amsreader-firmware

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Hi...

I'm not sure this is even possible, as i have no deeper knowledge into this topic. The case is, that i bought a Pow-K (Kamstrup) module from amsleser.no. I have fittet it into my Kamstrup OmniPower meter and have supplied the GPK60 and GPK61 keys, but i get no data.

According to my power provider they state that it works with the Smart-Me modules using GPK11 key. the provider does not have access to that part of the Kamstrup software where they can enable that feature.

So my request is, can this software use a GPK11 key to get data?

I propose we first establish whether the meter provides data at all, as there has been cases of meters not having the HAN port open despite the grid company insistance. Does the LED show a blue light flickering for around 1 second every 10 seconds?

Theres a red flash every 2-3 seconds, and the HAN status In the web ui is red.

If there are no blue flashes there is no incoming data. The red flashes indicate the same as the red HAN status. There is a similar case in one of the threads here, the problem turned out to be that the port was not activated after all.

Here: https://github.com/gskjold/AmsToMqttBridge/issues/115

If using a multimeter to test if my meter is sending data, then what should i expect to read? I assume i need to measure between pin 5 and 6.

Correct. Looking into the meter you will measure between pins 5 and 6:

If the meter is open, the voltage on pin 5 will be 3,3V for around 9 seconds, then a data frame (voltage jumping between 0 and 3,3V; on a multimeter you will just see that the voltage is not stable) that lasts for around 1 second. There is one such data frame each 10 seconds.

And is that the same data that a Smart-me module would utilize? or is it another type of data? I Assume data is pushed and not pulled from the meter? is that the same for the smart-me modules?

Data is pushed from the meter, not pulled. The DATA_IN pin (2) is not used. It is only on pin 5 data is delivered from the meter, so the Smart-me module must use the same pin and same data.

So... I hooked up some jump wires to the pins and my multimeter. Used my phone to record a video of the multimeter for 35 seconds.

Result: a steady 3,29v for the whole 35 seconds. Not a single deviation at all.

I assume this means no data is being sent from the meter. And if I used a smart-me module it wouldn't work either, correct?

According to the grid company my meter should be ready for a smart-me module, but it doesn't makes sense to me at all.

So - no data. You seem to have the same situation as the guy in https://github.com/gskjold/AmsToMqttBridge/issues/115

I would contact the grid company and ask them to double check that the HAN port is acivated.

well.. decided to buy a smart-me module for testing... then I can tell the grid company, that even though they say a smart-me module will work, it doesn't (Or probably wont work) They state they don't have access to the feature in the Kamstrup software to enable/disable the HAN port, but a smart-me module works........... without data?

Sounds like an expensive way to prove there is no data. I think the other guy was in contact with Kamstrup directly in some way. Maybe ask him in the other thread?

Well yes it’s the expensive way… So the smart me module was on my doorstep this morning…

And the result really bugs me 😔 plugged it in, joined Wi-Fi, added the gpk11 key and right away it reads data…. So there’s something different with the amstomqttbridge and smart-me module on how they get the data and the gpk keys.

I’d still rather use the pow-k module over the smart-me module, so let me know if It may be possible or if I can take part in some debugging

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Fra: ArnieO @.> Sendt: Wednesday, October 13, 2021 8:27:50 PM Til: gskjold/AmsToMqttBridge @.> Cc: Heine Madsen @.>; Author @.> Emne: Re: [gskjold/AmsToMqttBridge] Request: Support for Danish meters (Omnipower) using GPK11 key (#126)

Sounds like an expensive way to prove there is no data. I think the other guy was in contact with Kamstrup directly in some way. Maybe ask him in the other thread?

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Well, this was surprising. There are around twenty Pow-K boards running in Denmark now, and I have not seen this problem before.

The only idea I can think of is that the meter needs an "enable" signal on an input pin to ensure the meter outputs data. This is not specified for the Kamstrup meters, but is used in the IEC 62056-21 interface standard used in for instance Sweden and Netherlands (see my overview here). Those interfaces have a "Request" input that must be set high from the device in order to get data from the meter.

The Kamstrup meter has one input pin, see this document, which is pin 2 (figure 5):

The document states (page 9) that pin 2 is pulled high inside the meter by an 82k resistor. It also states that the pin is used for "serial communication of data to the meter", which is in most countries not used (disabled in the meter firmware, I assume) - to eliminate the possibility of the user being able to do whatever could be done from this port. This is why I chose to have pin 2 on Pow-K not connected.

Now I can only speculate:

• I assume you are 100% sure that you measured on the correct pins a stable (approx) 3,3V.
• IF the Kamstrup meter needs the input pin to be high to enable HAN port data AND there is an error on that input on your meter (pullup resistor missing or wrong value?) AND the creators of the Smart-me decided to connect this pin to a high signal to be on the safe side THEN pulling pin 2 high on the Pow-K board could resolve the issue, causing the meter to deliver data.

However, pin 2 is specified for maximum voltage of 3,3V, so you cannot connect it to pin 1.

This is what you could do if you're comfortable with trying this and have access to a suitable resistor:

Connect a resistor (I would try 10k, but anything smaller than than 82k should work) between connector pin 2 and 3,3V on the Pow-K board. If you're equipped to solder it in that is fine, just be careful not to short circuit the connector pins, and also do not apply too much heat close to the large capacitor! Like this: If you are not equipped for soldering, try to twist the leads of the resistor in place, and be sure that there is no short circuit to other pins of the connector.

(Note that there is an unfortunate error on the silkscreen of the card: Vcc and GND on the large capacitor are switched.)

Thanks for that really nice and detailed reply! :)

I'm fairly confident in soldering things. Can you possibly link me to a resistor? Just so I order the correct one :)

I would recommend a small kit, like this one: https://elektronik-lavpris.dk/p95985/k-res-e3-modstandssortiment-e3-480-stk/

(I am not familiar with Danish webshops for components, this was just the first one I found on google - there might be others that are better of cheaper, I have no idea. There might also be stores close to you where you can get such stuff.)

Great.. just ordered...

I might have some resistors laying around bit will have to check their values.

I also assume i need to discharge the super-cap before doing anything... any how-to's on that? or should i just leave it unplugged for some time?

Yes, that is the safe and simple way - just leave it unplugged for some time. It will self discharge. If you want to speed up the discharge, connect a (not much smaller than) 100 ohm resistor across the legs of the capacitor. The voltage will in both cases decrease asymptotically, and faster with a resistor.

Will this be sufficient?

Yes that will work. I recommend measuring it with a multimeter to be sure of the value.

In fact you could connect just a wire (no resistance), but in case you make a mistake with the connection it is safer to use a resistor.

I found a 10k ohm, but still no cigar 🤥

Should I try some higher ohm resistor?

That looks good. Still no blue flashing on the LED?

Still no blue flashing, only red flashes and red status in the ui

What makes this strange is that what you reported earlier (multimeter measurement) indicates that there is no data coming from the meter. However, the Smart-me unit works as expected and reads data from the meter.

The blue pin on the LED is directly connected to the incoming data signal, so it will flash providing there is voltage on the board. Which there clearly is - as the ESP8266 is up and running, generates the UI and generates red flashes on the LED.

So let us assume the board does receive data from the meter, and look for potential errors that could prevent the blue LED from flashing. Could you be so kind as to check two points:

1. The pin distance on the LED (D1) is very small, so I take great care to verify after soldering that there is no short circuit between pins. Can you check with ohmmeter the resistance between pin 3 and 4 on the LED? And if you have a good magnifying glass, check if you see any indication of a short circuit between them? The blue pin is pin 4, green is pin 3. If there is a short circuit between those, the signal to the green LED would interfere with the data signal. See below indications of D1 pins 3 and 4.
2. This should not prevent the blue LED from flashing, but is still a point to check: I did have a bad batch of voltage regulators (U1) in the period I made that board - but I did not think I had shipped any board with bad U1. I can see you make good photos: Can you send me a photo showing the marking on U1? The "bad apples" are easy to identify from the marking.

So i tried checking the led... I can't measure any short circuit.... I tried taking some pictures and a video when it's in the meter https://user-images.githubusercontent.com/48906528/137384870-450b283f-cbae-4466-995e-a8fc9d39fc8d.MOV

Just thinking out loud and with minimal knowledge about the meters... could I be that the smart me module gets the data from the meter wirelessly?

And why does it only need one gpk key and the amstomqtt needs two gpk keys?

Regarding the keys: https://github.com/gskjold/AmsToMqttBridge/issues/73#issuecomment-625050664

Just thinking out loud here, could it be that the smart-me module asks the meter for data rather than passively receiving?

@gskjold not sure how to tie this with #73... But... i do recall that i might have read somewhere on the internet, that smart-me works by pull and amstomqttbridge works with push'ed data.

Would i be possible to implement a pull meter to the amstomqttbridge? At first just for a POC (Need to return my smart-me module within 10 days :D )

Quote from the linked comment from #73 : "It seems the key they provided me was for the Smart-Me module. They're looking into getting me the other keys now."

If we are to implement data pull from the meter, I would need to know how to handshake the meter to receive data. If you have found any information related to this, let me know.

Well.. that might be a dead-end :( https://www.ihc-user.dk/forum/forums/topic/7467-kamstrup-elm%C3%A5lere/?do=findComment&comment=58737

A KMP protocol... Will try to reach out to Kamstrup and see if they are willing to hand out some documentation for this protocol.

I think you are better of asking your grid company for the GPK60/61 keys instead, like @mikfoo did.

Referencing this for the future (in case we ever figure out how this works): https://github.com/MTrab/Kamstrup

@ArnieO is the meters RX pin connected on Pow-K at all?