Opentherm Gateway Stops working with error 03 at random times

[mcdomoticz]

Hi, I have build the OTGW form nodo shop.

The gateway works fine but sometimes in runs into error 03 situation and the thermostat displays no communication.
It sometimes happens after day’s or sometimes after e few hours when the gateway was started.
When I look at the signal with my oscilloscope then is can see the difference between normal and error situation.
The difference is that in normal operation I see 1 volt data bits in the signal and in the error state it’s almost 0.5 volt data bits.

How can I fix this problem?

[hvxl]

You'll need to provide a lot more information to be able to give any relevant advice. Error 03 normally only means that one single message was deformed. That should not be a big deal, and the thermostat simply requests the message again. When reporting a problem like this, a log showing the issue would be very helpful.

Also, indicating you measured something without revealing where you measured doesn't really provide any useful information. You should normally see a voltage swing of at least 8V on the opentherm line for communication from master to slave. But communication from slave to master happens using different current levels. These should in theory not be visible when measuring the voltage, as you would normally do with an oscilloscope. In practice, you can actually see the signals leak through into the voltage in most cases, but with a much lower amplitude. Maybe that explains the voltage difference you saw. I really can't tell based on the provided information.

[mcdomoticz]

In the documentation I saw that error 03 can occur if a reference voltage is not correct.
So I have now turned the voltage up a bit. And now I it's not running into a error 03 situation for almost a day now.
Now I see error 03 messages 15 per hour and still no communication error on the thermostat.
I have attached two images of the signal measured at the boiler site of the gateway.
These pictures are from the current "no problem" state.
If the problem occurs again I will capature the signal and attach these again.

The logfile when it was in error 03 state looks like this:

Code: Select all

13:36:57.276629  Error 03
13:36:57.961657  T00560000  Read-Data   Remote parameter settings V/H (MsgID=86): 00000000 00000000
13:36:58.291074  Error 03
13:36:58.902528  T00560000  Read-Data   Remote parameter settings V/H (MsgID=86): 00000000 00000000
13:36:59.107565  Error 03
13:43:51.016156  Error 03
13:43:51.621347  T00560000  Read-Data   Remote parameter settings V/H (MsgID=86): 00000000 00000000
13:43:51.910265  Error 03
13:43:52.569606  T00560000  Read-Data   Remote parameter settings V/H (MsgID=86): 00000000 00000000
13:43:52.723669  Error 03
13:43:53.147490  PR: A=OpenTherm Gateway 6.4
13:43:53.503524  T00560000  Read-Data   Remote parameter settings V/H (MsgID=86): 00000000 00000000
13:43:53.733581  Error 03
13:43:54.446035  T00560000  Read-Data   Remote parameter settings V/H (MsgID=86): 00000000 00000000
13:43:54.750219  Error 03
13:43:55.407988  T00560000  Read-Data   Remote parameter settings V/H (MsgID=86): 00000000 00000000
13:43:55.559667  Error 03
13:43:56.347507  T00560000  Read-Data   Remote parameter settings V/H (MsgID=86): 00000000 00000000
13:43:56.577781  Error 03
13:43:57.297169  T00560000  Read-Data   Remote parameter settings V/H (MsgID=86): 00000000 00000000
13:43:57.592076  Error 03
13:43:58.241755  T00560000  Read-Data   Remote parameter settings V/H (MsgID=86): 00000000 00000000
13:43:58.404536  Error 03
13:43:59.180071  T00560000  Read-Data   Remote parameter settings V/H (MsgID=86): 00000000 00000000
13:43:59.422276  Error 03
13:44:00.125112  T00560000  Read-Data   Remote parameter settings V/H (MsgID=86): 00000000 00000000
13:44:00.439916  Error 03
13:44:01.061723  T00560000  Read-Data   Remote parameter settings V/H (MsgID=86): 00000000 00000000
13:44:01.252632  Error 03
13:44:02.012448  T00560000  Read-Data   Remote parameter settings V/H (MsgID=86): 00000000 00000000
13:44:02.269330  Error 03
13:44:02.943457  T00560000  Read-Data   Remote parameter settings V/H (MsgID=86): 00000000 00000000
13:44:03.279748  Error 03
13:44:03.887990  T00560000  Read-Data   Remote parameter settings V/H (MsgID=86): 00000000 00000000
13:44:04.094364  Error 03
13:44:04.827829  T00560000  Read-Data   Remote parameter settings V/H (MsgID=86): 00000000 00000000
13:44:05.109900  Error 03
13:44:05.797473  T00560000  Read-Data   Remote parameter settings V/H (MsgID=86): 00000000 00000000
13:44:06.126400  Error 03
13:44:06.737918  T00560000  Read-Data   Remote parameter settings V/H (MsgID=86): 00000000 00000000
13:44:06.940019  Error 03
13:44:07.141063  OT: 13.40
13:44:07.393805  SC: 13:44/7
13:44:07.431914  PR: G=00
13:44:07.478967  PR: I=11
13:44:07.544699  PR: O=N
13:44:07.588737  PS: 1
13:44:07.631170  00000000/00000000,0.00,00000000/00000000,0.00,0.00,0.00,0/0,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,13.40,0.00,0.00,0,0/0,0/0,0.00,0.00,00000000/00000000,0,0,0,0,0,0,0,0,0,0
13:44:07.956773  Error 03
13:44:08.766206  Error 03
13:44:09.784485  Error 03
13:44:10.798146  Error 03
13:44:11.614953  Error 03
13:44:14.300093  Error 03
13:44:16.182111  Error 03
13:44:18.068766  Error 03
13:44:19.332585  Error 03
13:44:20.142328  Error 03
13:44:21.157035  Error 03
13:44:21.973867  Error 03
13:44:22.988999  Error 03
13:44:24.000920  Error 03
13:44:25.018976  Error 03
13:44:25.830186  Error 03
13:44:26.851566  Error 03
13:44:27.862318  Error 03
13:44:28.678932  Error 03
13:44:29.689597  Error 03
13:44:30.506725  Error 03
13:44:31.519324  Error 03
13:44:32.533315  Error 03
13:44:33.345699  Error 03
13:44:34.368412  Error 03
13:44:35.382139  Error 03
13:44:36.189721  Error 03
13:44:37.141471  OT: 13.40
13:44:37.406227  SC: 13:44/7
13:44:37.438145  PR: G=00
13:44:37.479834  PR: I=11
13:44:37.519516  PR: O=N
13:44:37.561324  PS: 1
13:44:37.604172  00000000/00000000,0.00,00000000/00000000,0.00,0.00,Error 03
13:44:37.639686  0.00,0/0,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,13.40,0.00,0.00,0,0/0,0/0,0.00,0.00,00000000/00000000,0,0,0,0,0,0,0,0,0,0
13:44:38.226234  Error 03
13:50:31.190570  Command: PR=W
13:50:32.388784  Command: PR=L
13:50:54.940409  Error 03
13:50:54.977455  Error 03
13:50:55.015253  Error 03
13:50:55.051193  Error 03
13:50:55.090572  Error 03
13:50:55.125428  Error 03
13:50:55.162353  Error 03
13:50:55.197066  Error 03
13:50:55.227568  Error 03
13:50:55.261342  Error 03
13:50:55.294493  Error 03
13:50:55.329769  Error 03
13:50:55.366680  Error 03
13:50:55.404014  Error 03
13:50:55.447252  Error 03

[hvxl]

The PS=1 command causes logging to stop. You may want to use the "Resume normal logging after a summary report" option introduced in OTmonitor 6.4.

Those are some nice scope pictures. Mine isn't so advanced that I can save screen shots.

It's a bit strange that your baseline in IMAGE1 varies. That looks like the scope is in AC mode, although it says CH1:DC. Or is that just the trigger and does b~ actually mean AC? Anyway, it shows what I mentioned: The signal on the left is the opentherm message from the OTGW to the boiler, that uses voltage levels, with around 8V difference. The signal in the middle is the response from the boiler. The current changes used to convey the message result in small voltage differences. But the voltages are meaningless. The information is in the current.