Page History

Abstract

The MQTT Sparkplug™ B specification defines a way for subscribing clients (such as MQTT Engine) to notify publishing clients (such as MQTT Transmission) via a STATE message when they are online or offline.

...

• Topic:
  • spBv1.0/STATE/primary_host_id
• Payload:
  • { "online" : true,  "timestamp" : 1668114759262}
  • { "online" : false, "timestamp" : 1668114759262}

MQTT Engine compliance

From release 4.0.14 MQTT Engine will support the new STATE message format and be in compliance with MQTT Sparkplug™ B specification v3.0.0.

However as there will still be many existing clients which are only compatible with the MQTT Sparkplug™ B specification v2.2, we have made changes to MQTT Engine to establish a MQTT client whose only function to publish the STATE message in its legacy format. This is a configurable option and will be enabled as default.

How does this change in MQTT Engine affect me?

For most customer this change will be seamless and no additional configuration is required.

...

TahuClient    10Nov2022 17:13:31    ME-LS-6a6595d1-d44b-4: MQTT Client connected to tcp://localhost:1883 on thread Thread-2043
TahuClient    10Nov2022 17:13:31    ME-6ME-88477f61-7893-49b1: MQTT Client connected to tcp://localhost:1883 on thread Thread-2040

How do I configure or disable the legacy state message?

The additional legacy STATE client is configured under the Advanced section for each of the configured MQTT servers in MQTT Engine **** add link *** however for most customers there is no additional configuration required.

...

To disable, you simply deselect the Enable Legacy STATE messages option.