Initial setup SlimmeLezer

The SlimmeLezer comes preconfigured with ESPHome, so it can added to Home Assistant quite easily.

The best way for setting it up, is to power it via an USB power supply. In some minor cases, when the SlimmeLezer starts broadcasting its own AP ‘slimmelezer’, it may draw a little too much power and can give problems during setup.

When it’s powered up, it broadcasts a wireless network ‘slimmelezer’. Be patience as this can take 20 to 40-ish seconds. Connect to that wireless network with a phone, tablet or laptop. Once connected, a captive portal will show after some seconds (10 seconds on my iPhone SE and 40 seconds on my iPhone 11 Pro). There you select your network and fill in the required password if needed. Note: hidden networks do work, yet needs an extra setting which isn’t set in my precompiled firmware: fast_connect: true).

When it takes too long to show the slash page, got with a browser to the ip-address

Once connected, it will auto discover in Home Assistant, where you can complete the integration.

If it doesn’t appears in the auto discovery, go to Add Integration > ESPHome:

That’s it, you’re all set to use the SlimmeLezer.


  1. HJoe

    i got my SlimmeLezer yesterday, thank you!
    Tried to set it up using the method above, but always got the error that “[E][dsmr:036]: Error: Message larger than buffer”, no matter how i tried to flash or configure it later. I have opened a ticket at ESP Home issue tracker (, but then I realized that it could be hardware related error as well.
    What do you think Marcel? Any suggestions are welcome.

    1. Marcel

      There are two things you can do:
      1) Stick to ESPHome and open an issue on ESPHome’s GitHub (I’m not the creator of the code, I’ve paid a developer to make it 😉 )
      2) Use esp-link, that’s another kind of firmware which spits out all incoming data via telnet. Than use DSMR integration instead of ESPHome. This could also be handy to give the developers some feed of your data to investigate what’s happening.

  2. Hjalmar

    Hi! Connected the slimmelezer to a powerbank and did the initial WiFi setup. It connected to my WiFi, but when I should connect it to the power meter by the cable it will not start (disconnected to powerbank first). The blue WiFi-led is just blinking once shortly when I put in the cable. Also if I connect the powerbank. How will I fix this?

  3. Florian

    I connected the Slimmelezer exactly like you wrote above. It also appears in the integration window however all the entities except IP address, Uptime, and some Wifi stuff write “Unknown”. The only thing I might have done wrong is that I forgot to update Homeassistant to the newest version, I did that right after connecting the Slimmelezer.

  4. Florian

    I just wrote the other comment. Just wanted to say, I tried installing the Slimmelezer using ESPhome and your code. Same thing, but it doesn’t say “invalid string length”, it says “Incomplete or malformed checksum”… No idea what to do. Btw my device is the “Sagemcom T210-D-r”. Thanks for your help!

      1. Florian

        First of all, thank you so much for your quick reply! I can only imagine how much you have to do right now… Unfortunately, the newest firmware doesn’t change anything. I updated it using esphome-flasher. I still get the same message in the debug log:
        [E][dsmr:138]: _�:2�6�$Sa��f�\:����[��*(�����@C�����g�’TM��
        Incomplete or malformed checksum

        No idea what thats supposed to mean…
        Before, I also tried putting in that extra code from PietPetrus, also no change…

  5. milan

    Hi Marcel,

    Ik ben een complete newbie wat betreft home automation. I heb Home Assistant draaien in Virtual Box in Linux Mint en kan verbinding maken met de UI via mijn browser. Nu heb ik gelezen dat vanaf DSMR5 de slimme meter van stroom wordt voorzien. Mijn meter is DSMR4 en mijn vraag is hoe ik op de slimme meter een voeding aansluit. Verder zou ik graag een uitgebreide handleiding willen ontvangen voor de rest van de installatie. Of links naar waar ik meer kan lezen hoe een en ander werkt en hoe te installeren en firmware updaten.
    Ik hoop dat je mij kunt helpen.

    1. Marcel

      De SlimmeLezer heeft aan de ene kant de opening voor de “telefoon” kabel en aan de ander kant een kleine opening waar de micro usb aansluiting zit. Daar sluit je een simpele telefoonlader, of een usb lader met een usb naar micro usb kabel. Alsof je een telefoon oplaad.

      Flashen kan via OTA. Als de meter een maal is aangesloten op je wifi, kan je naar het ip-adres gaan met een webbrowser en daar via OTA een nieuwe firmware uploaden. Als dat niet lukt, kan je ook via USB de firmware uploaden:

      1. Milan

        Oké ik heb ‘m van stroom voorzien maar ik zie niets verschijnen in mijn netwerk. Is 550 mA output van de adapter genoeg stroom of moet een zwaardere adapter gebruiken? Alle apparaten in mijn netwerk hebben als IP-adres. Hoe kan ik het IP-adres van de slimme lezer aanpassen? En moet ik de slimme lezer in home assistant toevoegen? Zo ja, hoe doe ik dat?

        1. Marcel

          Zie je wel een wifi netwerk erbij komen, genaamd ‘slimmelezer’? Jouw wifi gegevens zijn natuurlijk nog niet bekend in de firmware. Dus de eerste stap is om dat te koppelen aan je wifi.
          * Sluit de SlimmeLezer aan, bij voorkeur aan een usb-lader tijdens configuratie
          * De SlimmeLezer gaat na een seconde of 20~30 een wireless netwerk opzetten, genaamd ‘slimmelezer’
          * Maak daarmee verbinding, na een tijdje (10~60 seconde) komt er een captive portal waar je je wifi kan selecteren
          * Na je wifi credentials ingevuld te hebben, zal deze verbinden met je netwerk en stoppen met het broadcasten van ‘slimmelezer’
          Nu zou het klaar moeten zijn voor gebruik. Via je router moet je je ip kunnen vinden, kans is groot dat het ook bereikbaar is via slimmelezer.local (even pingen).

  6. Zsolt

    Dear Marcel,

    I just stumbled upon your little beast when searching for a possible interface device for my SmartMeter. I recently got my solar panels installed, and theoretically my meter has a P1 port (yet to find out if it’s true, since my provider installed a totally unneccessary extra front plate blocking the port, so I have to officially ask them to reveal the port itself).

    I’d love to buy your preassembled device, and saw that they are out of stock at the moment. Is there any chance to sign up for a “back on stock” alert, so I don’t have to come back every day twice to check if you have them again?
    Many many thanks, and keep up the great work you do!!

    Cheers from Hungary!

    1. Marcel

      I used to sell them as backorder… yet those backorders are growing instead of decreasing, therefor I’ve decided to wait until I’ve got them on stock again. Just keep a close watch on my website. You can subscribe for updates 😉

  7. Thw

    Hi Marcel,
    Mijn Slimmer Lezer is not showing gas consumption.
    I have flashed the slimmelezer with the 2.x firmware for my Iskra MT-382 meter.
    Electricity, both consumption and produced, is showing, but not the gas consumption.
    Is this a known issue?

      1. Thw

        Hi Marcel,
        Thanks for the swift reply. Could you be more specific about the period? It’s been up for more then 2 days now and still shows no gasconsumption. Is that normal?

        1. Marcel

          Het kan zijn dat de gasmeter op een andere BUS ID zit, daar kan ik je nu niet mee helpen. Er loopt een change om deze zelf in te kunnen stellen, maar dat is volgens mij ook alleen nog voor DSMR 4 en 5. Ik raad je aan om support te vragen bij Michiel Appelman op zijn GitHub.

          Het enige wat ik je als support kan aanbieden (en aanraden) is om esp-link te gebruiken in plaats van ESPHome. Dat kan je hier downloaden. In de download zit zit alles wat je nodig hebt, de firmware, hoe je het installeert etc. Hoe je esp-link aan je wifi koppelt, staat hier beschreven.

          De SlimmeLezer met esp-link koppel je via Integratie > DSMR aan je Home Assistant door het ip-adres van de SlimmeLezer en poort 23 in te vullen.

  8. Božidar Brozinčević

    Just recieved slimmelezer today!
    I have connected slimme with USB to do initial setup. It does connect to my wifi, and I was able to add it as integration to my HomeAssistant.
    Now when I disconnect it from usb and connect it to power meter with provided cable ( It’s AM550 it doesn’t show up. As I understand, slimme should work without aditional power?
    Any advice?

    1. Marcel

      Hi, yes indeed, it should. However I’ve seen some cases (can count it on 2 hands) that de DSMR 5 doesn’t give enough power. I’ve seen more cases that the port wasn’t enabled. Can you measure on the two outer pins if there’s 5 volt on it?

      1. Božidar Brozinčević

        Well, I didn’t measure power, but I tried to connect it with USB external power.
        I have only ip adress, signal strength and uptime.
        No measurement….
        Any aditional advice? What can I look for

          1. Božidar Brozinčević

            I have tested voltage on cable – 0V on outer 2 pins.
            I have tested cable, cable is OK.
            I fear that port is disabled…

    2. Boštjan

      Božidar, may I ask how old is your AM550 (which year of production?). I have the one from 2020 and it’s not working with Slimmelezer as it uses a different comm protocol as older ones (as one of electricity providers explained me, the Slimmemlezer can only communicate with AM550, which are 2017 or older).

      1. Marcel

        The SlimmeLezer is based on DSMR… If the meter uses another protocol, than we need to find out if we can add support fir that. I’d suggest to open an issue of feature request at ESPHome GitHub.

      2. Božidar Brozinčević

        Don’t know what year production was, I just got it recently (year ago). Ill take a look tommorow when I get home

  9. Didier Rummens

    Hello, same problem as Florian, everything ok but except Ip, SSID, uptime all the other entities are “unknown”…
    Any idea ?
    I’m running HS 2.8.8

          1. Didier

            Hello again,
            I flash with the Firmware: 2021.8.2 (Sep 11 2021, 20:36:43) (slimmelezer-2021.8.2-state_class-and-BE-fix.bin as I live in BE) but still the same problem in HA: value “unknown” and in the log of the Slimmelezer Web Server I see this:
            [E][dsmr:138]: 0-0:96.1.4(202020202020202020202020202020202020202020202020202020202020202020202020202020202020202020202020)
            Invalid string length

            Thanks for your help

          2. Marcel

            That’s really awkward! 0-0:96.1.4 is the P1 version. That should be like (50213) or something like that. I really advice you to use your own esphome add-on and your own config in HA. You can leave this field away and workaround this issue.

  10. Leo

    Hi Marcel!
    I just got the slimmelezer. Thanks for all your hard work!
    Eager to try I fired it up connected to usb-power but not to the meter. I then get it to connect to my wifi and I am able to access the page with all the information (of course empty).
    When I then try to connect it to my meter I can only connect to the slimmelezer AP. It doesn’t seem to want to start up properly. I tried uploading the latest firmware, and it was successful, but it made no difference. It should have sufficient wifi access outside, and my SSID appears in the initial page.

    Could there be an issue with my meter? It is a Sagemcom T211.

    1. Leo

      Never mind me! It does work, it was probably just the signal strength to the wifi that was a bit to bad, but enough to access.

      Moving it out of the box outside solved it and I get proper data 🙂

  11. Sander van den Broek

    Aansluiten ging eenvoudig, integratie met Home Assistant idem. Echter, in HA wordt er geen data getoond. De waarden van alle entiteiten staan op ‘onbekend’. Wat gaat er mis?

      1. Sander van den Broek

        Euh, geen idee. Hoe kan ik erachter komen?

        Meter is 7 jaar geleden geplaatst met de zonnepanelen. Data werd via P1 uitgelezen naar Enelogic.

        1. Marcel

          Ik zal je een mailtje sturen, kan je daarop antwoorden met een foto van de meter. Zal kijken of ik wat meer voor je kan vinden.

  12. Patric Falinder

    I’ve added my SlimmeLezer to Home Assistant Core and it went fine but when I try to add it to the new Energy-function in HA I just get “No matching statistics found”. What do I need to do to be able to get SlimmeLezer working with HA Energy?

    1. Marcel

      Could be you’re using older firmware… Do you built your own firmware within esphome? Did you try the latest firmware on the productpage?

      1. Patric Falinder

        I run the default config. I flashed Firmware: 2021.8.2 from the product page but now I noticed that there was a “state_class fix” which fixed the problem with HA Energy so now I can choose the SlimmeLezer in the Energy config.

        However now I have another problem. At first I could see all the values from the web UI, even after I flashed the first firmware but a day later when I checked everything is blank except Uptime, Wi-Fi Signal, IP Address and Wi-Fi SSID. I just flashed the state_class fix and it fixed the HA problem but the values are still bland.

        I see there is one comment below me with the same problem. I also live in Sweden. Do you know what the problem might be?

  13. Martin Granlund

    My friend and I having trouble getting data to the device from the meter. All fields are blank in the webserver except some basic wifi info, and no errors in the debug.
    We both have a kamstrup omnipower 3 phase meter with a HAN-module (P1) (sweden)
    Have tried all the firmware and double checked that the p1 port is open from the provider.
    I have all the datasheets if you want to check them out, not sure what to do here.

  14. Papaya


    Belgian user here with a Sagemcom T211 (so, tri-phases) managed by ORES. I’m running the SlimmeLezer with firmware 2021.9.1 and have added the fix for Belgium:
    lib_deps: glmnet/Dsmr@0.5
    lib_ignore: glmnet/Dsmr@0.3

    Though, I notice that the voltage (and the power) on phase 2 is never read. The current is working on phase 2 (and varies), but nothing for the power and the voltage.
    For the other phases and the other sensors, it all works fine (except the total consumption which does not take into account the phase 2 as well).

    Is it a firmware problem ? (I did not find anyone reporting such issue) Or an hardware problem ? (but it would be strange if all other sensors are OK)

    But then, like this, I cannot add it into my Home Assistant’s energy board as the results are not consistent.

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