Configure a group connection as an MQTT Subscriber

Add a group connection to your MQTT Broker data source hierarchy

1. Select the MQTT Broker connection, right-click it, and then select Add MQTTGroup Connection on the shortcut menu.

   A new MQTT group connection is created in the hierarchy tree and is named New_MQTTGroup_000 by default. Rename it, if desired.

   The New_MQTTGroup_000 Parameters configuration view (right pane) is displayed.

   

2. The Device Group Name field is automatically filled in and cannot be edited. The Device Group Name is used for accessing MQTT data from a DDE/SuiteLink client.

3. Select a level of Quality of Service (QoS) from the drop-down list. The QoS level determines message delivery parameters, with 0 as the lowest level of service, and 2 as the highest level.

   • 0 - At Most Once: The message will be delivered no more than one time, meaning that it may not be delivered. There is no backup of the message, and if the connection to the client is lost, the message will not be delivered. No delivery acknowledgment is provided.

   • 1 - At Least Once: The message will be delivered at least one time, but it may be delivered more than once if the sender does not receive an acknowledgment of successful transmission. The sender stores the message until a receipt acknowledgment is received.

   • 2 - Exactly Once: The message is delivered one time only. The sender stores the message until it receives confirmation of receipt. This is the safest and slowest message transfer mode.

   Note: If the MQTT publisher has a different QoS than the configured QoS, the configured QoS is used.