Basic M-Bus Device

This project provides a very basic M-Bus end-device to act as a 'slave' role in a wired M-Bus network. It builds on a fork of libmbus and provides enough functionality to:

• Respond to requests
• Respond to primary address scanning
• Respond to secondary address scanning
• Set primary address from secondary address

Note: this slave role device is only used for testing a master.

Example

You can use socat on a Linux system to emulate a point-to-point serial connection. On one side of the connection you run the mbus-device and on the other side you can play around with the various libmbus tools.

In terminal A, run socat (as a regular user), take note of the devices created, /dev/pts/NUM, here we have 12 + 13:

$ socat -d -d pty,rawer pty,rawer
2022/09/26 08:46:54 socat[528933] N PTY is /dev/pts/12
2022/09/26 08:46:54 socat[528933] N PTY is /dev/pts/13
2022/09/26 08:46:54 socat[528933] N starting data transfer loop with FDs [5,5] and [7,7]

In terminal B, start the mbus-device, here we use primary address 5:

$ mbus-device -a 5 /dev/pts/12

In terminal C, start a libmbus tool, here we request data:

$ mbus-serial-request-data /dev/pts/13 5
mbus_frame_print: Dumping M-Bus frame [type 4, 37 bytes]: 68 1F 1F 68 08 05 72 78 56 34 12 24 40 01 07 55 00 00 00 03 13 15 31 00 DA 02 3B 13 01 8B 60 04 37 18 02 1B 16 
<?xml version="1.0" encoding="ISO-8859-1"?>
<MBusData>
    <SlaveInformation>
        <Id>12345678</Id>
        <Manufacturer>PAD</Manufacturer>
        <Version>1</Version>
        <ProductName></ProductName>
        <Medium>Water</Medium>
        <AccessNumber>85</AccessNumber>
        <Status>00</Status>
        <Signature>0000</Signature>
    </SlaveInformation>
    <DataRecord id="0">
        <Function>Instantaneous value</Function>
        <StorageNumber>0</StorageNumber>
        <Unit>Volume (m m^3)</Unit>
        <Value>12565</Value>
        <Timestamp>2022-09-29T14:40:22Z</Timestamp>
    </DataRecord>
    <DataRecord id="1">
        <Function>Maximum value</Function>
        <StorageNumber>5</StorageNumber>
        <Tariff>0</Tariff>
        <Device>0</Device>
        <Unit>Volume flow (m m^3/h)</Unit>
        <Value>113</Value>
        <Timestamp>2022-09-29T14:40:22Z</Timestamp>
    </DataRecord>
    <DataRecord id="2">
        <Function>Instantaneous value</Function>
        <StorageNumber>0</StorageNumber>
        <Tariff>2</Tariff>
        <Device>1</Device>
        <Unit>Energy (10 Wh)</Unit>
        <Value>21837</Value>
        <Timestamp>2022-09-29T14:40:22Z</Timestamp>
    </DataRecord>
</MBusData>

Build & Install

First install libmbus, using the defaults it gets installed into /usr/local. Debian/Ubuntu systems support that path out of the box, but Fedora/RedHat systems may need some special incantations. The installed library provides a libmbus.pc file, which this project use to figure out the path to the library and include files.

Issuing

make

builds mbus-device in the current directory. Install it anywhere on your system, and make sure to bundle the library .so file if you move the binary to another system.

Origin & References

Made by Addiva Elektronik AB, Sweden. Available as Open Source under the MIT license. Please note, libmbus has a 3-clause BSD license which contains the advertising clause.