The Wireless M-Bus Range Extender is a compact and cost-effective device that collects wireless M-Bus messages from utility meters and forwards them to a LoRaWAN® network.

The Range Extender allows a flexible configuration of calendar events for Wireless M-Bus reception windows as well as device filtering by Manufacturer ID and Device ID to select specific groups of meters. Even large Wireless M-Bus messages with maximum payload size can be forwarded with LoRaWAN® radio packets by means of an integrated segmentation and reassembly protocol.

This LoRaWAN certified device includes a long life Lithium battery which ensures in combination with the new ultra-low power radio module iM881A-XL a life time of up to 10 years and more.

The configuration can be managed Over-The-Air via LoRa® messages (on request) or via wired serial interface.

Wireless M-Bus Range Extender (with LoRaWAN®)

Key Features

  • WM-Bus S and combined C/T Mode supported
  • WM-Bus telegram format: A and B
  • LoRaWAN® Activation: ABP and OTA
  • EU868 LoRaWAN® Compliant (v.1.0.2)
  • Flexible configuration of calendar events and device whitelist
  • Confirmed Upload of WM-Bus messages
  • Ultra low power for long battery life


  • Automated Meter Reading
  • Home and Building Automation
  • Industrial Monitoring and Control
  • IoT (Internet of Things)
  • Smart Cities
IMST Decoder for Wireless M-Bus Range Extender This section converts the uploaded data of the Wireless M-Bus Range Extender received by a LoRaWAN® server in a human readable format.
➤ Details about the Transport Protocol can be found here or within download section for technical documents
Upload of Application Data

The upload of application data like captured Wireless M-Bus packets is implemented by means of confirmed LoRaWAN® uplink packets. Due to the adaptive payload capacity of LoRaWAN® packets a complete Wireless M-Bus packet may require more than one LoRaWAN® uplink packets. In this case a simple segmentation protocol with minimal overhead of one single byte is used. The protocol supports both, spreading of WM-Bus packets over multiple LoRaWAN® packets and transmitting of multiple WM-Bus packets in a single LoRaWAN® packet.

Application Data Upload

Transport Protocol Details

The transport protocol is used in uplink- and downlink direction on several LoRaWAN® ports which indicate the type of message content. The protocol uses a single octet header field with following format:

Transport Protocol Header

  • Last Segment Indicator (Bit 7)
    This bit indicates the last segment of a transmission if set to "1".
  • Segment Number (Bit 0 .. 6)
    The segment number starts at zero for every new transmission and will be incremented by "1" for every new segment. On receiver side it might happen that duplicated segment numbers will appear. In this case the receiver should simply ignore the duplicate segments. The segment number can wrap around from 127 to 0 in case of very large transmissions and tiny segments.

➤ Instructions & Hints
  • select corresponding port
  • add received payload by using 'add a received payload sequence' button for every single packet
  • by double clicking on a decoded data block (table), an AES decryption key can be entered

  • entered data must be in hex and in one of the following formats:
    • 123456
    • 12 34 56
    • 0x12 0x34 0x56
    • 12-34-56
    • 0x123456
  • you can add as much sequences as you want by pressing the "add a received payload sequence" button
  • not segmented payloads are interpreted after they have been added
  • segmented payloads are reassembled and interpreted, if the beginning of a sequence (Segment Number == 0) and the Last Segment Indicator according to the Transport Protocol Details are detected
  • for changing the port, you have to clear already added payload first
  • encryption modes 0 and 5 are supported

Port Selection

Entered Data

Entered Payloads
Entered AES Decryption Keys

Decoded Data

The Wireless M-Bus standard (EN 13757-4) is used in many wireless sensor and smart meter applications. These meters and sensors are communicating according to defined radio operation modes based on a standard FSK modulation with more or less range to the corresponding receiving unit.

The LoRa® modulation is a perfect mean to increase the range of wireless communication systems. The Wireless M-Bus Range Extender combines the two existing modulation technics and required communication protocol stacks in one single device.

A typical usecase for this product is the forwarding of WM-Bus messages of a configurable group of sensor / meter devices. This bridge offers a flexible way to define hourly, daily, weekly or monthly reception windows for sampling of WM-Bus messages and a large data memory for temporary buffering. Even large WM-Bus messages with maximum payload size can be forwarded with small LoRaWAN® radio packets by means of an integrated segmentation and reassembly protocol.

Besides LoRaWAN® a proprietary Point-to-Point and Point-to-Multipoint protocol (LR Base) can be selected for local configuration and message forwarding.*

* on request
Frequency rangeSRD Band 863 to 870 MHz
ModulationLoRa® Spread-Spectrum FSK Wireless M-Bus standard (EN 13757-4)
WM-Bus ModesWM-Bus S and combined C/T Mode supported
Max.Output Power+14 dBm
Data Memory8 MBit Flash
Dimensions145 x 92 x 55 mm
Operating temperature-10 °C to +55 °C
AntennaIntegrated antenna or external antenna (on request)
HousingHousing for wall mounting
Playlist: WM-Bus Range Extender - Product Presentation

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Playlist: WM-Bus Range Extender - Config Tool