Some questions about HomeMatic RS485 system

[mishoboss]

Hi all. Sorry for that I'm writing in English, but my German is not very good

I'm researching the HomeMatic RS485 system (not the wireless) for my new home. I find it really nice and affordable system. However I have some questions about it:

1. What protocol uses the HomeMatic RS485 system? Somewhere I read that it uses "HomeMatic Wired" protocol, which I guess is something proprietary. Where can I read documentation about it? Can I implement it in my custom software?
2. How the modules are programmed? On the International Conrad shop I read that to program the devices it is used a software called "HomeMatic-centre". However Google doesn't know anything about it. Is it free, is it commercial and where and how can I get it?
3. As I understand every module can be programmed individually. For example "set Output 1 to ON when Input 1 is ON" or similar. Is that true or I didn't understood it right?
4. Where stays that logic - in the software on a PC, or in the module itself? Can this logic work without a PC always on?
5. How the Shading module (BLINDSAKTER) knows where to stop? I don't see inputs in the module for end-switches, but I read it has end-switches inputs. Can I bound the module by a digital input to a window sensor, so when a window is opened to not let the roller goes down?
6. Can I acquire current statuses of the modules by a software? And what statuses can I get? Can I get a roller position and a dimmer value, or just ON/OFF statuses?
7. Are there RS485 wired modules for central heating control? Or analog input modules for temperature sensors?
8. I see there is a CCU (home-matic center) module which provides some sort of XML-RPC gateway to the RS485 bus. Can I run this XML-RPC gateway on my x86 Linux machine? Or is there any other Linux software to act like a gateway to the HomeMatic Wired system? I need an easy way to control my system from a 3-rd party software, without using the CCU. I have USB->RS485 dongle, which I would like to use combined with a Atom mini-ITX PC, instead of the HomeMatic CCU.

Thank you in advance for the answers of these questions.

[owagner]

Hi,

1. It's a proprietary protocol which isn't documented. However, a predessor to this protocol called HS485 was documented and it's possible to use this to help decoding HM485 (see http://www.elv-downloads.de/downloads/p ... tokoll.pdf)

2. You need a CCU-1 (the "centre" is probably just a poor translation from the german "Zentrale")

3. and 4. There are two ways of communicating. Either direct (module to module, directly on the RS485 bus) or via the CCU. The options are different in both cases:

Direct: It's not that abstract. The modules have a concept of sensors and actuators, and you can make direct links between the two; however, this is based on a strict role concept. There is a (undocumented) expert mode but it's still pretty much tied to this role concept. It's nothing like the I/O concept in KNX.

The logic for direct links is directly stored on the modules and works without the CCU.

via CCU: You can write programs which react on sensor events, and do whatever you want with the actuators.

5. It has no inputs for end-switches, the control is solely time based. You configure the time taken for a full up and a full down movement and it interpolates the current position and movement. Every so often it does a full calibration run to the end (configurable)

6. Yes, you can. See http://www.homematic.com/index.php?id=156&L=0 - "Teil 4 - Datenpunkte" shows you which items are available per module. The document covers both wired and RF modules.

7. You can use switch actuators to fiddle with the central heating, but there are no temperature sensors (yet). If you use the CCU, you can get temperatures into it via different means (1Wire, for example)

8. There is currently no documented way of doing this. The piece of software you are refering to is called "hs485d" and is currently only available on the CCU. The CCU is a ARM linux box, so you can run the code in an emulator on x86 linux, however, the interface to the RS485 transceiver inside the CCU is apparently NOT a standard TTY device, so this doesn't yet yield usable results.

EQ-3 has announced that they will be providing the RF version of the XML-RPC gateway (called rfd) for x86 in the future, but have not made any announcement regarding the wired daemon.

It is possible to talk to the devices using an USB RS485 transceiver, but this requires low-level hacking of the protocol.

Best Regards,
Olli

[mishoboss]

Thank you for the great answer.

So, the protocol is proprietary, undocumented and the only way of accessing the bus by 3-rd party software is by using CCU-1. That doesn't let me feel good The only good news is that CCU's price has dropped to 200 Euro and is Linux that can be "touched".

How the user make the direct programming of the modules with CCU-1? I have downloaded Homeputer CL Starter (it's free) and as far as I saw there is a way to program the outputs or/and inputs, depending on module type. There is then Compile and Upload buttons (it's in German tough). Can this programming be done via CCU too, or I need Homeputer CL for that? And is there an English version of Homeputer CL?

What is the relationship of HomeMatic with ELV? Who actually produces the modules? Are they completely the same? It seems they both sell the same modules, but ELV sells them cheaper.

I see there is a new module - HMW-IO-12-SW14-DR. It provides 6 analog inputs (0-10V) for sensors. Are there any libraries in CCU-1 to work with these inputs? Can they be used easily, out of the box for some temperature measurement?

Is the CCU-1 web interface in English?

[owagner]

The CCU-1 has a ajaxish web-based user interface called WebUI. This allows to do the basic configuration of the devices, setting up direct links between devices and creating programs to run on the CCU-1, with a step-by-step point and click interface with the possibility to mix in a crude scripting language called HMScript. The WebUI is german-only, as far as I can tell.

If you are interested in the details of the software structure, there is a nice diagram here

Homeputer CL can replace the WebUI part of the CCU (to be precise, the compiled module it creates replaces ReGaHSS). Using it is not a requirement.

Homematic is designed by EQ-3, a company which seems to be part of the ELV group (if you're really interested, search here ). The components are sold by various large german electronic distributors (ELV themselves, Conrad/Voelkner etc.) and also by some shops which specialize on home automation.

I don't think anyone has yet seen the new Wired module, as it's not being delivered yet.

As for the openness: ELV has gradually opened up the interfaces of the CCU-1. Perhaps they'll eventually wisen up and make it a completely open system, which would invalidate the major advantage of KNX. If not, I think there are several efforts underway to reverse-engineer both the RF and the Wired protocol. For example, I used some of the publically available information to build an Atmega644-based RF/Wired bridge which receives RF key pressed and translates them into wired datagrams.

Best Regards,
Olli

[mishoboss]

Thank you for that info. Seems like this technology is not made to leave the German speaking world and become widespread across Europe. That is a shame, because the modules are at the right price, the system is well designed, and this could turn into a KNX killer for the mass market if only they translate the software to English and open the protocol they use.

About the WebUI capability to program, compile and burn/upload into the modules, is it the same technique as Homeputer CL? As far as I understood it, Homeputer CL has a compiler that compiles to the native code and then burn it to the module. Then this programs runs in that module and can work without CCU or Homeputer.

[owagner]

The modules themselve don't run any complex code. It doesn't matter whether they are configured via WebUI or a 3rd party software (in theory, you can use XML-RPC calls to configure direct links as well), the capabilities are always the same.

Homeputer generates a native executable to run on the CCU; this replaces WebUI programs, but not direct links.

[mishoboss]

Thank you for your answer again. Your answers are very helpful to me.

Some questions about the hardware. What are the "must have" components for starting a HA system with HomeMatic Wired? I guess it's the CCU-1, a power block, and termination module.

About the relay modules - does the HMW-IO-12-Sw7-DR (RS485-I/O-Modul 12 Eingänge, 7 Schaltausgänge) can fully replace 3 and a half HMW-LC-SW2-DR modules (RS485-Schaltaktor 2fach)? I need the relay outputs for controlling some not dimmable lights lights, ventilation and central heating with thermo valves.

Can the RS485-Dimmaktor 1fach module dimm 230V LED lights too?

[owagner]

-- You are right about the minimum stuff required. I suggest getting a 3rd party switching PSU instead of the HM one (cheaper and smaller), for example the Meanwell DS15-24 (also available at ELV).

-- The 7fach module has a shared L line, so you can only replace 3 of the HMW-LC-SW2-DR if you're using the same L line for all outputs (note that at least in Germany, it's common that fuses are linked L1 L2 L3 L1 L2 L3 ... using distribution rails, so if you want to switch two devices which are on different fuses next to each other, you're out of luck)

-- the RS485 is a -- sorry, not sure about the english terminology -- start-of-phase cutting dimming actuator, so you can only use it for plain resistive loads or with PSUs which are designed specially to cope with that (like the Osram "Mouse"), so you need to check your LED PSU specs

[mishoboss]

Thanks again.

The English terminology about "start-of-phase cutting dimming" is "Phase-control dimming". I've done some with Arduino a while ago for incandescent light dimming. I hope it's well done here,
because there are a lot of little tweaks for different kind of lights (it's not a linear function). Some LEDs can be dimmed, but this function has to be fitted for them. It's different than incandescent dimming as far as I know.

About the direct programming of the modules, I see in Homeputer that you can make time based control of the outputs and some logic for the inputs. For example in the "Rollladenaktor" you can drive the shader half the way every Monday at 12:00. And for the inputs you can set some CONDITIONAL logic that can also take the states of other inputs of other modules. Is this the program that is compiled and then run on the "Rollladenaktor" module? Or this stays in the Homeputer? Can I make the "Rollladenaktor" module to check for the state of an input of a "12 Eingänge" module every time one of the buttons (UP or DOWN) is pressed? I want to check for an open window and if it's TRUE, then don't run the shades down. And I want this logic to stay in the module itself.

[owagner]

Everything time based or state-checking needs to be done using the CCU (either WebUI or Homeputer or something else).

All you can do via direct links is basically reacting to live keypresses. The modules themselves have no concept of time of day or state outside their own.

To clarify: The dimming actuator is actually the very simple one normally only useful to indascent lamps (it's a Triac which which is switched on with a certain delay on the phase cycle). I've read about people who have converted them to something else, though. Assuming the HM485 variant is similiar to this one http://www.elv-downloads.de/service/man ... 85D_km.pdf it appears that the Atmega produces a variable control voltage using PWM which can probably be used to drive other kind of dimming actuators.