Home

How to Communicate with Evohome

Honeywell Evohome CH/DHW systems utilize a RF protocol called RAMSES II.

Other systems, including non-Honeywell systems, also use this protocol, or a similar/older protocol called the residential network protocol - YMMV.

This wiki's purpose is to document the data structures and protocols of RAMSES II.

Introduction

This is a sequence of packets sent over the RF network:

045  I --- 01:145038 --:------ 01:145038 30C9 018 0008310107FD02076503077D04075C050758
053  I --- 30:082155 --:------ 30:082155 1F09 003 000537
055 RQ --- 07:045960 01:145038 --:------ 10A0 006 0013740003E4
045 RP --- 01:145038 07:045960 --:------ 10A0 006 0013880003E8
045  I --- 12:010740 --:------ 12:010740 0008 002 00BE
045  I --- 04:056057 --:------ 01:145038 3150 002 0326
045  I --- 34:064023 --:------ 34:064023 3120 007 0070B0000000FF

Using easily-obtained, relatively inexpensive hardware, this RF traffic can be harvested for useful information, and there is also means to inject commands into the network.

Packet Structure

The basic packet structure a number of fields separated by spaces:

aaa XX bbb DEVICE_ID DEVICE_ID DEVICE_ID CODE nnn PAYLOAD.....

The three main elements of any packet are:

• the device_ids (e.g. 04:056057, 01:145038) for controllers, TRV, DHW relays, etc.
• the packet type (I, RQ, RP) and code (30C9, 10A0, and 0008)
• the payload (0008310107FD0...)

A detailed descriptions of the packet structure, and each command code is available within this wiki.

Command Reference

The payload decode information shown in each command uses the Python slices syntax i.e. [start:stop] where the first nibble (4 bits) is numbered 0.

Device communication details

This section is intended to describe the messages sent or received by specific types of device.

Serial Devices

There are several 868Mhz USB devices which may be used to interface with an Evohome system:

• Honeywell HGI80 (Note: in order to send messages using this device the specific device ID 18:000730 must be used and hence it is unable to emulate messages from other devices)

• NanoCUL (add list of firmware links)

• In-circuit Signalduino (modified firmware to be published)

• Seeedstudio RFBee (firmware to be published)

• Others?

Acknowledgements

This work builds upon the work by CrazyDiamond, Hydrogenetic and fullTalgoRythm. We're very grateful to them and the many other contributors.

Disclaimer

This documentation has been developed by observing the messages sent between the various Honeywell devices and is not supported or endorsed in any way by Honeywell or Resideo. The use of this information to control or monitor your home heating system is your own responsibility although we not aware of any risk of damage to devices through the use of these commands.