Mystery optical(?) connector

[grumpydoc]

Long shot, not least because I only have a terrible photo of said connector.

I own a house in which the central heating is based on an air-source heat pump. Wouldn't have been my first choice but it came with the building and works well enough that I have no desire to rip it out. I would, however, like to be able to control it remotely.

According to the manual the controller - a Stiebel WPMW 2 - has an optical RS232 interface but other than that I cannot find anything out about it.

Stiebel sell a box which provides a web interface but it is not cheap at £640 (that's trade price, so without VAT, and possibly not sold to individuals). It appears to hook into the bus between the controller and the heat pump itself (interestingly this appear to be a CAN bus) - Googling around there appears to be a small amount of effort into hacking the CAN bus interface and one guy who found the wired RS232 interface on his heat pump (different model to mine though) and wrote some python scripts to interface to it but that's it.

I haven't asked Stiebel but as they have a product that competes with what I would want to do and, AFAICS, have stopped selling the optical cable/converter to hook up to a PC I would be mildly surprised if they told me much of anything useful. I did find a forum post mentioning a price of €180 for the PC interface which is pretty steep.

The first problem is identifying the connector - which is shown in this photo



Has anyone any idea on what the connector might be? Or any experience with these controllers?

I'm reluctant to take apart the working controller - more hassle than I have time for - but they occasionally turn up on eBay at sensible prices so hopefully I can  get one to take apart and look properly at the thing.

[mikeselectricstuff]

Unlikely to be anything standard - probably just a proprietory shaped hole, with a phototransistor/IR LED

[grumpydoc]

Unlikely to be anything standard - probably just a proprietory shaped hole, with a phototransistor/IR LED

Yeah - you just know the set up will provide maximum annoyance.

Presumably it has to be bidirectional, but I'm not sure I see how. I'm more hoping someone on the forum knows something about these units than is able to recognise the connector, if I am honest.

I'm nowhere near the kit at the moment - will get chance for a further look over Xmas.

[abraxa]

The good news:

The bad news: the guy never shared his circuit. However, he did say that his circuit is a copy of http://openv.wikispaces.com/Bauanleitung+LAN-Ethernet and he uses a MAX232 that he connects to IN/OUT so that he can talk to this device via RS232. You could of course also directly attach an FTDI to talk USB. The optical interface is a SFH7221-Z.

Software: He says you can download ComfortSoft 3.5.0 v-52 at http://www.stiebel-eltron.nl/vakpartners/vakinformatie/downloads/comsoft-software/ or  you can use an alternative software from http://www.kromschroeder.de/Downloadbereich.4101.0.html (4.2.0 Rev.1068). Kromschroeder is the manufacturer of the device that Stiebel-Eltron is rebranding.

Summary thread for the protocol: http://www.haustechnikdialog.de/Forum/t/168379/Stiebel-Eltron-WPF-per-Konsole-auslesen-und-Parameter-aendern
Original thread with complete discussion: http://www.haustechnikdialog.de/Forum/t/98046/Defekte-Stiebel-Eltron-WPF-7-mit-Waermepumpenmanager-WPM-II-wiederbeleben-und-einbauen?page=3
Circuit side discussion: https://www.mikrocontroller.net/topic/252033

It's all in German, so if there's a particular part where you have issues translating, let me know.

[grumpydoc]

The good news:

Wow, thanks that is a really good set of pointers.

I can't quite see how the optical interface works from those shots, I suspect all would be clear if I had a spare unit to inspect.

[abraxa]

I can't quite see how the optical interface works from those shots, I suspect all would be clear if I had a spare unit to inspect.

Yeah, it's a real shame the guy didn't publish his circuit. I really, really don't get why he didn't. However, he did post a close-up of the unpopulated PCB that he's using (

) and with the picture above, it should be straightforward to deduce the circuit since we know which parts he's using. My assumption is that the extra parts he's added (diodes) are used to do away with the MAX232 and produce RS232 line levels without the converter IC.

btw, apparently the optical serial interface uses the following settings:

Baud 2400
Data Bits 8
Parity even
Stop Bits 2

[mikeselectricstuff]

Opto part looks a similar package to this
https://www.digikey.co.uk/product-detail/en/marktech-optoelectronics/MTRS6140D/1125-1062-ND/2798928
Or
https://uk.rs-online.com/web/p/reflective-optical-sensors/4550975/

 I'd think probably most likely infrared, and phototransistor rather than photodiode

[grumpydoc]

Opto part looks a similar package to this
https://www.digikey.co.uk/product-detail/en/marktech-optoelectronics/MTRS6140D/1125-1062-ND/2798928
Or
https://uk.rs-online.com/web/p/reflective-optical-sensors/4550975/

 I'd think probably most likely infrared, and phototransistor rather than photodiode

So,.....

How would you make a bidirectional link - where I have (a tiny amount of) experience with optical it has been either network connections where there is one fibre for transmit and one for receive or SPDIF which is, obviously, unidirectional.

I am aware of bidirectional fibres but they are wavelength multiplexed.

Ah-ha! penny drops, electrical connection out to sensor on end of cable at controller, optical only over last mm or so. D'oh

[mikeselectricstuff]

And half-duplex, obviously.

[grumpydoc]

Picked a controller up on eBay for 20€, dead from a "power surge" so maybe fixable but no great loss if not - no idea whether these have a small SMPS or just a capacitive dropper (although the fact that the RS232 is opto isolated might suggest that the circuit is not mains isolated).

[grumpydoc]

My "dead" unit turned up today. Don't know how dead yet as I've had time to take it apart but not to turn it on 

Mike was right, just a hole above an IR diode/phototransistor - the device looks like a SFH 7221

Steibel confirmed they do not sell the cable any more so DIY is the only option. They don't have the software either and, so far, the links above are dead. That probably is no great loss as I'll want to use a Pi or something similar for the interface.

Two board construction. Small linear PSU, 80C32 MPU, 4153 RTC with 0.1F supercap and 81C91 CAN bus controller are the main points of interest.








EDIT: Software is at http://www.kromschroeder.de/heizwaerme/produkte/downloadbereich.html

EDIT2: Just noticed this is a WPM controller, not WPM2; doesn't really matter for this use. It also appears to work - at least the MPU and user interface stuff, remarkably this is after an unfortunate experience with 240V and the CAN bus VCC rail.  . Note to self, when feeding mains into unlabelled PCB which has a LOT of spade connectors to choose from double check that the orientation of the board matches the orientation of the detached rear panel with the labels on

[mzutg]

Hi,

did you have any luck connecting to the board?

Best

[grumpydoc]

Not yet - haven't had any time to look at it.

[fredmoro]

Helloo!

I have a WPL 18 Cool heatpump, with WPM II controller. And I think I could communicate with it, using the optical interface.
I use a raspberry pi, and an IR LED + photodiuode connected to the pi serial uart. The photodiode and the IR LED salvaged from an old ball mouse. The optical elements are too big to fit in the hole, so I used optic fibers to connect them to the wpm ii. Soon will post some photo of it ...

So it semms working - I'm trying to read all the info gathered on this forum, and the links above... Now I can read some response on the serial port, but don't know what they mean...

Do you have any progress?

[amyk]

I wouldn't call that a connector so much as it is a hole with a sensor in it.

[fredmoro]

Hi.

I tested the communication: The messages were just reflections or something ... So I read my own message back in a distorted way. (you probably need some other component in the circuit, like a capacitor or something)
In the meantime, I have found a successor to SFH 7221, which is still available: SFH 7250 https://media.osram.info/media/resource/hires/osram-dam-2496516/SFH%207250.pdf
I think I’ll buy some and continue experimenting with them. This will at least ensure IR compatibility with WPM II

[grumpydoc]

I suppose I really ought to find more time for this project  It's almost 3 years since I started - sadly I have essentially zero time for hobby electronics these days.

As it happens I found a WPMII at a reasonable price on eBay which rekindled interest - rather different board based on a µPD78F1168

Hi.

I tested the communication: The messages were just reflections or something ... So I read my own message back in a distorted way. (you probably need some other component in the circuit, like a capacitor or something)

Yeah, it sounds like there are reflections meaning your phototransistor is picking up output from your IR LED - but none of the other circuits (see below) include anything to suppress "local echoes" so, presumably, if you get the two SHF7221/7250's close enough together and well aligned it is not a problem.

Sadly several of the pages referenced a couple of years ago no longer exist - though the web archive has a partial record, including this page https://web.archive.org/web/20160619033006/http://openv.wikispaces.com/Adapter+Eigenbau. The last but one is probably pretty similar to the hardware previously discussed in this thread but the last one is also interesting - utilising a USB interface but the TTL-level RS232/SFH7221 interface side of things is very simple.

As a starting point I reverse engineered the schematic for the WPM controller I bought (I chose to do that board because the serial I/O is on fixed pins on the 80C32 microcontroller so it was easier to start at those pins).



The red dots are where there are odd vias that I have not been able to trace. They usually start out on a trace on the top of the board but don't connect on the bottom of the board (it is 4-layer) and the ground fill prevents me from seeing if there is a trace going somewhere on an inner layer but it's quite possible that they don't go anywhere - the circuit seems complete without adding anything.

The enable is one of the data outputs from a 74HC4094 serial->parallel shift register, I assume this is just driven by the controller, I haven't bothered tracing it further.

So, next step is to figure out what else I need to buy, apart from a £1 SFH7250, to make minimum order at Mouser

[alyy]

Hey hey grumpydoc, any progress here? 
I am on the very similar project, trying to link WPMW to ESP32 -> wifi -> mqtt server -> remote management.

[geggi1]

Assuming you the inteface is very similar what used on fluke scoopmeters.
You can google "fluke scopemeter optic interface diy"
You can use a USB to serial converter at TTL level and a few additional componets to build the interface.

[grumpydoc]

Hey hey grumpydoc, any progress here? 
I am on the very similar project, trying to link WPMW to ESP32 -> wifi -> mqtt server -> remote management.

Sadly not - mostly because I decided against leaving a connected PC, plus router, Livebox etc running 24/7 when we were not in the house.

[alyy]

I made some progress
Built a crude IR RTX device using SFH 7250, diode, 2 resistors and USB-UART (TTL) cable. It works!
Found original software somewhere deep in the internet archives.
Quite a few curse-words while installing software made in XP & Vista times onto Win10 machine.
But, at the end, I got it up and running! Software connects to the heat pump, reads data and config is possible.
Now I have collected a few samples of communication using a com port sniffer.
Next task is analyze the data and build a small controller board using ESP32 to read statuses, temperatures and select operation modes.
Task a bit further down the line is MQTT or Home-Assistant integration.

[alyy]

If anyone needs more information on this topic, I was able to build a simple optical interface and windows software that reads parameters from the Stiebel Eltron and compatible heat pumps. Tested on WPM2.

My GitHub project

[Clubazur]

Hi alyy,

Great work. I am a pretty good Home Assistant user and I would like to integrate my SE WPM.  Unfortunatly I am on the beginning road to integrate this. First step, can you please give me a clue where to find the ComfortSoft 3.5 Software?
AFAK, all Legacy links are dead now. Plan is to use esphome / MQTT and custom esp32 infrared Interface. Maybe you can help me for this first step.

Thanks

[alyy]

Hi, thanks for interest in my work.
It would be great if you can test my project from the Github. Link is above and here. It has all the essentials of the ComfortSoft in a small package. Also great for diagnosing the cable and connectivity to the WPM control box.
When you get this up and running, I can share my copy of the ComfortSoft together with instructions on how to install it onto the modern Windows machine. It originates from the Win XP era
Do you have WPM or WPM2 control box?
Do you already have the IR cable?

I like your idea to use ESPHome as a bridge between HA and UART port. I am not yet familiar with both of them, so my question is, how and where do you plan to encode and decode data packets for the heat pump? Will that be a custom code in the ESP or in HA? How do you make visuals for such a custom device in HA?

I currently don't have the HA yet, therefore I am running my monitoring software on a tiny PC in the boiler room
Plan is to migrate to HA at some point..

[Clubazur]

Hi alyy,

I don't have an IR cable yet. If you can share a schema, or give me an hint where to buy, would be great. I have to find out first more about the protocol and how "heavy" it is. Plan is to decode this on a ESP32 device (c/arduino on PlatformIO), first step will be a MQTT sensor device for Home Assistant. But first I need the cable. I have an WPF 13 (2003!) running with the IR option in front of the controller.

Thanks.