MM20 - remote readout of M-Bus slave devices

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  • Transparent conversion of serial and Ethernet interfaces in to M-Bus interface
  • Reading of up to 20 M-Bus slave devices
  • RS-232, RS-485 and Ethernet interface
  • Ethernet parameters setup through web interface
  • Short circuit protection of M-Bus line
  • LED indications
  • Galvanic isolation of Ethernet line
  • Wide power supply range 10-28Vdc
  • 35mm DIN rail mounting




MM20 is interface converter intended for feeding and transparent reading of M-Bus slave devices. Converter has RS-232, RS-485 and Ethernet interfaces, where the lowest priority is dedicated to RS-232 and the highest to Ethernet interface. It is designed to withstand short circuit on M-Bus line. LED indicators show status and activity of M-Bus line, slave devices and Ethernet port. Power supply has wide range, from 10 up to 28Vdc. Device is suitable for 35mm DIN rail mounting.



DECODE MM20 acts on M-Bus line as standard M-bus master device which can sustain up to 20 M-Bus slave devices. It can be used for local or remote reading of calorimeters, water meters, electricity meters and other devices which fulfil M-Bus protocol. Converter is fully adjusted for industrial communications, automation processes and telemetry. For increasing system capacity, it is possible to connect more than one MM20 converter in parallel using RS-485 interface.

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Technical specification
M-Bus interface M-Bus master, up to 20 M-Bus slave devices, transparent protocol, speed 300-9600Baud; Connection: Pluggable screw clamp, RM 5mm, 2.5mm2
Serial interface RS-232 DCE, RS-485; Connection: DB9 female
Ethernet interface IEEE 802.3, 10/100 Base-T, UDP and TCP/IP; Connection: RJ45
LED indicators ON, Short, Slave, Ethernet
Overvoltage protection tranzorb on RS-485 line and M-Bus line
M-Bus port quiescent current: 0-30mA, overcurrent: 50-70mA with restart, line voltage: 30.5V  5%, internal resistance <100Ohm
M-Bus line length max 12km@300Baud, min 1km@9600Baud, cable JYSTYnx2x0.8
Power supply 10 – 28VDC
Power supply connection Pluggable screw clamp, RM 5mm, 2.5mm2
Working temperature 0 do 55°C
Dimension 95x35x87mm
Mounting 35mm DIN rail