Problem reading MBUS data with Sontex 531

Hello,

I have a heatpump monitor which seems to be running correctly except for the most important bit - the MBUS reader. I measure 29v across the terminals but do not see any inputs in Emoncms created as per the setup guide.

I set the firmware for the Sontex:
#define MBUS_ENABLE 1
#define SONTEX_531

Not sure what the address is so set to scan:
byte mbus_address = 0; // Set to 0 for auto scan, (test: check timeout 10ms)

I have also tried the MBUS reader firmware but have not had any luck with that either (no ACK response to any of the commands I try).

Any help appreciated!

Tagging @TrystanLea as resident expert :slight_smile:

Hello @markb

The issue is probably the baud rate. If you try the MBUS reader with both 2400 and 4800 to see if you get any reply that’s probably the first thing to try: https://github.com/openenergymonitor/HeatpumpMonitor/blob/master/Firmware/Arduino/MBUS_Reader/MBUS_Reader.ino#L50

You can usually find the baud rate and address of the unit from the little display on the Sontex unit itself which might be worth trying just so that you know how it is currently configured.

Thanks Trysten, grabbing it from the display is a useful tip. I can see baud rate set to 2400 and address is set to 0. That made me a bit suspicious (setting address to 0 did not work) and digging deeper I think it may not have m-bus enabled - despite me asking for it.

Will need to follow up with the supplier!

Dragging up my old topic here, I confirmed with Sontex that I have a meter with the M-Bus option installed. I’m now a bit stuck as to why I’m not getting anything from it.

Does anyone have any idea how to troubleshoot this? Use an oscilloscope to check the M-Bus output? Buy (or borrow) a different board that can read M-Bus??

Any help appreciated, would love to get the heatpump monitor up and running.

Hi Mark,

Sorry to here your having Mbus issues. Im looking at purchacing a Sontex heat meter for my system. If you dont mind me asking. Where have you broken into the pipework to install heat meter. Is inside the heatpump or property?

As for trouble shooting sounds like you need to local weather the issue is with the heat meter, cabling or Mbus reader. If I were you I would be a cheap USB to mbus adaptor and try communicating directly to it.

cheers

Gareth

Hi Gareth, my meter is installed in our house before the pipework splits out for the hot water tank, central heating pipes etc.

Good suggestion on the USB dongle - any idea how you read the data from it though?

Hi Mark,

Thanks for that information. I dont currently have a heat meter. I am currently trying to simulate the heat output using calulated values. Would you mind posting a screenshot of a hot water heat up cycle on the my heatpump app please? Also what make is yours?

If you have a spare Pi or computer knocking around you could use node red and this plug in and try and pull some data from it. What have you got your heat meter connected to atm?

Is th Sontex connected to one of these?

Cheers

Gareth

I’m not using the heatpump app at the moment. Do you mean the heat up cycle for the flow from the heat pump? If so, this morning it was this (from probe on the pipework):

I have an LG ThermaV. At the moment the heat meter is still connected to the DIY heatpump monitor kit - as per what you’ve linked to.

Mark

Hi @markb, interested in your experience here and wondered if you’d had any further luck in the past week at all? just ordered a sontex 531 w. mbus myself for the same purpose. Not yet at a stage where ive tried to get an OEM heat pump monitor and Sontex talking but will be in a couple of weeks. Will try getting it to work with a USB adaptor in the meantime out of curiosity.

@thedawnbefore tagging along here! I am also trying to get my sontex 531 connected via the M-Bus to UART Converter and an emonBase.

So far, following the set up guide I’ve only been able to get this limited output, so seemingly some data is getting through but I can’t work out what to do next. My checklist:

  • Wires - all triple checked!
  • Interfacer settings - checked the address and baud rate on the 531 (see page 44 for how to navigate the menu system to get yours)
  • M-Bus to UART Converter - the little red light on the USB interface only came on once and now doesn’t, so I’m wondering if the converter is broken. I’ve ordered a M-Bus to USB Converter as these are now back in stock to see if that makes a difference
2021-11-20 21:38:09,517 INFO     MainThread Setting RFM2Pi calibration: 230V (1p)
2021-11-20 21:38:10,519 INFO     MainThread Creating EmonHubMBUSInterfacer 'MBUS'
2021-11-20 21:38:10,520 DEBUG    MainThread Connecting to MBUS serial: /dev/ttyAMA0 2400
2021-11-20 21:38:10,522 INFO     MainThread Setting MBUS read_interval: 10
2021-11-20 21:38:10,522 INFO     MainThread Setting MBUS nodename: MBUS
2021-11-20 21:38:10,523 INFO     MainThread Setting MBUS validate_checksum: False
2021-11-20 21:38:10,524 INFO     MainThread Setting MBUS meters: {"sontex": {"address": "0", "type": "sontex531"}}
2021-11-20 21:38:10,525 DEBUG    MainThread Setting MBUS pubchannels: ['ToEmonCMS']
2021-11-20 21:38:10,527 INFO     MainThread Setting emoncmsorg senddata: 1
2021-11-20 21:38:10,528 INFO     MainThread Setting emoncmsorg sendstatus: 1
2021-11-20 21:38:17,552 DEBUG    MBUS       Invalid MBUS data received 0 bytes 2009.0 ms
2021-11-20 21:38:19,763 DEBUG    MBUS       Invalid MBUS data received 0 bytes 2009.9 ms
2021-11-20 21:38:19,964 DEBUG    MBUS       Decoded MBUS data: None
2021-11-20 21:38:26,986 DEBUG    MBUS       Invalid MBUS data received 8 bytes 2006.2 ms
2021-11-20 21:38:29,205 DEBUG    MBUS       Invalid MBUS data received 0 bytes 2017.3 ms
2021-11-20 21:38:29,406 DEBUG    MBUS       Decoded MBUS data: None
2021-11-20 21:38:37,030 DEBUG    MBUS       Invalid MBUS data received 8 bytes 2011.0 ms
2021-11-20 21:38:39,236 DEBUG    MBUS       Invalid MBUS data received 0 bytes 2004.4 ms
2021-11-20 21:38:39,436 DEBUG    MBUS       Decoded MBUS data: None
2021-11-20 21:38:46,458 DEBUG    MBUS       Invalid MBUS data received 6 bytes 2008.6 ms
2021-11-20 21:38:48,672 DEBUG    MBUS       Invalid MBUS data received 0 bytes 2011.8 ms
2021-11-20 21:38:48,873 DEBUG    MBUS       Decoded MBUS data: None
2021-11-20 21:38:57,098 DEBUG    MBUS       Invalid MBUS data received 8 bytes 2006.2 ms
2021-11-20 21:38:59,310 DEBUG    MBUS       Invalid MBUS data received 0 bytes 2010.0 ms
2021-11-20 21:38:59,511 DEBUG    MBUS       Decoded MBUS data: None
2021-11-20 21:39:06,533 DEBUG    MBUS       Invalid MBUS data received 8 bytes 2011.2 ms
2021-11-20 21:39:08,739 DEBUG    MBUS       Invalid MBUS data received 0 bytes 2004.8 ms
2021-11-20 21:39:08,945 DEBUG    MBUS       Decoded MBUS data: None
2021-11-20 21:39:17,095 DEBUG    MBUS       Invalid MBUS data received 8 bytes 2011.1 ms
2021-11-20 21:39:19,306 DEBUG    MBUS       Invalid MBUS data received 0 bytes 2009.4 ms

My interfacer:

[[MBUS]]
    Type = EmonHubMBUSInterfacer
    [[[init_settings]]]
        device = /dev/ttyAMA0
        baud = 2400
    [[[runtimesettings]]]
        pubchannels = ToEmonCMS,
        read_interval = 10
        validate_checksum = False
        nodename = MBUS
        [[[[meters]]]]
            [[[[[sontex]]]]]
                address = 0
                type = sontex531

Note: Post edited to reference new scripts for changing meter MBUS addresses:

See post below for the best way to do this:

@knightian do you have the UART to USB board the right way around I think that caught someone out before as the orientation changed between the older UART converter and the newer… feel free to post a pic up here of the converter and I can check

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@TrystanLea Excellent question, I’m not sure! Here’s my set up - can you spot any obvious mistakes? There’s no power light on the converter, which makes me wonder if it is getting enough power from the Pi.

Thanks

Thanks @knightian looks like one of the MBUS cables is connected to ground, you want the terminals closest to the right hand side, see this picture, hopefully that will bring it to life…

1 Like

Thanks @TrystanLea , silly mistake! Sadly still getting an invalid data error, so must be something else. I’ll try your script to change the meter address in the morning. Thanks again for the late night support :owl:

1 Like

I’ve updated my post above to link to a new post on changing meter MBUS addresses for anyone following this trying to work out how to do this. Here’s the link again:

Reading from multiple MBUS meters with the EmonHub MBUS interfacer - #5 by TrystanLea

I’ve gone ahead and purchased an OEM MBUS USB reader, I seem to be stuck at the first hurdle. I’ve copied and pasted the MBUS config into the Emonhub config file as per the guide (here) but it does not appear on the inputs page. This is on a Pi running Emoncms.

Hello @markb was the old UART MBUS reader working ok for you? Is it the same Pi?

Hi Trysten,

The old one (as in, the heatpump monitor) I never had working and it is the same Pi. Should the reader (the new USB one) show up in the inputs page without a valid MBUS signal or does it require that to appear? I made the assumption it would appear without it, so haven’t actually connected it yet!