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WeeWX-MQTTSubscribe

A Weewx service and driver that receives data from multiple MQTT topics.

Currently MQTT payloads of json, keyword (field1=value, field2=value..), and individual (each topic contains a single observation) are supported.

Getting started

Not sure where to start? Read the getting start notes.

Description

Driver

The driver captures the MQTT payload in a separate thread. Then in genLoopPackets, every element in the queue is turned into its own packet.

It is also possible to subscribe to a second topic. The MQTT payload from this topic is put into a separate queue. This queue is processed by the genArchiveRecords to create archive records (simulating hardware generation). With the combination of the two topics/queues, one can have a WeeWX instance gather the data and publish loop and archive data for other instances to receive.

When generating loop packets and the queue becomes empty, the option, wait_before_retry, controls how long before an attempt is made to get data from the queue.

Service

The service can bind to either new loop packets or new archive records. In both cases a separate thread captures the MQTT payload and puts it on a queue. On new packets/records events, the main thread takes the elements from the queue and accumulates them into a single dictionary of data fields. If necessary, the data is converted to the units of the packet/record. The packet/record is then updated with the data.

The elements that are processed from the queue can be controlled by various configuration options. By default, if the MQTT datetime is less than the previous packet's datetime it is ignored. This check can be ignored by setting ignore_start_time to True. It can be controlled more granularly by setting adjust_start_time to the number of seconds prior to the previous packet's datetime is allowed. Also by default, when the MQTT datetime is greater than the packet's datetime, the pocessing of the queue for this packet stops. This check can be ignored by setting ignore_end_time to True. It can be controlled more granularly by setting adjust_end_time to the number of seconds after the packet's datetime is allowed to be processed.

Note: It is rare that MQTTSubscribe should be configured to run as both a service and driver. If you are augmenting an existing driver's data, run MQTTSubscribe as a service. Otherwise, run it as a driver.

Prerequisites

• Python 3.7 or higher
• Paho MQTT Python client

Installing

• To install version 2.x and prior see, Installing and Updating Version 2.X and Earlier.

• To install version 3.x with WeeWX 4.x see, Installing and updating version 3.x with WeeWX 4.x

• To install version 3.x with WeeWX 5.x and later see, Installing MQTTSubscribe

Debugging

See, debugging.

Getting Help

Feel free to open an issue, start a discussion in github, or post on WeeWX google group. When doing so, see Help! Posting to weewx user for information on capturing the log. And yes, capturing the log from WeeWX startup makes debugging much easeier.