wmbusmeters

The program receives and decodes C1 telegrams (using the wireless mbus protocol) to acquire utility meter readings.

OS/Compiler	Status
Linux G++

wmbusmeters version: 0.3
Usage: wmbusmeters {options} (auto | /dev/ttyUSBx)] { [meter_name] [meter_id] [meter_key] }*

Add more meter triplets to listen to more meters.
Add --verbose for detailed debug information.
    --robot for json output.
    --meterfiles to create status files below tmp,
          named /tmp/meter_name, containing the latest reading.
    --oneshot wait for an update from each meter, then quit.

Specifying auto as the device will automatically look for usb
wmbus dongles on /dev/im871a and /dev/amb8465

No meter triplets means listen for telegram traffic and print any id heard.

Builds and runs on GNU/Linux:

make
./build/wmbusmeters /dev/ttyUSB0 MyTapWater 12345678 00112233445566778899AABBCCDDEEFF

wmbusmeters will detect which kind of dongle is connected to /dev/ttyUSB0. It can be either an IMST 871a dongle or an Amber Wireless AMB8465. If you have setup the udev rules below, then you can use auto instead of /dev/ttyUSB0.

Example output: MyTapWater 12345678 6.375 m3 2017-08-31 09:09.08 3.040 m3 DRY(dry 22-31 days)

./build/wmbusmeters --verbose /dev/ttyUSB0 MyTapWater 12345678 00112233445566778899AABBCCDDEEFF

./build/wmbusmeters --robot auto 12345678 00112233445566778899AABBCCDDEEFF

Robot output: {"name":"MyTapWater","id":"12345678","total_m3":6.375,"target_m3":3.040,"current_status":"","time_dry":"22-31 days","time_reversed":"","time_leaking":"","time_bursting":"","timestamp":"2017-08-31T09:07:18Z"}

You can use --debug to get both verbose output and the actual data bytes sent back and forth with the wmbus usb dongle.

make HOST=arm

Binary generated: ./build_arm/wmbusmeters

make DEBUG=true

Binary generated: ./build_debug/wmbusmeters

make DEBUG=true HOST=arm

Binary generated: ./build_arm_debug/wmbusmeters

If the meter does not use encryption of its meter data, then enter an empty key on the command line. (you must enter "")

./build/wmbusmeters --robot --meterfiles /dev/ttyUSB0 MyTapWater 12345678 ""

System configuration

Add yourself to the dialout group to get access to the newly plugged in im871A USB stick. Or even better, add this udev rule:

Create the file: /etc/udev/rules.d/99-usb-serial.rules with the content

SUBSYSTEM=="tty", ATTRS{idVendor}=="10c4", ATTRS{idProduct}=="ea60", SYMLINK+="im871a",MODE="0660", GROUP="yourowngroup"
SUBSYSTEM=="tty", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", SYMLINK+="amb8465",MODE="0660", GROUP="yourowngroup"

When you insert the wmbus USB dongle, a properly named symlink will be created: either /dev/im871a or /dev/amb8465. These symlinks are necessary if you want to pass "auto" to wmbusmeters instead of the exact serial port /dev/ttyUSBx.

Limitations

Two usb wmbus receivers are supported: IMST im871A and Amber Wireless AMB8465.

One supported meter: Multical21.

The source code is modular and it should be relatively straightforward to add more receivers and meters.

Good documents on the wireless mbus protocol:

http://www.m-bus.com/files/w4b21021.pdf

https://www.infineon.com/dgdl/TDA5340_AN_WMBus_v1.0.pdf

http://fastforward.ag/downloads/docu/FAST_EnergyCam-Protocol-wirelessMBUS.pdf

http://www.multical.hu/WiredMBus-water.pdf

http://uu.diva-portal.org/smash/get/diva2:847898/FULLTEXT02.pdf

The AES source code is copied from:

https://github.com/kokke/tiny-AES128-C

The following other github projects were of great help:

https://github.com/ffcrg/ecpiww

https://github.com/tobiasrask/wmbus-client

https://github.com/CBrunsch/scambus/

TODO: CRC checks are still missing. If the wrong AES key is supplied you probably get zero readings and sometimes warnings about wrong type of frames.