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The iM871A Wireless M-Bus module offers a cost-effective RF solution for smart metering applications connecting water, heat, electricity and gas meters with data concentrators in the 868 MHz frequency band. The module supports all major unidirectional and bidirectional wireless M-Bus modes (S1, S1-m, S2, T1, T2,R2, C1, C2 and combined C/T) in addition to all tolerance specifications. The iM871A is pre-qualified according to EN 300 220  and is fully compliant to the EN 13757-4 standard.

With its link budget of up to 120 dB when operating in R2 mode, the iM871A is especially addressing wireless communication requirements in challenging environments inside residential and commercial buildings. The module has an exceptionally small footprint (16.8 mm x 18.6 mm), comes equipped with a serial interface as well as analog and digital inputs and outputs to accommodate interfaces with a customer’s system. With its different ultra low power sleep modes (e.g. deep sleep < 50nA), the iM871A is well-suited for applications requiring long battery life.

Key Features

  • Supports S1, S1-m, S2, T1, T2,R2, C1, C2 and combined C/T mode
  • Small footprint 16.8 x 18.6 x 2 mm
  • Compliant to wireless M-Bus specification
    EN 13757 – 4
  • Configuration and communication via UART (SPI)
  • Optimized for low power applications
  • Max. output power up to +14 dBm
  • RF range up to 3000 m (line of sight)
  • Digital IOs / I²C-interface
  • Analog inputs
  • 128-bit AES support
  • Solderable like a SMD component
  • 50Ω pad for antenna
  • RoHS conform
  • Flexible wireless M-Bus header configuration
Frequency rangeSRD Band 863 to 870 MHz
RF output powerup to +14 dBm (50Ω pad)
Receiver sensitivityup to -109.5 dBm in R2 mode @ BER < 1 %
RF data rate4.8 / 32.768 / 100 kbps according to EN 13757
Rangeup to 3000 m (line of sight)
Operating voltage2.3 V to 3.6 V
19 mA (RX)
29mA (TX @ 9.2 dBm / 3V* / MCU idle)
Current consumption2 mA (Radio off / MCU idle @ 20 MHz)
< 1 µA (Sleep, 32kHz Quarz active)
< 50 nA (Deep Sleep)
IO’sDigital IOs
Analog Inputs
Capture und Compare
Pulse Counter
RF (EN 13757-4)
Dimension (LxWxH)16.8 x 18.6 x 2 mm
Operating temperature-20°C to +70°C