MQTT inbound item state being updated too often by openHab


New to openHab, I created a new MQTT item with the following definition:

String ParadoxZoneState “Alarm System Zone State [MAP(]” (gGF) {
mqtt="<[home-mqtt:feeds/paradox:state:REGEX(.Zone (open|close).)]"

This entry allows me to see messages coming from my alarm system that contains “Zone close” and “Zone open”. It worked, but it seems that openHab update the state of the item to nothing every 15 seconds even when MQTT broker doesn’t send any message. Here is the output of the event log (the first one is a legit message sent by my alarm system):

2015-12-03 20:16:00 - ParadoxZoneState state updated to close
2015-12-03 20:16:15 - ParadoxZoneState state updated to
2015-12-03 20:16:30 - ParadoxZoneState state updated to
2015-12-03 20:16:45 - ParadoxZoneState state updated to
2015-12-03 20:17:00 - ParadoxZoneState state updated to

Any clue??



OK… I found it!!!

A very weird bug from the alarm system: every 15 seconds, it sends a message with zero bytes in it. Because of that, when I was doing a mosquito_sub -t “feeds/paradox” to see the messages coming, there was nothing shown on the screen pertaining to the null messages. Openhab was receiving them anyway and that was causing the state change to nothing…

Very happy to have found it… I have been searching this for the last 4 days…



Guy, how are you getting the messages from the Paradox into MQTT format? I’ve been looking for a Paradox integration for a long time!

Hello Marius,

To retrieve data from my Paradox system (it is a Digiplex system), I bought a printer module named APR-PRT1 that is no longer available from paradox. It gives an RS232 output with ascii messages for each event going out in the alarm system. They have a replacement part, the PRT3 (


Guy T.

Thanks, using an MG5050 myself, so that won’t work :smile:

Back to the drawing board…


Hello Guy, with this method you can retrieve data from Paradox system, but can you control the state of a zone (alarm\disarm) ?


Hello Francesco,

No, it is not possible to control the alarm system as the connection I have with the Paradox system is a serial interface (only the transmit and ground pin are connected). My Paradox system is a Digiplex with a PRT1 Printer output serial interface from which I get events data.

Personally, I will never get the alarm system managed or controlled through a network hooked to the Internet…



Hello Guy, thanks for the answer.
Personally I’m searching a method for a total and complete integration between OpenHAB and paradox Alarm.
Another story is the security of openHAB published on Internet. For me, this is a must with or without the integration with the alarm system … :smile:


Just thought it worth sharing - I also wanted a more native solution to integrate my Paradox MG5050 to openhab, but eventually got it going with some ‘middleware’.

Essentially a friend wrote a python app using the twisted matrix libraries to eavesdrop the MG5050’s serial line (can’t recall the port name now). Slightly modifying his app for my setup I’m successfully listening in on all zone open/close events as well as arm, disarm, sleep, stay, siren, etc. events. The app publishes to an MQTT broker, to which openhab subscribes. All this runs off a single Raspberry PI 2 next to my alarm panel with a cheap USB->Serial TTL doing the eavesdropping. To activate the alarm I use a hardwired control into one of the PGM inputs [not ideal]. This has been running flawlessly and is being used every day to automate about 90% of my house’s lights [very quick!]. Its also extremely easy to setup. Perhaps he could share if anyone want: @jasonhector

Hi, sure… I’m interested. Can you give me more details ?
Is your solution compatible with Paradox Digiplex Evo or only with Paradox Magellan ?

I’ve been a bit busy with the Paradox IP150 module. See here for an option to link to it, still very much work in progress though.