Page History

...

• Installing the Java Runtime Environment
• Installing Ignition
• Installing the following MQTT Modules
  • MQTT Distributor
    • v1v2.71.1 or greater X if using Ignition 7.7.Xv1x or 7.8.x
    • v3.1.0 or greater if using Ignition 7.89.X
  • MQTT Engine
    • v1v2.71.3 or greater X if using Ignition 7.7.x or 7.X8.x
    • v1v3.81.3 0 or greater if using Ignition 7.89.X

Overview:

MQTT Engine provides a mechanism for publishing MQTT Messages from an Ignition script.  This can be useful for general messaging outside of Sparkplug.  For example, one may want to interface to another system that uses MQTT.  This method allows arbitrary MQTT messages to be published based on an events that exist in Ignition.

...

Start by opening an Ignition Designer window and double clicking 'Project-> Gateway Event Scripts' from the Project Browser as shown below:Image Modified

Now select 'Tag Change' click the 'new Tag' icon at the bottom of the window shown below.

Image Modified

Set the name of the script and then select a tag path.  In this case we're using an MQTT Engine tag from an emulated device.

Image Modified

Now select the 'Script' tab near the top.  In it, type the following line:

system.cirruslink.engine.publish("Chariot SCADA", "a/b/c", str("hello world").encode(), 0, 0)

Note, the form of the publish method is as follows.  You may need to change the method arguments based on your configuration:

system.cirruslink.engine.publish(String serverName, String mqttTopic, byte[] payload, int qos, boolean retain)

Where:

• serverName: The server name as shown in the MQTT Engine Settings configuration shown below
• mqttTopic: The MQTT Topic to publish on
• payload: The MQTT payload
• qos: The MQTT quality of service to publish on
• retain: Whether or not to set the retain flag in the MQTT message

...

When complete, the script should look something like this.  Now click OK.

Image Modified

Finally, save and publish the project.  At this point every time this tags value, quality, or timestamp changes it will result in a MQTT message being published on topic 'a/b/c' with a payload of 'hello world'.

...