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PostPosted: Fri Dec 07, 2018 5:20 pm
by Jack007

Maybe I'm stretching my luck here but I'm having some trouble with my OTGW (from Nodo).

First, my setup looks like this:
EvoHome touch~~~Honeywell R8810A----Nefit EMS-OT Converter---Bosch Easy Control adapter (OT/EMS-iRT)---Nefit EcomLine (boiler)

My original CH system used the Nefit Ecomline in combination with the Moduline thermostat. My goal was to upgrade the CH system to a multi-zone and keep the perk of a modulating (no on/off) boiler.
Multi-zone heating is realized with the EvoHome system, which works really well. The modulating part required some investigation. After some reading I got convinced that the chosen setup would work.
OT "travels" wireless to the R8810A, the Nefit converts OT to EMS and the Bosch converts EMS to iRT which the boiler "understands".
It worked right out of the box. All leds turned green and the house is warm (for several weeks now).

After i got this setup working i focused my attention on the OT communication and ordered a OTGW from Nodo.

First, as per instruction, i connected the OTGW to the R8810A (as Thermostat). Messages appear in the log window, like the "thermostat is connected" and a regular "T90800002 Write-Data Message ID 128: 2". So this looked good.
Then i connect the OTGW to the Nefit (EMS-OT as boiler). A lot of "Error 3" appeared.

After some reading of what to do next I flashed the "diagnose.hex" on the OTGW and performed the nr. 2 and 3 test.
The #2 test showed the expected behavior (like 500 and 1000 microsec. timings). The #3 test did not so good. Timings varied between some microsec. to up to 7500 microsec. Also some errors were reported.
Something seems to go wrong on the boiler side (which probably has something to do with my "double conversion" setup).

Now i'm stuck on how to proceed. Clearly without the OTGW the installation works. With the OTGW it fails.

Any thoughts are appreciated.




PostPosted: Sat Dec 08, 2018 9:21 pm
by hvxl
So the OTGW reports errors. That doesn't necessarily mean the setup is not working. Possibly the Nefit Converter talks multiple protocols. As long as the Opentherm data is getting through, that may not be an issue. The EMS-OT Converter may figure out which protocol to talk when it starts up. If you connected the OTGW while the converter was already powered up, it may be confused. So I suggest to power off everything and then power up the system in the desired configuration (the OTGW before the EMS-OT Converter) , in case you didn't do that yet.

With the diagnose firmware, or the normal firmware in monitor mode, the OTGW is simply passing through the received signals unmodified. The signals only have to conform to the Opentherm levels. Using such a configuration, is your thermostat still able to control your boiler? If so, do the OT messages reported by the OTGW make sense? Then just ignore the errors.

If the setup doesn't work, even in monitor mode, there's an interface mismatch. That is a problem. But the converter is supposed to talk Opentherm, so that would be strange. Of course, it is also possible that the boiler interface of the OTGW is just not working correctly. Have you tested it with a real Opentherm boiler?

You can see in the equipment matrix that other people have a working system with the OTGW connected to an EMS-OT. So I expect it to work, irrespective of what's behind the converter.

By the way, looking at your chain of devices, shouldn't the Bosch Easy Control adapter already be able to talk Opentherm? Why do you need the Nefit Converter at all? It seems like you could skip the conversion to EMS. (Edit: OK, I checked the documentation. It actually converts EMS to OT or iRT, not EMS or OT to iRT.)


PostPosted: Mon Dec 10, 2018 6:59 pm
by Jack007

Thanks for replying.

I followed your advice and experimented with different sequences of powering up the OTGW and the EMS-OT and EMS-irt. No result what so ever.
Since i've got no real OT boiler at hand this can't be investigated further.

Instead i pulled out my scope and did some measurements. This is what i saw on the thermostat terminal:
Thermostat.png (169.46 KiB) Viewed 2422 times

This looks OK, doesn't it. But is to be expected since the thermostat side seems to work.

The boiler side is another story. The scope gave an overload when measuring on the boiler terminal (probe shield on GND) which would mean a voltage of over 20V. It didn't make any difference if both the OT-EMS and EMS-iRT or only the OT-EMS were connected. As expected, no real signal could be measured with nothing connected on the terminal.
With the EMS-OT connected, shouldn't a similar picture as on the thermostat side be expected?

Also i did carry out the diagnostics test #4 (with the loop).

Enter test number: 4
OK1A high-to-low: 12us
OK1A low-to-high: 23us
OK1B high-to-low: ### Error
OK1B low-to-high: ### Error

Is this to be expected? It doesn't say in the troubleshooting guide.
Could there something be a miss with the opto-couplers (it came pre-installed)? How can i tell?




PostPosted: Sat Dec 22, 2018 6:58 pm
by Jack007
Hi All,

Just to report back what happened in the mean time.

I did some more measurements but the error with diagnostics test #4 remained. I contacted Nodo and explained the issue. After some email exchange the OTGW got send back for repairs. As Nodo stated they exchanged the opto-coupler. Today the repaired OTGW arrived and it passed diagnostics test #4.
The OTGW is now connected to my thermostat and boiler (via OT-EMS/EMS-iRT) and works as expected.