Industrial M-Bus to RS232 & RS485 converter, up to 10 meters - M-BUS S

T3 M-Bus S is a transparent industrial M-Bus to RS232/RS485 converter, M-Bus master for up to 10 slaves. The device operates as a master on the M-Bus side and allows the connection of up to 10 M-Bus slave devices.

T3 M-Bus S is a compact and reliable interface for integrating utility meters with supervisory systems. It acts as a transparent bridge between the electrical and protocol layers of the M-Bus and the standard serial interfaces RS-232 or RS-485. It has been designed for use in industrial and building environments where stable, repeatable communication and fast commissioning without complex configuration are required.

Thanks to its transparent protocol behavior, the device requires no programming – packets from the M-Bus network are transmitted directly to the RS-232/RS-485 interface one-to-one. This makes it easy to integrate with BMS, SCADA, or PLC systems, as well as with billing or visualization software. The transmission range of 300–19200 bps covers typical communication scenarios in metering installations and ensures stable frame reading from heat, water, electricity, and gas meters.

M-Bus (Meter-Bus) is a European standard for reading a wide range of consumption meters. Since M-Bus consists of both a protocol layer and an electrical interface, in most cases, an additional external converter is required to read a meter equipped with M-Bus. Converters with an M-Bus interface are used to collect data from meters such as gas meters, heat energy meters, electricity meters, and water meters.

Technical parameters:

• Power supply: 9~25V DC
• Operating temperature: -20°C to 80°C
• Storage temperature: -20 ~ +85°C
• Humidity: 5 ~ 95% RH (non-condensing)
• Dimensions: 17.5 mm x 56.4 mm x 98 mm (WxDxH)
• Transmission speed: 300 ~ 19200 bps
• RS-232: TxD, RxD, GND
• M-Bus Master: M1, M2
• Maximum number of M-Bus slaves: 10
• Maximum (instantaneous) power consumption at startup: 30W
• Overvoltage protection on RS-232/485 ports
• Short-circuit protection on the M-Bus line

Applications and practical benefits

• Residential and office buildings – data consolidation from water and heat meters through a single serial port, easy integration with a local billing server
• Hotels and public facilities – quick commissioning in BMS systems; monitoring and control of media consumption in specific zones
• Industrial environments – monitoring of process utilities; the optional RS-485 interface improves performance in areas with high electromagnetic interference
• Retrofit of existing installations – protocol transparency allows T3 M-Bus S to be added without modifications to existing meters

Installation, wiring and signaling

The 17.5 mm wide housing is designed for DIN TS35 rail mounting, making it easy to install in a distribution cabinet. Screw terminals (2.5 mm) ensure secure wire connection. Available terminals include M-Bus (M1/M2) lines, power supply 9–25 VDC, RS-232 port (TxD, RxD, GND), and optionally RS-485 (A+, B-, GND). LED indicators display power status and TxD/RxD communication activity, simplifying diagnostics during commissioning.

Reliability and protection

Built-in overvoltage protection on RS-232/RS-485 lines and short-circuit protection on the M-Bus side protect the device and the measurement network from incorrect wiring and voltage spikes. The operating temperature range of −20…+80 °C and protection level IP20 guarantee stability under typical industrial and building conditions. The maximum current consumption of up to 300 mA allows the use of standard 24 V DC power supplies, while low energy consumption supports efficient operation of the entire installation.

System integration

The converter is compatible with building automation and industrial IT software that communicates via serial ports. In practice, it is most commonly used for direct reading of M-Bus frames and mapping them on the supervisory system side. The RS-485 option enables extended cable lengths and bus topology operation, which is beneficial for distributed panel architectures or long cable runs.

Installation guidelines

• Use shielded twisted pair cables for segments exposed to interference; route cables away from power lines.
• Select a 24 V DC power supply with sufficient current reserve; ensure correct polarity.
• For RS-485 communication, maintain the correct A(+)/B(-) order and, if required by topology, install a terminating resistor at both ends of the bus.
• Check the LED indicators during startup: lack of Rx/Tx activity with correct power supply usually indicates a cabling issue or incorrect transmission parameters on the host side.

Why choose T3 M-Bus S?

• Compact form and quick DIN rail mounting
• Transparent operation – minimal setup time, no complex configuration
• Supports up to 10 M-Bus devices – optimal cost/performance ratio for small and medium installations
• Comprehensive protection set securing metering infrastructure
• Compatible with a wide range of meters compliant with EN 13757-2/3

Consteel Electronics provides expert advice in device selection, commissioning assistance, and post-installation support for BMS/SCADA integrators and maintenance teams. Contact us at: https://consteel-electronics.com/contact-us.