On the rise: The wireless M-Bus

The transition to alternative energy sources is a fundamental issue – not just for Germany, but also for many regions across the globe.  Communication solutions are fast becoming a key component of the more efficient and stable distribution grids. They allow for realtime  monitoring that serve as a basis forthe application of coordinated control algorithms. This applies to all levels of generation and  supply, but from the perspective of communications technologies, distributed grids are certainly the most interesting: especially in light  of more ambitious demands related to cost and energy optimization of the communication nodes, ease of administration, high stability,  and wide scalability of the overall solution. The Steinbeis Transfer Center for Embedded Design and Networking at the University of  Applied Sciences in Offenburg, directed by Prof. Dr.-Ing. Axel Sikora, has developed an extensive set of solutions for this so-called  primary communication in collaboration with renowned partners. 

Not only ZigBee-based solutions, but also the Wireless M-Bus protocol is gaining in popularity. Based on the European standard EN13757, it covers the complete communication stack. In the various modes, several frequency bands and modulation types are available on the physical layer, providing a solution that best meets a variety of given requirements. The n-mode, in particular, provides a variant in the 169 MHz range, which promises long range and is suitable for difficult topologies in rural regions.

In terms of integration in applications and guaranteed cross-manufacturer interoperability, the open metering system (OMS) developed under the auspices of a number of German manufacturers plays a particularly significant role, since it supports integration into the complete user environment. This especially includes functions related to commissioning, monitoring and updates. In addition, the OMS group developed a conformity tester in the second half of last year. Employees from the Steinbeis Transfer Center for Embedded Design and Networking are actively contributing to the ongoing development of the OMS specification and the integration of security solutions.

Data protection, protection of communication elements, and the provision of secure virtual private networks (VPNs) – primarily used for protection against attacks from external networks – all play a central role in security issues. Also the German Federal Office for Information Security (BSI) has been grappling with this issue since beginning of 2011, and has developed a draft for both a protection profile for the communications unit of an intelligent metering system and a new technical guideline (BSI-TR 03109); the “Protection Profile for the Gateway of a Smart Metering System” and the “Requirements for the Interoperability of a Communications Unit in an Intelligent Metering System for Measuring Material and Energy Quantities” resulted from this work. These drafts are currently in the last annotation phase and will be passed and published in due course. Axel Sikora and his team are also actively contributing to this process. In particular, they have been named the primary contact partner to represent the M2M Alliance to both the German Federal Ministry of Economics and Technology and the BSI, and they have been responsible for the coordination of the annotation phase.

The Steinbeis Transfer Center for Embedded Design and Networking also developed firmware solutions for the various modes of the wireless M-Bus, which have now been made available for customer projects. These solutions are highly flexible on account of their integrated support of all relevant modes (C, N, S, and T). What’s more, they are highly modular in their implementation with open interfaces and numerous integration options. Users benefit from excellent portability with respect to microcontrollers and RF transceivers, with porting options for a variety of hardware products already available. The flexible portability also enables use of software in a network simulator, which allows for elegant and efficient parameter definition in large installations. The firmware solutions have proven to be highly reliable in both the testing phases of development as well as during the adoption in conformity tests.

In addition to the actual protocol implementation, tools were also developed for the running and monitoring of functions. An example of this is the product “capt2web”. It is based on the embedded Web server “emBetter”, which was designed by the Steinbeis transfer center and allows XML-based connection to the Wireless M-Bus. This enables both simple monitoring of the network as well as immediate connection to an intranet or the Internet.

• An innovative energy management and communication system was developed within the scope of the DEMAX network project: “Decentral Energy and Network Management with Flexible Energy Tariffs” – an initiative sponsored by the German Federal Ministry of Economics and Technology as part of the ProInno program for fostering innovative networks. This system enables independent energy producers and loads from both the commercial and private sectors to be included on the energy market. The Steinbeis experts developed an Internet-based communications platform based on new-generation embedded systems, which can integrate modern metering systems as well as wireless sensor/actuator networks for connection to meter counters and control of energy loads and producers.
• The ME3GAS project was set up to tackle the development of “Smart Gas Meters & Middleware for Energy Efficient Embedded Services”. It is supported by the European Commission and the German federal government within the scope of the Artemis Joint Undertaking (Artemis JU). In addition to R&D institutions, manufacturers of consumption meters and measuring devices, in addition to energy suppliers, are also contributing to the project.
• As part of the two-year WiMBex project “wireless water meter reading solution based on the EN 13757 standard, providing high autonomy, interoperability and range” – a project sponsored through the EU’s Framework Program for Research and Technological Development – project partners from Spain, Ireland, Great Britain, Hungary, and Germany are developing cost-effective radio modules for the primary communication layer, which can energize themselves through small water flow generators (maintenance-free) and network with one another automatically.

In addition to these publically sponsored projects, the Steinbeis transfer center is also involved in numerous industrial development projects. Direct license agreements with large semiconductor manufacturers, which cover the use of software solutions developed by the Steinbeis experts, are central to this work.  

Prof. Dr.-Ing. Axel Sikora
Steinbeis Transfer Center for Embedded Design and Networking (Heitersheim)
su0659@stw.de