HUMIDITY TRANSDUCER RH+T-SENS-D-MODRTU VTS reserves the right to implement changes without prior notice. www.vtsgroup.com Page 1 of 16 ver. 2.0 (11.
1. Introduction This document describes functionality of air relative humidity and temperature transducer based on integrated Sensirion SHT31-DIS-B sensor, equipped with RS485 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 ▪ ▪ ▪ ▪ 1.2.
2. Technical data 2.1. General parameters of the transducer Power supply DC voltage DC 20-30 V (nom. DC 24 V) AC voltage AC 20-28 V (nom. AC 24 V) Current consumption typical TBD max TBD LED indicators See section 3.5 Signal connection Screw terminals in 5mm pitch (wire diameter ≤ 2.5mm) Housing dimensions without sampling mast with sampling mast 80x82x55mm 80x82x280mm Weight 230 g Work environment Dust-free, air, neutral gases 0ºC ÷ 50ºC Working temperature 2.2.
Response time 1) 8s 1) The prerequisite for obtaining the given response times is an air flow > 1m/s; the response time indicated is equal to one time constant corresponding to 63 % of the steady value 2.3. Parameters of temperatures measurement SHT31-DIS-B Sensor model Measurement range 0ºC ÷ 90ºC 14.5 bit (0.01ºC) Resolution Measurement accuracy (over entire measuring range) ± 0.
2.5. Parameters of serial interface Transmission Adapter RS-485 Communication protocol MODBUS RTU Transmission type HALF DUPLEX Communication baud 2400 / 4800 / 9600 / 19200 / 38400 / 57600 / 115200 Baud/s Integrated resistor terminating the RS-485 bus 120 Ω 3. Installation 3.1. ▪ ▪ ▪ 3.2.
3.3. Description of terminals OR POWER SUPPLY Notes: 1. The RXTX+ and RXTX- signals must be connected to the A and B lines of the MODBUS bus respectively. 2. The analogue output returns following voltage values: Vout VOLTAGE RANGE Re lative _ humidity 100 % VTS reserves the right to implement changes without prior notice. www.vtsgroup.com Page 6 of 16 ver. 2.0 (11.
whereas the concentration value can be calculated basing on the voltage value form using the following formula: Re lative _ humidity 100 % VOUT VOLTAGE RANGE where: VOLTAGERANGE = 5V or 10V (0-5V or 0-10V set on the configuration DIP-switch 2 – see section 3.4) Exemplary values are shown in the table below: Relative humidity [%] Voltage range = 5 V Voltage range = 10V 0 0.0V~ 0.0V~ 25 1.0V~ 2.0V~ 50 2.5V 5.0V 75 3.75V~ 7.5V~ 100 5.0V~ 10.0V~ 3.4.
1 2 3 4 5 6 Effect ON Terminating resistor 120R switched on OFF Terminating resistor 120R switched off ON Analogue output range 0-5V OFF Analogue output range 0-10V ON ON Use BAUDRATE and PAR from the software configuration ON OFF PAR - parity check (1 STOP bit) OFF ON PAR - no parity check (2 STOP bits) OFF OFF PAR - no parity check (1 STOP bit) ON ON BAUDRATE=2400 ON OFF BAUDRATE=4800 OFF ON BAUDRATE=9600 OFF OFF BAUDRATE=19200 The device address on the MODBUS bus is se
3.5. LED indicators 3.5.1. No. 1 LED POWER Description Power supply present 3.5.2. No. 1 2 LED LINK Description Data transmission on the bus No transmission 3.5.3. No. 1 2 3 4 3.6. Color / mode of light Red – flashing 1000 ms / 1000 ms Color / mode of light Green – continuous light / irregular flashing LED off LED SENSOR Description 0 – 19.9% RH 20– 79.
It is recommended that devices on the MODBUS (RS485) are connected in a daisy-chain configuration, whereby 120R terminating resistors should be connected between A and B lines of the bus at both ends of the chain (close to the outer devices). This resistor is builtin in the RH&T-SENS-D-MODBRTU transducer and can be switched on using the no. 1 switch on the configuration DIP-switch (see section 3.4).
Command table: Command no.
b01000 – RH&T transducer with SHT31-DIS-B sensor T[1..0] – value 0..3 – type 0 – duct type 1 – room type 2, 3 - reserved RH&T duct sensor in basic hardware version returns the value b1100000010000000=0xC080. 4.1.2. Bit no. SOFT_VER_REG (addr=12=0x000C) – read only 15 14 13 12 11 10 name N[3..0] 9 A[3..0] 8 7 6 5 4 B[3..0] 3 2 1 REV[3..0] Software version is represented as a sting of 4 characters: N.ABrev where N, A, B are digits in the the 0..9 range rev (with values 0..
Response format: Description Address Function code Byte counter Register values Check sum CRC Size [Bytes] 1 1 1 2*N 2 Values 1 – 247 0x03 2*N Acc. to register map 0x0000 – 0xFFFF Size [Bytes] 1 1 1 2 Values 1 – 247 0x83 1–4 0x0000 – 0xFFFF Notes See section 4.4 Error format: Description Address Function code Error code Check sum CRC 4.2.2. Notes See section 4.2.4 See section 4.
4.2.3. Writing a group of output registers (0x10) Command format: Description Address Function code Data block address Liczba rejestrów (N) Byte counter Values to be stored CRC check sum Size [Bytes] 1 1 2 2 1 2*N 2 Values 1 – 247 0x10 0x0000 – 0xFFFF 1 – 123 2*N 0x0000 – 0xFFFF 0x0000 – 0xFFFF Size [Bytes] 1 1 2 2 2 Values 1 – 247 0x10 0x0000 – 0xFFFF 1 – 123 0x0000 – 0xFFFF Size [Bytes] 1 1 1 2 Values 1 – 247 0x90 1–4 0x0000 – 0xFFFF Notes See section 4.
With even / odd parity check START 1 2 3 4 5 6 7 8 PAR STOP 5 6 7 8 STOP (STOP) Without parity check (1 or 2 stop bits): START 4.3.2. 1 2 3 4 Order of bytes in 16-bit data fields in a transmission frame The following figure shows the byte order of the 16-bit data fields.
{ nTemp = *nData++ ^ wCRCWord; wCRCWord >>= 8; wCRCWord ^= wCRCTable[nTemp]; } return wCRCWord; } VTS reserves the right to implement changes without prior notice. www.vtsgroup.com Page 16 of 16 ver. 2.0 (11.
