finitude 0.1.1

Controls and shows status of Carrier Infinity and Bryant Evolution HVAC systems.

finitude

Finitude decodes the ABCD bus (RS-485) used by Carrier Infinity and Bryant Evolution HVAC systems. It runs two webservers: one serves HVAC /metrics in a format that can be queried by Prometheus, a time series database. Prometheus is a backend for Grafana visualizations/dashboards.

The other webserver is optional. It stores all the WRITE and ACK06 frames seen on the ABCD bus and dumps them as JSON. The functions in analysis.py can then be used to help find meaning in the frames.

Why?

An HVAC system consumes a lot of energy. You might want to know how hard it's working, how often it's running, whether it's running when your windows are open...

Carrier's apps are crappy and they no longer even have a functioning webapp. Plus it's nice to be able to monitor your equipment without relying on connectivity to Carrier's servers.

Carrier's SAM module provides significant information about the modes of the system. But it does not report the state of the system: when heating and cooling are actually operating, the current fan speed, the zones to which the dampers are directing airflow, etc.

How?

To start with, you'll need an RS-485 adapter that can attach to the wires of Carrier's ABCD bus. If you have a Raspberry Pi or some other computer near one of the Carrier devices, you can use a USB RS-485 adapter. If you don't have a nearby computer but you do have Ethernet near one of the Carrier devices, you can use an Ethernet RS-485 bridge.

You can install finitude from PyPI using pip:

pip install finitude

Soon you'll be able to install an image from Docker Hub. But not yet.

Based On

• https://github.com/3tones/brybus -- This is unmaintained since 2014, but it's simple so that's where I started.

• https://github.com/nebulous/infinitude -- This doesn't focus on RS-485; instead it proxies the thermostat's network traffic to/from Carrier's servers and intercepts/modifies the data stream. It also has an RS-485 parser as a sidelight. If it weren't written in Perl I might have started there. Props to nebulous for continuing to support this.

• https://github.com/acd/infinitive -- This is unmaintained since 2018, but the Go code is clear and there is still an active user community. It does focus on RS-485. It doesn't support multi-zone systems and some of its info fields are only populated by legacy heat pumps.