User Tools

Site Tools


mqtt

MQTT protocol

MQTT or Message Queue Telemetry Transport is a protocol focused on applications in M2M (Machine-to-Machine Interaction) and IIoT (Industrial Internet of Things) systems. Information transfer to MQTT is implemented according to the Publisher/Subscriber scheme and occurs through an intermediate server (Broker). The data source (Publisher) sends data to the server (Broker), other systems and devices, being Subscribers, read them from there.

This method of interaction is well suited for event-based messaging, when the devices themselves periodically communicate. In version 4.0 WebHMI has the ability to work in both Broker and Publisher/Subscriber mode, so it can be used as an IoT Edge gateway to integrate the monitoring object into large IoT solutions such as “smart city”, etc., or on the contrary, to receive data from remote devices (sensors) via the Internet, without the need to integrate IP networks.

The setup pages is similar to other connections setup and there is a MQTT tab for specific settings:

In the MQTT tab you set credentials neccessary to connect to the client. If you leave them emty, the client will connect to internal broker.

Please note that for TLS type authentification you''ll have to provide the necessary credentials, which are mandatory and should be put into respective fields.

The internal brokder have to be switch on in the settings menu:

JSON Fetch tool in the WebHMI registers configuration

With this tool you can exract values by its keys from JSON structures read as String right in the WebHMI register configuration.

The usage scheme is as follows:

Let's suppose you have a JSON value received from 7bit AirPoint module:

To extact individual values from this register, you just clone it and then set the checkbox in the new register properties, type in the key needed and select appropriate type for the final value (int, float, string etc.)

Now your registers for individual JSON keys are ready:

mqtt.txt · Last modified: 2023/02/13 15:39 by emozolyak

Donate Powered by PHP Valid HTML5 Valid CSS Driven by DokuWiki