A smart meter gateway (SMGw) is the central communication unit of an intelligent metering system (iMSys). It collects the measured values of the connected meters, encrypts them and transmits them to the authorised recipients – for example metering point operators (MSB) and grid operators. In Germany, only gateways certified by the German Federal Office for Information Security (BSI) may be used.
The three interfaces of the SMGw
A smart meter gateway strictly separates three network areas:
- LMN (local metrological network): the connection to the meters – wired via RS-485 or wireless via Wireless M-Bus. How this works in detail is explained in our article LMN explained simply.
- WAN (wide area network): remote communication with the smart meter gateway administrator (GWA) and authorised market participants – always TLS-encrypted.
- HAN (home area network) with CLS interface: local access for connection users and service technicians, as well as the CLS channel (controllable local systems) used to connect, for example, control boxes (Steuerboxen) or energy management systems.
Legal framework: MsbG and BSI TR-03109
The smart meter rollout is based on the Metering Point Operation Act (Messstellenbetriebsgesetz, MsbG) of 2016, which was significantly accelerated in 2023 by the Act on Restarting the Digitalisation of the Energy Transition (GNDEW). The technical requirements for the gateway are defined by the BSI TR-03109 family of guidelines; the manufacturer demonstrates security through certification according to Common Criteria (protection profile).
For meters, this means: they must provide a standardised, secured LMN interface in order to be connected to an SMGw – in practice, such a meter is called a base meter (Basiszähler).
SMGw in practice: connection and testing
DIINNO supplies the components around the gateway: the BAB-01 communication adapter connects existing meters to an SMGw in compliance with BSI requirements. For installation, LMN bus cables, CLS patch cables and power cables for SMGw are available. And with the LMN-Tester, you can check the meter–gateway communication, including cryptographic capabilities, with a one-click test.
Frequently asked questions
Is a smart meter gateway the same as a smart meter?
No. In everyday language, everything is often called a “smart meter”. Strictly speaking, an intelligent metering system (iMSys) consists of two components: the modern metering device (mME, the digital meter) and the smart meter gateway as the communication unit. Only together do they form the intelligent metering system.
Which interfaces does a smart meter gateway have?
Three: the LMN (local metrological network) to the meters, the WAN for remote communication with the gateway administrator and authorised market participants, and the HAN (home area network) with CLS interface for local applications such as control boxes or energy management.
Who decides whether I get a smart meter gateway?
The responsible metering point operator. The Metering Point Operation Act (MsbG) specifies which connection users must receive an intelligent metering system – in particular households with higher annual consumption as well as operators of generation plants and controllable consumption devices. All other metering points receive at least a modern metering device.
What does the BSI check in a smart meter gateway?
In Germany, smart meter gateways may only be used if they are certified by the BSI. The basis is the Technical Guideline BSI TR-03109 and a protection profile according to Common Criteria. The checks cover, among other things, encryption, key management, tamper protection and the behaviour at all three interfaces.