Remote communication with a Technische Alternative CMI

Hi All,
I have several sites equipped with UVR1611 and UVR16x2’s. Long ago I would use either fixed IP addresses or DynDNS to contact my (then) BL-Net interface boxes, and later I switched to the CMI and the TA web portal, doing away with the more and more complicated ways of getting direct IP links set up for free, or even getting them refused on satellite links.
I have a bigger project that I would like to do with something like OpenHab (although the project it is bigger than just a home, rather a lot of buildings), and I need a central platform that can read data from various existing systems, among which a few UVR1611’s and UVR16x2’s - i.e. CMI’s.
Do I understand correctly that I would need a direct incoming IP link at every CMI location, like before I started using the TA web portal?
For security reasons I like the outgoing traffic method TA uses. Can anything like this be mimicked or could the TA portal even remain in the loop? - probably not?
I understand that in a home, one would use the LAN and connect directly to the CMI. in a WAN environment using the Internet, a permanently open pair of IP ports for incoming traffic does not appeal much to me.

Any clues?


A half-Dutch German in southern France, writing in English just for “compatibility reasons” :slight_smile:

Dear Johan,

I am using openHAB with CMI’s also. You can use the HTTP-Binding connecting your WebPortal of TA, requesting a JSON and define Items with JSON-Transformation.

The other option would be a VPN connection to all of your locations, which is what I am using as I want to have access to the different LAN’s anyway. I guess, that this is “the way to go”. Setting up the VPN-Connections is not a big deal since providers like i.e. AVM support this “out-of-the-box”.

As I am using the VPN’s, I am connecting openHAB and the CMI’s via Modbus with a Master-to-Master Proxy, providing the best performance and flexibility.

Hope that helps;-)

Hi Softy,

Yes that sounds like two good solutions, and I was looking into the second, using a VPN service.
I need some clarification though regarding the first solution, as far as “requesting a JSON” goes, because I don’t know what that implies.
Does the Modbus Master-to-Master proxy need any intermediate hardware or a on-site box or PC running some part of OpenHab?
Currently I am busy extending one site, that already runs thermal equipment, with extra monitoring of a off-grid PV system through the CMI, which TA normally doesn’t have a solution for.
Two 3rd party sensors (DC current and voltage conversion to pulses per Volt and Amp) should make it possible to calculate a state-of-charge figure via the existing energy meter configuration of TA.

Dear Johan,

TA offers to download a JSON-file since one of their latest Firmware-Upgrades
This document describes howto use this service. You can test it with your browser. As soon as you see the results, you can configure the openHAB http-binding and create items with the parameters you desire.
Nevertheless, the parameters you can retrieve are limited.

The 2nd solution (Modbus Master-toMaster proxy) is custom-made by myself and not documented.
It is a NODEJS-server where you can connect to with multiple masters and exchange the data. In this case 1 master is the openHAB modbus-binding and the CMI. Both read and write to my custom-made Master-toMaster proxy.

This solution runs in production since about 6month now without any problem. It exchanges informations from openHAB Homematic, Wifi-Switches and others, the CMI and visa-versa.

On what machine are you running openHAB?

Dear Johan,

some more informations:

  1. You do not need additional hardware for the Proxy
  2. Regarding your metering for PV systems TA does not really provide proper solutions. I guess your PV-Controller provides an interface(maybe modbus),to retrieve the desired informations. That is what I am using. Nevertheless, there are many 3rd party sensors available to integrate into openHAB directly. Within openHAB you can do more or less any kind of calculations and meters and store that information into databases for Monitoring.


Hi, I have a Steca PowerTarom on that site, which only transmits data via the proprietary Steca Powerline protocol, unless I use their Tarcom logger which is hopelessly obsolete (serial interface). I could either demodulate the Powerline serial data and decode it in real time, or, as I plan, use a set of industry standard voltage and current transducers with pulse outputs. I also have a logger inside the site’s Studer Xth inverter, but that does not see the charge current, and uses a CAN protocol that TA do not want to hear about…

Not a real problem, since this is for development “fun” only, not a client requirement.

Thanks for your hints

Sorry, forgot to answer as to which machine I use: I just recently installed OpenHAB on my Ubuntu 16.04 home PC and plan to start playing with the only local device I have here which is a Netatmo thermostat.

Hi Softy,

just read your post about Modbus Master2Master proxy.
As I encountered the same problems as Johan with CMI, especially writing values from OH to CMI, may I ask you to share some more infos about your solution?


Hi Bernd,

not a problem. I have written a node.js server application which is communicating as a client with both, the CMI and the Openhab server.

The application transfers the data between the Modbus Masters based on the configured multiple UnitIDs(In/Out).
In my case as example:
Homematic HeatingRegulator Temperatures --> CMI/UVR16X2
CMI/UVR16X2 -->HomematicHeating Regulator SET Temperature
CMI/UVR16X2 -->Fritzbox PowerSwitch

If that is interesting to you, please let me know and I can provide more details.


Hi Softy,

highly appreciate your offer.
My systems is a UVR1611 + CMI and OH2 on Raspi3, currently transferring values from CMI to OH by CoE/Tacmi binding. That works quite well.
The problem is the opposite way: Using the Max! thermostats I’m struggling with sending the temperature values to CMI/UVR. As both systems are Modbus masters your solution seems to be an appropriate way.

Thanks in advance

Are you familiar with node.js?

In order to start, you should have node.js and pm2 installed on your Raspi.

I will prepare the source with a description for you.

very basic only. But no worries, started from scratch with openhab a couple of months ago. Now it just runs smoothly…apart from Modbus issues…

Hi softy,

I’m still curious about your solution.
Can you share some more details about the versions of node.js and pm2 needed, in order to do the initial preparations, please?


Hello did you have a look to

HowTo: Connect a Modbus Master to OpenHAB via RestAPI (Example tested with an TA CMI Device)

Hi, yes I did.

The problem I have is to send values from OH to my CMI, which doesn’t work so far (at least with my limitied knowledge).
Help highly appreciated…