And if I would buy that “wonder cable”, would I be able to understand the protocol? I didn’t want to risk the chance of buying that expensive cable and not coming any further than using Recom, so i stopped thinking about it. Untill last week.

I started roaming the Internet for more information; I read about “it” being a null modem cable; I looked at the PCB and saw the RJ-11 connector for the Remeha cable was labeled RS-232; I took a long cable with a RJ-11 plug and stuck it into the connector and started measuring with a voltmeter; I saw the outer 2 were 5V and the other GND; that leaves the inner 2 for the serial part. I started thinking about what this super duper Remeha cable could hide inside to make serial communication work? There has to be something special to it… converting TTL to RS-232 perhaps? Why not give it a try…

I have a MAX3232CPE laying around for some time; so I planted it on a breadboard, added some 0.1 μF capacitors and built this schema I found (click it):

Here’s the result:

TTL <--> RS232

Guess what… it works!! My Remeha Calenta was recognized immediately and I watched the data arriving in Recom:

Remeha Recom v4.1.1

With no more than 8 Euros I created my own interface cable; too ridiculous… Special cable?  My A!@&%#%^!!!

OK, but this was just the beginning. With a serial port sniffer i saw the Calenta being queried and I started recognizing the flow temperature, return temperature etc. in the responses that came back from the Calenta. These packets look like this:

02 01 FE 06 48 02 01 F0 14 AA 14 00 80 00 80 86 F3 00 80 B7 10 

00 80 40 1F 70 17 00 80 00 00 00 00 00 BC 02 00 00 00 00 64 00 

00 00 00 C2 0B 10 00 FF FF 00 00 00 00 FF FF 17 00 BC 02 00 00 

00 00 00 00 00 00 00 00 00 C5 9B 03

After an hour or so, i knew where to find some temperature values and stuff like that. The F0 14 marked in red for example, means 53.60 degrees Celsius. That was easy… not good enough for a quiz But I also saw on the amount of values Recom could produce from the incoming bytes, some things had to be stored in bits; the on/off, yes/no, open/closed values appeared not to be stored in a byte, but ‘hidden’ somewhere in a bit maybe? Hmm, how do I know exactly when the Gas valve opens or closes, so how I can locate the bit for that? If it is stored in a bit? This could become a bit more challenging and time consuming than I would like.

Aha! There’s a config directory belonging to the Recom software package, containing XML files; one of them was named exactly like the model that Recom detected. Let’s have a look inside that file… Bingo! These XML files contain very detailed information; they tell me that I can find that Gas valve value in bit 0 of byte 38… Yeeha!

Now it’s just a matter of finding out some more about the leading and trailing bytes and I can start creating my own Remeha Calenta interface to my Domotica system.

Finally I’ll know what the Gas is being used for: DHW or heating. And when the water pressure drops below a value I find alarming, I can be warned before it’s too late. And I can see how much power is actually being produced; and …

Update: RJ-11 is incorrect; it’s a 4P4C connector!

I told him the whole story from the beginning; the phone calls i made with Remeha in April this year to be sure that what i wanted would work, the problems i encountered, the emails to Remeha sales support about the problems, more phonecalls and not getting any answer from Remeha for more than 5 weeks now.

The bottom line is that Remeha is to busy with new developments to pay any attention to what problems i might be experiencing with this very rare combination of their hardware. Simply a matter of costs.  Investing time/money into this matter costs more then and the relevance of the problem is very low for Remeha.

So basically the answer i got today was: “we’re sorry”. Ok. Bad answer for me; i’m not happy with it. But in a way, i can understand it. But this was the first time i was talking to a Remeha person who had the guts to say it out loud… it hurt (a bit), but this is 10 times better than getting no answer at all. That’s really irritating and disrespectful; ever heard of after-sales? The Remeha employee apologized for that.

And before i metioned anything about it, I was told i could return the Gateway and defective Celcia without any problem and i would get my money back. Case closed… regarding doing it the Remeha-way i mean : I’m already one step further in accomplishing what i want another way…

Apparently my list of problems i encountered and that was sent to Remeha by email some time ago has been found again. Remeha’s development department conclusion was that the Gateway must be broken. The Gateway will be replaced in the next couple of days and i hope i’ll get better results then!

Remeha Calenta

It has been a while ago since i worked on this project. After the new central heating had been installed in the first week of april, i spent time to get the combination of Remeha Calenta, Remeha Gateway and Remeha Celcia 20 to work. I failed…

Somewhere there is an unstable factor in this combination that makes these 3 devices not work together as they should, and as was stated that they could by a Remeha technician. So i put this project on hold for a while. But now that holidays have started, and the days will get shorter in a matter of weeks, i would like to have this project finished by the time  we need the central heating again…

Last week i talked to the  person who installed the Calenta and he asked me to write down all my problems in an email that he would forward to Remeha Technical Services department, to see if it was possible to have a Remeha technician coming over to my house to investigate the problems i am having.

After integrating lights, appliances, garage doors, alarm systems, TV, Home theatre, music, the largest piece of equipment that is not yet integrated is the central heating. That has to change… one way or the other!

All kinds of things are made possible these days in this area, just look at the Danfoss Z-Wave controlled radiator thermostats for example. It’s a sign you can’t ignore. So i hope Remeha has a clue of what is going on in terms of Domotica & HVAC; and i hope they inderstand that the systems they produce can no longer be isolated from the rest; it’s time to connect!