Instruction Manual

VTS reserves the right to implement changes without prior notice.
www.vtsgroup.com Page 2 of 16 ver. 2.0 (11.2021)
1. Introduction
This document describes functionality of air relative humidity and temperature
transducer based on integrated Sensirion SHT31-DIS-B sensor, equipped with RS-
485 interface using MODBUS RTU protocol and 0-5V / 0-10V analogue output.
NOTES:
1) Read this document carefully before attempting to start up the device!
2) The device must be installed by qualified staff only.
1.1. Functions of the device
▪ relative humidity measurement
▪ 0-5V or 0-10V analogue output (hardware selectable range) proportional to
relative humidity
▪ 3 status LEDs
▪ RS485 serial interface for remote management (setup and reading of
measurement values)
◦ MODBUS RTU protocol
◦ integrated terminating resistor 120Ω
◦ communication in HALF DUPLEX mode
◦ hardware/software configurable address in the range 1-247
◦ hardware configurable communication baud rate: 19200, 9600, 4800,
2400
◦ software configurable communication baud rate: 115200, 57600,
38400, 19200, 9600, 4800, 2400
1.2. Design Features
The main function of the RH&T transmitter is to measure air relative humidity and
temperature using an integrated Sensirion SHT31-DIS-B sensor. The measurement
result, as well as the sensor missing/error status, is processed by the built-in
microprocessor and then made available on the RS-485 bus via registers of the
MODBUS RTU protocol. Additionally, the measurement result air relative humidity is
available as analog signal on the 0-5V / 0-10V voltage output.