Setup for ZPA AM375 in ČEZ

[evlo]

I'm trying to setup DLMS push decoding for this electrical meter https://www.zpa.cz/e-shop/elektromery/am375/

some documentation available

https://www.cezdistribuce.cz/file/edee/distribuce/ppnn/20250901/vp_01_13-seznam-poskytovanych-obis-kodu-pro-rozhrani-hanzapojeni-konektoru-rj12-female-pro-seriovy-port-rs485.pdf

basically it does use rj12 with no power on it, and sends data using rs485 on it, every minute

I'm able to get data out of it using rs485 and simple esp32 program that outputs uart to console

0F 00 00 00 03 00 02 02 16 01 01 16 02 02 00 01 00 00 60 01 01 FF 02 09 0A
31 32 33 34 35 36 37 38 39 30 02 02 00 46 00 00 60 03 0A
03 16 01 02 02 00 47 00 00 11 00 00 FF 03 06 00 00 00 00 02 02 00 46 00 01 60 03 0A
FF 03 16 01 02 02 00 46 00 02 60 03 0A
FF 03 16 00 02 02 00 46 00 03 60 03 0A
FF 03 16 01 02 02 00 46 00 04 60 03 0A
FF 03 16 00 02 02 00 01 00 00 60 0E 00 FF 02 09 02 54 32 02 02 00 03 01 00 01 07 00 FF 02 06 00 00 01 69 02 02 00 03 01 00 15 07 00 FF 02 06 00 00 00 0B 02 02 00 03 01 00 29 07 00 FF 02 06 00 00 01 4A 02 02 00 03 01 00 3D 07 00 FF 02 06 00 00 00 14 02 02 00 03 01 00 02 07 00 FF 02 06 00 00 00 00 02 02 00 03 01 00 16 07 00 FF 02 06 00 00 00 00 02 02 00 03 01 00 2A 07 00 FF 02 06 00
00 00 00 02 02 00 03 01 00 3E 07 00 FF 02 06 00 00 00 00 02 02 00 03 01 00 01 08 00 FF 02 06 00 00 51 52 02 02 00 03 01 00 01 08 01 FF 02 06 00 00 21 67 02 02 00 03 01 00 01 08 02 FF 02 06 00 00 2F EA 02 02 00 03 01 00 01 08 03 FF 02 06 00 00 00 00 02 02 00 03 01 00 01 08 04 FF 02 06 00 00 00 00 02 02 00 03 01 00 02 08 00 FF 02 06 00 00 09 03

seems to be dlms as it can be decoded like this
01 00 01 07 00 FF = 1-0:1.7.0255 : 00 00 00 6B = 107 W
...
01 00 01 08 02 FF = 1-0:1.8.2255 : 00 00 56 0C = 22 540 W

02 = integer 06 = 6 bytes long
02 02 00 03 = indicating obis code - value pair - very simplified description - but enough in case of this meter
however it is be to do so in CPP

when I tried to use ASM2MQTT i get no data in telnet when i setup output to as verbose to telnet, it never catches anything.

I did tried different GPIO pins, i did tried disabling and enabling pullup, but never a thing. I do use same rs485 to uart adapter that gives me output i posted above.

When using it with ASM2MQTT, it does not matter whether I set up pullup or not or which gpio pins i set up it RX indicator faintly lights on the adapter and TX always lights up.
With other program RX only correctly blinks every minute.

I tried different rs485 to uart adapters that do use different chips like max13485 and others, but it always behaves same, well with max13485 i once was able to get RX of all '00 00 00' with the seemingly same byte length as above example every minute, but still, i count it as not working.

What am I doing wrong.

I do just connect A and B to the rs485 adapter from the rj11 plug as I currently do not have any 6p6c cable, but again - it does work with simple setup that just outputs uart to get data from meter.

[ArnieO]

Sorry, I don't have much capacity to assist in debugging DIY projects.
But as a general comment, providing stable power to the ESP is the most common issue. I recommend a LARGE low-ESR decoupling capacitor on ESP 3,3V. We use a supercapacitor in our products.
Also, check that your dupont wire connections are solid.

I did a rapid check of your raw data frame using this tool (highly recommended!) that translates DLMS to the more readable XML format: https://www.gurux.fi/GuruxDLMSTranslator
But I get an error message. Maybe the payload isn't complete, or maybe there are bit errors.

Best of luck with further debugging!

[gskjold]

This sort of looks like DLMS, but it does not comply with the standard, so our firmware would not decode this.

0F 00 00 00 03 - Invoke and priority
00 - Timestamp = null
02 02 - Structure with two items
  16 01 - Enum value = 1
  01 16 - Array with 22 items
	02 02 - Structure with two items (Which is not true, the data after this is not formatted correctly)
		00 01 - What is this?  
		00 00 60 01 01 FF - This looks like OBIS code 0.0-96.1.1-255 
		02 - What is this? 
		09 0A 31 32 33 34 35 36 37 38 39 30 - String (0x09) with ten characters (0x0A) "1234567890"
	02 02 00 46 00 00 60 03 0A 03 16 01 
	02 02 00 47 00 00 11 00 00 FF 03 06 00 00 00 00 
	02 02 00 46 00 01 60 03 0A FF 03 16 01 
	02 02 00 46 00 02 60 03 0A FF 03 16 00 
	02 02 00 46 00 03 60 03 0A FF 03 16 01 
	02 02 00 46 00 04 60 03 0A FF 03 16 00 
	02 02 00 01 00 00 60 0E 00 FF 02 09 02 54 32 
	02 02 00 03 01 00 01 07 00 FF 02 06 00 00 01 69 
	02 02 00 03 01 00 15 07 00 FF 02 06 00 00 00 0B 
	02 02 00 03 01 00 29 07 00 FF 02 06 00 00 01 4A 
	02 02 00 03 01 00 3D 07 00 FF 02 06 00 00 00 14 
	02 02 00 03 01 00 02 07 00 FF 02 06 00 00 00 00 
	02 02 00 03 01 00 16 07 00 FF 02 06 00 00 00 00 
	02 02 00 03 01 00 2A 07 00 FF 02 06 00 00 00 00 
	02 02 00 03 01 00 3E 07 00 FF 02 06 00 00 00 00 
	02 02 00 03 01 00 01 08 00 FF 02 06 00 00 51 52 
	02 02 00 03 01 00 01 08 01 FF 02 06 00 00 21 67 
	02 02 00 03 01 00 01 08 02 FF 02 06 00 00 2F EA 
	02 02 00 03 01 00 01 08 03 FF 02 06 00 00 00 00 
	02 02 00 03 01 00 01 08 04 FF 02 06 00 00 00 00 
	02 02 00 03 01 00 02 08 00 FF 02 06 00 00 09 03

[ArnieO]

And as far as I can see it does not match the document linked by @evlo ?
https://www.cezdistribuce.cz/file/edee/distribuce/ppnn/20250901/vp_01_13-seznam-poskytovanych-obis-kodu-pro-rozhrani-hanzapojeni-konektoru-rj12-female-pro-seriovy-port-rs485.pdf

@evlo : Can you contact the grid company and request documentation for the payload?

[evlo]

yes, no response

it does work with https://github.com/latonita/esphome-dlms-cosem

[ArnieO]

it does work with https://github.com/latonita/esphome-dlms-cosem

Good find! This could be what we need to be able to decode your payload - but priority on looking into this will be low, as we do not have a reader for RS485.