Updated 10 June 2020

It may be that the Kaifa meter requires more power than the M-Bus Master Hat can drive - in which case you’d need an M-Bus Master which can provide more power. The M-Bus Master hat provides 3 “unit loads” (ULs), which is 4.5mA provided over the bus. The Kaifa specs suggest it may draw up to 50mA (>30 ULs). However, people have reported getting the Kaifa working, so it may be that this is irrelevant, and that it is the polarity which is important to get right (see below).

Updated 28 August 2020

Now pointing at upstream version of AMS Han Decoder repo, which has KFM_001 support merged in.

Updated 16 May 2021

I’ve had a report that the Kaifa MA304 does work with the M-Bus Master Hat, but the M-Bus connection of the meter is polarised - meaning that you must connect the cables to the Hat the correct way around. I’ve been told that the brown wire should be connected to the terminal furthest from the Pi pin header (next to the red LED), and the black/white cable closest to the Pi pin header (next to the green LED).

Many properties in Norway and Sweden have had Kaifa MA304 smart meters with M-Bus support rolled out to them in recent years. Here’s how to use a Raspberry Pi to read it remotely.

You will need:

An M-Bus Master like the M-Bus Master Hat.
The AMS Han Decoder software.
A Raspberry Pi (any model with a 40 pin GPIO header will do).
An ethernet cable (CAT-5 is fine).

Note there are different variants of the MA304 - some support M-Bus, some use standard serial. This article is relevant to M-Bus ones.

Follow these instructions at your own risk, and in particular steer clear of any mains voltage cables!

Instructions

Installing the M-Bus Master

Connect the M-Bus Master to your Pi. To use the M-Bus Master Hat follow the following sections from the instructions here:

Installation
Powering On
Enabling Serial Access
Enable M-Bus

You will need to repeat the “Enable M-Bus” instructions after a reboot of the Pi to enable the M-Bus power:

gpio write 25 1

If red LED of the M-Bus Master Hat is lit you’re ready to continue.

Connect to your Kaifa M-Bus Meter

Take your ethernet cable and cut one of the ends off.

Strip the white/brown and brown cables and insert into your M-Bus Master. Connect the brown cable to the terminal next to the red LED, and the white/brown to the terminal next to the green LED. Take care to use the correct colours - these should be connected to pins 7 & 8 of the remaining RJ-45 plug.

Connect the remaining RJ-45 plug into your Kaifa MA304 meter’s RJ-45 socket - you may have to lift a flap labelled M-Bus to access the socket.

Install Software to Read the Meter

Tun these commands on your Pi (installed with Raspbian):

sudo apt install libjson-perl
sudo apt install libdigest-crc-perl
wget https://raw.githubusercontent.com/robinsmidsrod/ams-han-decoder/master/ams_han_decoder.pl
chmod +x ams_han_decoder.pl

Read the Meter

If using the M-Bus Master Hat make sure the red LED is lit:

gpio write 25 1

Then run:

./ams_han_decoder.pl -m KFM_001 /dev/ttyAMA0

The Kaifa MA304 reports:

The active (instantaneous) power every 2 seconds
Much more comprehensive (instantaneous) information every 10 seconds
Cumulative power usage information every hour, in addition to the 10s information

Sample Output

The software was tested on a Kaifa MA304H4D, and provided the following output:

{
   "data" : {
      "energy_active_cum_export" : {
         "description" : "Cumulative hourly active export energy (A-) (Q2+Q3)",
         "obis_code" : "1-0:2.8.0.255",
         "unit" : "kWh",
         "value" : 2853.145
      },
      "energy_active_cum_import" : {
         "description" : "Cumulative hourly active import energy (A+) (Q1+Q4)",
         "obis_code" : "1-0:1.8.0.255",
         "unit" : "kWh",
         "value" : 11589.514
      },
      "energy_reactive_cum_export" : {
         "description" : "Cumulative hourly reactive export energy (R-) (Q3+Q4)",
         "obis_code" : "1-0:4.8.0.255",
         "unit" : "kVArh",
         "value" : 4285.508
      },
      "energy_reactive_cum_import" : {
         "description" : "Cumulative hourly reactive import energy (R+) (Q1+Q2)",
         "obis_code" : "1-0:3.8.0.255",
         "unit" : "kVArh",
         "value" : 120.588
      },
      "meter_id" : {
         "description" : "Meter ID (GIAI GS1)",
         "obis_code" : "0-0:96.1.0.255",
         "value" : "!!!!REDACTED!!!!"
      },
      "meter_timestamp" : {
         "description" : "Meter timestamp",
         "obis_code" : "0-0:1.0.0.255",
         "value" : "2020-04-02 12:39:00,255 -32768 (0)"
      },
      "meter_type" : {
         "description" : "Meter type",
         "obis_code" : "0-0:96.1.7.255",
         "value" : "MA304H4D"
      },
      "obis_version" : {
         "description" : "OBIS list version identifier",
         "obis_code" : "1-1:0.2.129.255",
         "value" : "KFM_001"
      },
      "phase_current_l1" : {
         "description" : "IL1 Current phase L1",
         "obis_code" : "1-0:31.7.0.255",
         "unit" : "A",
         "value" : 1.661
      },
      "phase_current_l2" : {
         "description" : "IL2 Current phase L2",
         "obis_code" : "1-0:51.7.0.255",
         "unit" : "A",
         "value" : 2.103
      },
      "phase_current_l3" : {
         "description" : "IL3 Current phase L3",
         "obis_code" : "1-0:71.7.0.255",
         "unit" : "A",
         "value" : 1.337
      },
      "phase_voltage_l1" : {
         "description" : "UL1 Phase voltage 4W meter, line voltage 3W meter",
         "obis_code" : "1-0:32.7.0.255",
         "unit" : "V",
         "value" : 228.9
      },
      "phase_voltage_l2" : {
         "description" : "UL2 Phase voltage 4W meter, line voltage 3W meter",
         "obis_code" : "1-0:52.7.0.255",
         "unit" : "V",
         "value" : 228.8
      },
      "phase_voltage_l3" : {
         "description" : "UL3 Phase voltage 4W meter, line voltage 3W meter",
         "obis_code" : "1-0:72.7.0.255",
         "unit" : "V",
         "value" : 227.7
      },
      "power_active_export" : {
         "description" : "Active power export (Q2+Q3)",
         "obis_code" : "1-0:2.7.0.255",
         "unit" : "W",
         "value" : 721
      },
      "power_active_import" : {
         "description" : "Active power import (Q1+Q4)",
         "obis_code" : "1-0:1.7.0.255",
         "unit" : "W",
         "value" : 0
      },
      "power_reactive_export" : {
         "description" : "Reactive power export (Q3+Q4)",
         "obis_code" : "1-0:4.7.0.255",
         "unit" : "VAr",
         "value" : 195
      },
      "power_reactive_import" : {
         "description" : "Reactive power import (Q1+Q2)",
         "obis_code" : "1-0:3.7.0.255",
         "unit" : "VAr",
         "value" : 0
      }
   },
   "header" : {
      "apdu_invoke_id_and_priority" : "40000000",
      "apdu_tag" : "0f",
      "hdlc_addr_client" : "01",
      "hdlc_addr_server" : "0001",
      "hdlc_control" : "10",
      "hdlc_fcs" : "4f07",
      "hdlc_frame_format" : "a09b",
      "hdlc_hcs" : "561b",
      "hdlc_length" : 155,
      "hdlc_segmentation" : 1,
      "hdlc_type" : 11,
      "llc_control" : "00",
      "llc_dst_svc_ap" : "e6",
      "llc_src_svc_ap" : "e7"
   },
   "payload" : [
      "\u0007ä\u0004\u0002\u0004\f'\u0000ÿ�\u0000\u0000",
      [
         "KFM_001",
         "!!!!REDACTED!!!!",
         "MA304H4D",
         0,
         721,
         0,
         195,
         1661,
         2103,
         1337,
         2289,
         2288,
         2277,
         "\u0007ä\u0004\u0002\u0004\f'\u0000ÿ�\u0000\u0000",
         11589514,
         2853145,
         120588,
         4285508
      ]
   ]
}

Technical Details

At first glance the Kaifa MA304 claims to support M-Bus. In fact it only support the M-Bus physical layer, master-slave architecture, with a nominal +36V bus, and uses voltage drops to signal from the master to slave, and current draws to communicate from the slave to the master.

For protocol communication the Kaifa MA304 supports the DLMS/COSEM standard instead of the M-Bus data link, application and network layers, over the top of the M-Bus physical layer. This is a standard serial protocol running at 2400,8,N,1 with information encoded according to the DLMS/COSEM specs and OBIS objects (IEC 62056).

The Kaifa MA304 reports serial data when the M-Bus port is powered every 2 seconds, with additional data every 10s and hour. For more details see this document. The wiring diagram for the Kaifa MA304 M-Bus/OBIS port is here.