures message delivery without duplication).
    Retain
    Enables or disables retaining read messages on the topic.
    Store and Forward
    Store and Forward stores data in case of temporary connection loss to storage. See Store and Forward.
    • SF Enabled
      . Enables or disables Store and Forward.
    • SF Buffer Max Size
      . Maximum number of elements in the buffer, which can be set from 1 to 100000. An element is one entry (row) in a database table.
    • SF Buffer Overwrite
      . When set to
      True
      , overwrites oldest entries with new data when the buffer limit is reached. When set to
      False
      , ignores new data when the buffer limit is reached.
      TIP: The following diagnostic, read-only properties are available:

        SF Buffer usage
        . Displays the current number of elements in the buffer.

        SF Buffer overflow
        . False - indicates that currently upcoming data is handled. True - indicates that the buffer is full and currently upcoming data is ignored.

In
Project view
, in the
MQTT
 folder, the
MQTT Publisher
 object appears.
Provide Feedback
Have questions or feedback about this documentation? Please submit your feedback here.
Normal