libmbus is an open source library for the M-bus (Meter-Bus) protocol.
The Meter-Bus is a standard for reading out meter data from electricity meters, heat meters, gas meters, etc. The M-bus standard deals with both the electrical signals on the M-Bus, and the protocol and data format used in transmissions on the M-Bus. The role of libmbus is to decode/encode M-bus data, and to handle the communication with M-Bus devices.
Wired M-Bus Specification (v4.8):
- https://m-bus.com/documentation-wired/01-introduction
- https://m-bus.com/assets/downloads/MBDOC48.PDF
Manufacturer ID list:
Example M-Bus Master:
Example M-Bus Device (slave):
./autogen.sh # only needed from git clone
./configure
make
Note: libmbus relies on the math function
pow()so when you link it with your own program ensure you have-lm. When usingpkg-configto query the system for appropriateCFLAGSandLIBS, this is handled automatically for you. However, when building on an embedded system you may not havepow(), to this end a replacement is available inlib/pow.c.
The library is fairly conservative with RAM, below is a run using an example M-Bus master that talks to an example M-Bus device over a virtual serial bus. Memory usage has been analyzed with the valgrind tool massif.
An example run where the master sends a data request to the device and prints it in verbose format (default: raw HEX dump), toggles to XML output and does the same request.
Note: below stack usage in this run peaks at 4416 bytes, which was determined to occur in the C runtime (crt0) well before the
main()function is started. In some runs the stack peaked in crt0 at 7736 bytes (!) before falling back to reasonable levels inmain().
$ ./vsb -n 2 & sleep 1
vsb: device 1 => /dev/pts/8
vsb: device 2 => /dev/pts/9
$ ../mbus-device/mbus-device -a 5 /dev/pts/9 -f ~/src/libmbus/test/test-frames/abb_delta.hex &
$ valgrind --tool=massif --stacks=yes ./mbus-master /dev/pts/8 -v
...
> req 5
...
> xml
> req 5
...
$ ms_print massif.out.842178
--------------------------------------------------------------------------------
n time(i) total(B) useful-heap(B) extra-heap(B) stacks(B)
--------------------------------------------------------------------------------
0 0 0 0 0 0
1 2,598 512 0 0 512
2 40,725 512 0 0 512
3 51,678 1,520 0 0 1,520
4 75,611 4,416 0 0 4,416
5 92,251 1,376 0 0 1,376
... before main() has started, inside crt0.o somewhere, seen up to 7,736 stack!
37 720,368 21,016 17,019 301 3,696
38 737,529 25,496 23,006 346 2,144
39 755,851 22,672 18,520 400 3,752
...
52 960,449 21,552 18,520 400 2,632
...
63 989,236 5,776 3,728 152 1,896
64 991,834 4,136 3,549 115 472
65 994,435 504 0 0 504
--------------------------------------------------------------------------------
This is a fork of the upstream https://github.com/rscada/libmbus project with a focus on porting to microcontrollers running real-time operating systems like Zephyr.
libmbus is originally from Raditex Control, see their original page at http://www.rscada.se/libmbus.