Gateway between Homematic and MQTT
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owagner * 0.19 - 2016/06/23 - owagner
  - add command/list to get a channel list. Payload is a Java RegEx
pattern, result is returned in "<prefix>/result/list"
Latest commit 4192006 Jun 23, 2016


Written and (C) 2015-16 Oliver Wagner

Provided under the terms of the MIT license.


hm2mqtt is a gateway between a Homematic home automation system and MQTT.

It is intended as a building block in heterogenous smart home environments where an MQTT message broker is used as the centralized message bus. See for a rationale and architectural overview.

hm2mqtt communicates with Homematic using the documented XML-RPC API and thus requires either an CCU1/CCU2 or a Homematic configuration adapter with the XML-RPC service running on a host (currently Windows-only). It is not able to talk directly to Homematic devices using 3rd party hardware like a CUL.


It is possible to run hm2mqtt directly on a CCU2, using the Embedded JRE. Courtesy of hobbyquaker, a CCU2 addon wrapper is available.

Build Status Automatically built jars (and the CCU2 addon) can be downloaded from the release page on GitHub at

Device names and topic structure

hm2mqtt will try to read device and channel names from the specified HM hosts using the ReGa TCL interface on port 8181. If this succeeds, channel names will be resolved into symbolic names before publishing.

The topics generated and accepted are of the form


The function is status for published status reports, set for inbound change requests, get to synchronously and activly request a value from a device, and command to send commands.

The channel is either the raw address or a name resolved by querying the ReGa.

Note that incoming messages are accepted on both the symbolic and the address channel name.

A special topic is prefix/connected. It holds an enum value which denotes whether the adapter is currently running (1) and connected to HM (2). It's set to 0 on disconnect using a MQTT will.

Homematic Data types

Homematic datapoints can have a variety of data types:

  • BOOL
  • ENUM

hm2mqtt needs to know the type of a data point in order to properly encode the outgoing messages. Types are obtained using getParamsetDescription calls when new devices show up, and are cached in the device cache file.

Registering as a link partner

An application (like hm2mqtt) can tell an interface server (rfd/hs485d) that it is activly using a datapoint. This will in turn cause the interface server to register itself as a link partner with the remote device.

This means that everytime the remote device sends a status message, it expects the interface server to acknowledge this (true bidirectional communication), like it does with any other direct link partners.

If the interface server is not linked with the device, it will still receive and process status messages. However, there is no bidirectional communication in that case -- if the interface server does, for any reason (like RF interference), not receive a status message, the remote device will not resend it. This particular behavior is often not well understood.

hm2mqtt will not automatically register itself as a user of a datapoint. You can do this manually by publishing to the bind/unbind command, or e.g. using

MQTT Message format

The message format generated is a JSON encoded object with the following members:

  • val - the actual value, in numeric format
  • ts - timestamp in milliseconds when this message was generated
  • hm_addr - source HM device address and channel number
  • hm_getid - will be set in responses to get requests and contains the payload from the get message
  • hm_unit - has the unit specifier from the ParamsetDescription of the datapoint
  • hm_enum - has the textual enum value from the ParamsetDescription of the datapoint, for ENUM types

Datapoints with type ACTION are sent with the MQTT retain flag set to false, all others with retain set to true. _ACTION_s e.G. are press reports (PRESS_SHORT, PRESS_LONG, PRESS_CONT)


Configuration options can either be specified on the command line, or as system properties with the prefix "hm2mqtt". Examples:

java -jar hm2mqtt.jar

java -jar hm2mqtt.jar

Available options:

  • mqtt.server

    ServerURI of the MQTT broker to connect to. Defaults to "tcp://localhost:1883".

    Two types of connection are supported: tcp:// for a TCP connection and ssl:// for a TCP connection secured by SSL/TLS. For example:


    If the port is not specified, it will default to 1883 for tcp:// URIs, and 8883 for ssl:// URIs.

    Note that using SSL connections requires additional configuration at the JVM level. For example, the broker's certificate needs to be verifiable by the JVM using it's CA cert store.

  • mqtt.clientid

    ClientID to use in the MQTT connection. Defaults to "hm2mqtt".

  • mqtt.topic

    The topic prefix used for publishing and subscribing. Defaults to "hm/". ^

  • mqtt.username

  • mqtt.password

    Optional, username and password for authentication against the broker.


    List of host:port addresses where XML-RPC services are to be connected. If no port is specified, the default ports of 2000 and 2001 will be used (rfd and hm485d on a CCU, respectivly). No default, must be specified.

  • hm.idleTimeout

    When no XML-RPC request has been received for the specified amount of seconds, a XML PING event is initiated. Another XML-RPC init request will be sent to all services after twice the specified timeout. Defaults to 120s.

  • hm.devicecachefile

    Path and filename of the device cache file. Defaults to "hm2mqtt.devcache".

  • hm.localhost

    Local address used when sending init (callback) requests to the XML-RPC server. Default is the result of getHostAddress(). Set this when hm2mqtt has trouble determining your local host's address automatically.

  • hm.bindaddress

    Local address and port used to listen for callback requests. If not specified hm2mqtt will pick a valid local address and a random port

    Example: Listen on all local adresses on port 3333:

  • hm.disableReGa

    Boolean. When set to true, disable all attempts to resolve names via ReGa. Will use channel and device IDs as names, unless hm.jsonNameTable is specified

  • hm.jsonNameTable

    File name. When specified, points to a JSON encoded file which contains channel and device address to name mappings (e.g. generated by hm-manager)

See also


  • 0.19 - 2016/06/23 - owagner

    • add command/list to get a channel list. Payload is a Java RegEx pattern, result is returned in "/result/list"
  • 0.18 - 2016/06/04 - owagner

    • support MQTT authentication. Implements #10.
  • 0.17 - 2016/02/28 - owagner

    • fix topic of published message in response to /get/ requests; previously, the datapoint name was bogusly attached twice
  • 0.16 - 2015/08/12 - owagner

    • retry a xml-rpc request at most once (after a 10s grace period). Previously, would retry requests indefinitely with a 30s delay, which defeated the ping mechanism
  • 0.15 - 2015/07/26 - owagner

    • accept PING reply events (events with address "CENTRAL"), and use "ping" calls as a first-step measure in case of idle timeouts. Re-Init will still be sent after twice the specified timeout value. Change default idle timeout to 120s.
  • 0.14 - 2015/07/25 - owagner

    • new option "hm.jsonNameTable" to specify a file which includes a JSON encoded table with device and channel address to name mappings (e.g. generated by hm-manager)
  • 0.13 - 2015/07/19 - owagner

    • updated to eclipse-paho 1.0.2 and minimal-json 0.9.2
    • ignore intermediate syslog I/O errors
  • 0.12 - 2015/06/11 - owagner

    • generate "ts" and "lc" timestamp fields in published messages
    • no longer automatically register with reportValueUsage
    • add a command channel and bind/unbind commands as an reportValueUsage interface
    • new option "hm.bindaddress"
  • 0.11 - 2015/03/14 - owagner

    • include "hm_unit" and "hm_enum" in published messages, when applicable
  • 0.10 - 2015/03/09 - owagner

    • do not call InetAddress.getLocalHost() when a local host is specified via hm.localhost, as this triggers an exception on the CCU2
  • 0.9 - 2015/03/05 - owagner

    • added syslog handler, which is active by default. Configuration can be overriden using JUL properties.
    • added /get/ function
  • 0.8 - 2015/02/21 - owagner

    • now again prefer HM channels over devices when resolving by name. This got broken with the 0.6 device cache change
  • 0.7 - 2015/02/11 - owagner

    • added new option hm.disableReGa to disable all name lookups via ReGa
  • 0.6 - 2015/01/31 - owagner

    • completely reworked internal device management. Now properly implements the listDevices/newDevices/deleteDevices contract recommended by HM's XML-RPC API, and will store local device information in a file (default: hm2mqtt.devcache)
    • now correctly calls reportValueUsage with count=1 on every channel's datapoint. Note that this may result in a large number of pending configurations if devices weren't previously strongly linked to the XML-RPC server
    • will now attempt to refetch ReGa names every 10 minutes everytime a name fails to resolve. When a ReGa fetch worked once (i.e. a ReGa is known to be present), failed names will always be published with the retain flag set to false, to avoid the unresolved names ending up in the MQTT broker's persistent storage
  • 0.5 - 2015/01/25 - owagner

    • adapted to new mqtt-smarthome topic hierarchies: /status/ for reports, /set/ for setting values
    • prefix/connected is now an enum as suggested by new mqtt-smarthome spec
    • use QoS 0 for published status reports
  • 0.4 - 2015/01/18 - owagner

    • do proper type handling in outgoing requests, as the previous always-string approach failed with boolean datapoints. Will now cache a type per datapoint. Cache is filled on incoming messages. If a type is unknown on outgoing messages, a getParamsetDescription request is made via XMLRPC and all types are learned for the given channel's datapoint.
    • The "retain" strategy is now based on whether a datapoint is of type ACTION or not. ACTIONs are set to not retain, all others are set to retain. When incoming messages are learned, it is not possible to tell from the datapoint whether they are ACTIONs or BOOLs -- in that case, the decision is still made based on the "PRESS_" prefix
  • 0.3 - 2015/01/06 - owagner

    • ensure numeric values are not sent as strings
    • when hm.localhost is specified, do not call InetAddress.getLocalHost(), as this fails when running directly on the CCU2 and the configured DNS resolver doesn't known the fixed hostname "homematic-ccu2"
  • 0.2 - 2015/01/02 - owagner

    • converted to Gradle build