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The CMeX12S model is a reliable M-Bus master that extends the number of meters that can be used by a compatible M-Bus gateway. This device is therefore a fundamental component of a modern M-Bus technology-based measuring system infrastructure. The reliable operation of this M-Bus Master for 128 meters rests on a unique IR pass-through feature that allows data to be transmitted to the M-Bus gateway without the need to install any additional cables.

CMeX12S M-Bus Master for 128 meters

CMeX12S is an M-Bus Master which, by providing additional supply current, extends the number of meters a CMe Series Gateway is able to use. The product is equipped with a unique IR Pass Through feature which enables up to four CMe/CMeX Series devices to communicate via IR, by stacking them side-by side. CMeX12S also supports integration with existing M-Bus systems through RS232.

To ensure maximum longevity, the CMeX12S M-Bus Master for 128 meters consists of a robust polyamide casing and fail-safe, low-maintenance electronics. For ease of installation, the model can easily be mounted on a standard DIN rail.

A simple interface consisting of coloured LED lights shows whether the CMeX12S M-Bus Master for 128 meters is working correctly. The green LED lights up when the device is on, while the two yellow LEDs show that data is currently being transmitted and the red LED indicates an error message. The CMeX12S M-Bus Master for 128 meters is compatible with all M-Bus meters, ABB meters with IR interfaces and all CMe/CMeX series devices produced by Elvaco.


Casing material:
Dimensions (w x h x d):
105 x 90 x 65 mm (6 DIN modules)
Protection class:
220 g
Mounted on DIN rail (DIN 50022) 35 mm

Electrical connections

Supply voltage:
Screw terminal. Cable 0.75-2.5 mm², 0.5 Nm tightening torque
M-Bus master port:
Pin terminal solid wire 0.6-0.8 Ø mm and screw terminal 0.25-2.5 mm²
RJ45 8/8

Electrical characteristics

Nominal voltage:
100-240 VAC (±10%)
50/60 Hz
Power consumption (max):
<25 W
Power consumption (nom):
<1 W
Installation category:

Environmental specifications

Operating temperature:
-30 °C to +55 °C
Operating humidity:
5 % to 90 %, non-condensing
Operating altitude:
0-2000 m
Pollution degree:
Degree 2
Usage environment:
Indoors, can be extended with IP67 enclosure for outdoor use
Storage temperature:
-40 °C to +85 °C

Temperature sensor, margin of error

Humidity sensor, margin of error

User interface

Green LED:
Red LED:
Yellow LED 1:
M-Bus data transmission from device
Yellow LED 2:
M-Bus data transmission to device


IR, integrated M-Bus Master
M-Bus standard:
EN 13757

Wireless M-Bus

Integrated M-Bus Master

Nominal voltage, master port:
42 VDC
M-Bus baud rate, master port:
300 and 2400 bit/s
M-Bus search modes:
Primary, secondary
Maximum cable length:
5000 m (100 nF/km, maximum 90 ohm)
IR Pass Through:
Yes, with a maximum of four devices stacked side by side
Maximum number of unit loads (hardware limit):
128T/192 mA

Wireless M-Bus Receiver

M-Bus slave interface


Data storage (examples)

Mobile Network

Fixed Network (Ethernet)


All M-Bus meters, ABB meters with IR interface, CMe/CMeX Series


EN 61000-6-2, EN 61000-6-3, FCC 47 CFR
EN 62368-1 2018, UL 62368-1:2014 Ed.2], CSA C22.2#62368-1:2014 Ed.2]

Connections and Interfaces


By providing additional supply current, the CMeX12S M-Bus Master makes it possible to increase the maximum number of meters connected to a CMe series gateway to 128. It also increases the cable length between the M-Bus Master and the downstream M-Bus meters to 5 km from the amplifier, allowing greater flexibility of installation. 

With its unique pass-through feature based on IR technology, the M-Bus Master allows up to four CMe/CMeX series devices stacked side by side to communicate with each other. This allows the M-Bus Master to bring together all existing slaves, thereby enabling smart and efficient metering using the established M-Bus technology. 

Not only that, but the CMeX12S M-Bus Master for 128 meters is also compatible with existing M-Bus systems via RS232. With its robust polyamide casing and its simple but effective interface with three LED colours, the CMeX12S M-Bus Master for 128 meters combines impressive performance with ease of use.