Additional notes

MQTT Last Will and Testament message support

Additional topic ”online” (for raw and JSON measurement formats) and message type ”baseOnline” (for Azure IoT Hub messaging format) has been added on which broker also sends Aranet PRO ”Last Will and Testament” message in case if Aranet PRO MQTT publisher disconnects from the broker. On successful connection Aranet PRO MQTT publisher notifies about the online state, but on graceful or ungraceful disconnect MQTT broker notifies subscribers about the Aranet PRO MQTT publisher’s offline state.

MQTT Last Will and Testament message examples in different messaging formats.

Online notification on successful connect sent by Aranet PRO:

Raw/JSON

• Topic: <rootTopic>/<base serial number>/online
• Payload example: "true"
• Notes: Retained message. String value.

Azure IoT Hub

• Topic: devices/<base serial number>/messages/devicebound/#
• Payload example:

{
    "body": {
        "online": "true"
    },
    "enqueuedTime": "2024-11-4T14:46:30.064Z",
    "properties": {
        "msgType": "baseOnline"
    }
}

• Notes: Retained message. Message can be identified by the "msgType" value "baseOnline".

LWT notification on Aranet PRO disconnection sent by MQTT broker:

Raw/JSON

• Topic: <rootTopic>/<base serial number>/online
• Payload example: "false"
• Notes: Retained message. String value.

Azure IoT Hub

• Topic: devices/<base serial number>/messages/devicebound/#
• Payload example: N/A
• Notes: Only Azure Event Grid broker supports LWT message sending functionality on Aranet PRO MQTT publisher disconnect event (which requires usage of raw or JSON messaging format instead of Azure IoT Hub message format).