City of Aachen
Large-scale energy data monitoring
The city of Aachen took the necessary replacement of an older generation of data loggers as an opportunity to connect its M-Bus-capable consumption meters to MQTT communication. The gateways from MBS GmbH ensure greater operational reliability and flexibility.
Germany's westernmost city has been very active in energy policy and climate protection for 30 years. It was awarded the European Energy Award in Gold back in 2011 and has been participating in the EU's "100 climate-neutral cities" mission since 2022. The operator of numerous properties also launched an integrated climate protection concept three years ago in order to accelerate the reduction of greenhouse gases.
"The energy assessment of municipal properties plays a key role in this," says Markus Gilliam, Team Leader Energy Management and Building Automation at the City of Aachen. His 16-strong team not only manages the building automation systems using central control technology, but has also recently been entrusted with the planning and implementation of municipal photovoltaic systems. It also collects all consumption data for the energy management system (EMS) for municipal properties such as schools, daycare centers, swimming pools and gyms.
In focus: energy assessment of properties
The hardware and software used had become outdated and in some cases could only be operated with great effort. The new devices - data loggers or gateways - needed to be durable and compatible with the existing M-bus system and offer the option of remote maintenance. The data was to be sent to the EMS via CSV file format on a transitional basis.
The first phase of the project began with testing various products from different manufacturers. "The result was extremely unsatisfactory," recalls Jannik Zimmer, responsible for the operation and development of the EMS in Aachen. One device was not suitable for continuous operation, another had no interface to the EMS, others failed to exchange data via CSV (MQTT in the future) or remote maintenance. As a result, the project participants drew up a focus list that included a direct interface for MQTT (Message Queue Telemetry Transport), the most important network protocol for machine-to-machine communication (M2M), in addition to the industrial suitability of the products sought. A web interface for remote maintenance and a power supply with both direct and alternating current completed the list.
In demand: industrial suitability, M-Bus support ...
The criteria of industrial suitability, longevity and M-Bus support ultimately led those responsible to Krefeld-based MBS GmbH. Their versatile universal gateways are based on a single product platform. Numerous functions - such as a web interface for diagnostics, meter scan and readout, live values, restart plus free design of a CSV file - support users in their work. With numerous communication protocols, the devices offer the right solution for almost every requirement.
The Aachen-based company opted for 204 Double-X Universal Gateways M-Bus with RS-485 and 25 to 200 data points as well as the driver configuration M-Bus plus MQTT. In addition, 12 Single-X Universal Gateways Modbus RTU with RS-485 and BACnet and 400 to 2,500 data points were to be used. Gilliam: "The large selection of different bus protocols and the associated flexibility in use quickly won us over."
... and flexibility
With this new equipment, the team now focused on data transmission via MQTT. However, it turned out that the EMS could not communicate smoothly with the gateway drivers, as each manufacturer can design an MQTT driver individually within the scope of the specification. It was useful that MBS GmbH was able to contribute not only the right products, but also its solution expertise to the project: "We clarified the properties of the respective interfaces and took over the coordination between the three parties," explains Nils-Gunnar Fritz, Managing Director of MBS GmbH. "Ultimately, we decided to expand our MQTT interface in order to test this solution again afterwards." The success proved the participants right. Various adjustments were made to stabilize the communication so that the data was finally transmitted from the field to the EMS in a compliant manner.
Products plus solution expertise
Since December 2021, most of the M-Bus gateways have been in regular operation without failure. "This means we have achieved our goal, because the communication works perfectly," Zimmer sums up. The stability of internet access is still a problem at some readout stations. However, the fact that the gateway stores the data retrospectively for three days is sufficient to bridge such disruptions.
The benefits of the solution are obvious for the Aachen-based energy management specialists. Their new hardware is more reliable, produces fewer failures and definitely offers more operational reliability. The simplified data transmission also has fewer sources of error. Flexibility is also important to Gilliam: "If we want to use other communication protocols, the gateways can also be used for these applications." Zimmer adds: "Because the data read out every 15 minutes is no longer processed four times a day, but every five minutes, we can react much faster if necessary." The Aachen-based company is also unanimously satisfied with the service quality and support provided by MBS GmbH, which responded quickly and competently to all questions.
Perfect communication in every respect
Inspired by this positive experience, there are already further plans for the use of Universal Gateways. For example, for communication between Modbus RTU and BACnet/IP or for monitoring the newly built photovoltaic systems via Modbus TCP and MQTT. Finally, Gilliam would like to use the gateways as BACnet data loggers for commissioning management. This way, it is possible to check whether the systems are working properly before acceptance on site.
