Temperature transmitter with Modbus RTU output, for x2, without probe MAX-MB-DS-2

Professional temperature measurement solution with MODBUS RTU communication

The MAX-MB-DS-2 converter is an advanced measuring device designed for precise temperature monitoring in automation and control systems. The module works with DS1820 or DS18B20 digital sensors, providing dual-channel temperature measurement in the range of -55°C to +125°C with an accuracy of ±1°C. Thanks to MODBUS RTU communication via the RS-485 port, the device is ideal for industrial applications, HVAC systems, and building automation installations.

Design and technical parameters

A compact housing with dimensions of 18×90×65 mm (1 DIN module) allows for mounting on a standard TH-35 mm rail. The device is powered by 9÷30V DC with a maximum current consumption of 40 mA, allowing for economical power supply even in large-scale installations. The IP20 protection rating guarantees safe operation in electrical switchboards.

Electrical connections are made via 2.5 mm² screw-type terminals with a tightening torque of 0.4 Nm, ensuring secure and durable wire connections. The module operates in an ambient temperature of -20°C to +50°C, enabling installation in most typical switchboards.

Functionality and MODBUS RTU communication

The device offers 2 independent measurement channels, each supporting a separate DS1820/DS18B20 sensor connected via a 3-wire cable (red-green-white). Communication is carried out using the MODBUS RTU protocol with configurable parameters: baud rate 1200÷115200 bit/s, data bits 8, parity NONE/EVEN/ODD, and stop bits 1/1.5/2.

Each channel enables reading the current temperature as well as recording minimum and maximum values with the possibility of clearing them. Additionally, a reference correction function (±30°C) and an averaging time (1÷3600 s) are available to optimize reading stability.

Measurement accuracy and operating conditions

The sampling frequency is 10 Hz, ensuring fast updates of measurement data with a maximum query frequency of 15 Hz. The measurement error for the F&F manufactured RT-4 probe is respectively +5/-1 °C in the range from -55 to -35 °C, ±3/-1 °C from -35 to 0 °C, ±0.5 °C from 0 to 65 °C, ±1.0 °C from 65 to 85 °C, and +1/-3 °C from 85 to 125 °C.

The device signals its operating status via LEDs: green U (power) and yellow Tx (data transmission). A factory reset function is available via a configuration jumper, along with a diagnostic "read quality" parameter showing the percentage of correct readings from the last 32 samples.

The module does not support broadcast commands (address 0), and the network address can be set in the range of 1÷245. The dedicated SDS1 temperature probe is available as a separate product, allowing for flexible sensor selection for specific applications.