VTS Group - Air Handling and Conditioning units, Air Curtains, Heating UnitsVTS Group - Air Handling and Conditioning units, Air Curtains, Heating Units
Instruction Manual for VTS models including: RH T-SENS-D-MODRTU Compact Floor-Mounted Air Handling Units, RH T-SENS-D-MODRTU, Compact Floor-Mounted Air Handling Units, Floor-Mounted Air Handling Units, Air Handling Units, Handling Units, Units
Compact Floor-Mounted Air Handling Units | Ventus - VTS Group
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DocumentDocumentHUMIDITY TRANSDUCER RH+T-SENS-D-MODRTU
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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
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 120 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.
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2. Technical data 2.1. General parameters of the transducer
Power supply
DC voltage AC voltage
Current consumption
typical max
LED indicators
Signal connection
Housing dimensions without sampling mast with sampling mast
Weight Work environment Working temperature
2.2. Parameters of humidity measurement
Sensor model Measurement range Resolution Measurement accuracy (@ T=25ºC)
- in the range 0 ÷ 90% RH - in the remaining measurement range Hysteresis Sampling frequency
DC 20-30 V (nom. DC 24 V) AC 20-28 V (nom. AC 24 V)
TBD TBD See section 3.5 Screw terminals in 5mm pitch (wire diameter 2.5mm)
80x82x55mm 80x82x280mm
230 g Dust-free, air, neutral gases
0ºC ÷ 50ºC
SHT31-DIS-B 0÷ 100% RH
14.5 bit (0.01% RH)
± 2% RH ± 3% RH ± 0.8% RH
1 Hz
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Response time 1)
8 s
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
Sensor model
SHT31-DIS-B
Measurement range Resolution Measurement accuracy (over entire measuring range) Sampling frequency
0ºC ÷ 90ºC 14.5 bit (0.01ºC)
± 0.25ºC 1 Hz
Response time 1)
2 s
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
2.4. Parameters of analogue output
Output type Output range Resolution
in [mV] for the range 0-10 V in [mV] for the range 0-5 V Loading capacity Refreshing period
voltage 0-5 V or 0-10 V
11.5 bit 3.2mV~ 1.6mV~ RL > 1 k
1 s
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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
3. Installation 3.1. Safety The device must be installed by qualified staff only! All connections must be made in accordance with wiring diagrams
shown in this document!
Check all electrical connections prior to commissioning! 3.2. Device design
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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 100 %
Re lative
_
humidity
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whereas the concentration value can be calculated basing on the voltage value form using the following formula:
Re lative
_
humidity
100 % VOLTAGE RANGE
VO U T
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
0
0.0V~
25
1.0V~
50
2.5V
75
3.75V~
100
5.0V~
Voltage range = 10V
0.0V~ 2.0V~ 5.0V 7.5V~ 10.0V~
3.4. Configuration of MODBUS bus, serial port and analogue output
0 OFF
1 ON
CONFIGURATION
ADDRESS
The purpose of the consecutive switches of the left DIP-switch is as follows (default values are in bold)
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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 set using the right DIP-switch:
123 4 5 6 7 8
Effect
ON
Address = address + 1
ON
Address = address + 2
ON
Address = address + 4
ON
Address = address + 8
ON
Address = address + 16
ON
Address = address + 32
ON
Address = address + 64
ON
Address = address + 128
Note: the configuration set by the means of DIP-switches is read once after device restart (after switching on the power or pressing the RESET button). For this reason, if the DIPswitch settings are changed during operation, then after changing the settings, it is
necessary to restart the device by pressing the RESET button or temporarily unplugging the
power supply.
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3.5. LED indicators
3.5.1. LED POWER
No.
Description
1
Power supply present
Color / mode of light Red flashing 1000 ms / 1000 ms
3.5.2. LED LINK
No.
Description
1
Data transmission on the bus
2
No transmission
Color / mode of light Green continuous light / irregular flashing
LED off
3.5.3. LED SENSOR
No.
Description
1
0 19.9% RH
2
20 79.0% RH
3
80 100% RH
4
Sensor missing or other error
3.6. Recommendations for installation
Color / mode of light
Yellow continuous light Green continuous light Red continuous light Red flashing 100 ms / 600 ms
TRANSDUCER (1)
TRANSDUCER (2)
TRANSDUCER (n)
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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).
Moreover, shielded cables should be used when the device is operated in high interference environments and the shield should be connected to the nearest PE point on the power supply side.
4. MODBUS protocol
4.1. Register map
Register R/W no.
0x0000 R 0x0001 R 0x0002 R
Name
RH_REG TEMP_REG TEST_VAL_REG
0x0003 RW 0x0004 RW
0x0005 RW
0x0006 R 0x0007 R 0x0008 R 0x0009 R 0x000A R
0x000B R 0x000C R
PASS_REG COMMAND_REG
PARAM_REG
----STATUS_REG
DEV_ID_REG SOFT_VER_REG
Values
Notes
0 ÷ 1000 -4000 ÷ 12380 1000 (0x3E8)
Relative humidity (1=0.1%; 1000=100%)
Temperature [ºC] (1=0.01ºC) with sing Test value to verify the correctness of
register readings
1234 (0x04D2)
password register
1 / 2 / 3 / 4 / 5 /
command register
6
Refer to
parameter register
command table
0
reserved
0
reserved
0
reserved
0
reserved
0 / 1 / 2 Status register (0: NO SENSOR; 1: SENSOR OK,
2: ERROR)
0xC100
Device identification
0 0x9999
Software version
(e.g. 0x3210 means software 3.21a)
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Command table:
Command no. 1 2
Function Set device address Set the baud rate
3
4 6 Notes:
Set parity bits Set stop bits Device reset
Parameters
1-247 (1 default value)
24 2400 bit/s 48 4800 bit/s 96 9600 bit/s 192 19200 bit/s = default value 384 38400 bit/s 576 57600 bit/s 1152 115200 bit/s
0 NO PARITY, no parity bit (default value) 1 EVEN PARITY, even parity bit 2 ODD PARITY, odd parity bit
1 1x STOP, 1 stop bit (default value) 2 2x STOP, 2 stop bits
1 software reset of the device 2 software reset of sensor module
Reading registers from addresses not listed in this table results in 0x02 exception.
Specifying an incorrect or out-of-range parameter value results in entering the value 0xEEEE into the command register.
The device is configured by writing three registers (password / command / parameter) at the same time using the 0x10 function with the corresponding values according to the command table, or by writing single registers (using 0x06 or 0x10 function) with the latter writing of a (valid) password causing the execution of the command.
During a single password entry (both with function 0x06 and 0x10) in case of a password match, the correctness of information in command and parameter registers is checked and if correct, the command is executed.
4.1.1. DEV_ID_REG (addr=11=0x000B) read only
Bit no. 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
name
DEV[4..0]
HV[1..0]
OPTIONS[4..0]
0 0 T[1..0]
This register is used to store device ID. Meaning of bits:
DEV[4..0] = b11000 fixed value meaning "air parameter sensors" HV[1..0] value 0..3 hardware version OPTIONS[4..0] values 0..31 device type
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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. SOFT_VER_REG (addr=12=0x000C) read only
Bit no. 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
name
N[3..0]
A[3..0]
B[3..0]
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..9) is a letter in the range `a'...'j'. Examples: 0x0000 represents software version: 0.00a; 0x4321 4.32b ; 0x2345 2.34f
4.2. Protocol functions
CODE 0x03 (dec 3) 0x06 (dec 6) 0x10 (dec 16)
Name Reading N x 16-bit registers Writing single 16-bit registers Writing N x 16-bit registers
4.2.1. Reading the contents of a group of output registers (0x03)
Command format:
Description Address
Function code Data block address Number of registers (N)
Check sum CRC
Size [Bytes] 1 1 2 2 2
Values
1 247 0x03
0x0000 0xFFFF 1 125
0x0000 0xFFFF
Notes See section 4.4
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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
Error format:
Description Address
Function code Error code
Check sum CRC
Size [Bytes] 1 1 1 2
Values 1 247 0x83 1 4 0x0000 0xFFFF
4.2.2. Writing single 16-bit registers (0x06)
Command format:
Description Address
Function code Register address Value to be stored Check sum CRC
Size [Bytes] 1 1 2 2 2
Values
1 247 0x06
0x0000 0xFFFF 0x0000 0xFFFF 0x0000 0xFFFF
Response format:
Description Address
Function code Register address Value to be stored Check sum CRC
Error format:
Description Address
Function code Error code
CRC check sum
Size [Bytes] 1 1 2 2 2
Size [Bytes] 1 1 1 2
Values 1 247 0x06 0x0000 0xFFFF 0x0000 0xFFFF 0x0000 0xFFFF
Values 1 247 0x86 1 4 0x0000 0xFFFF
Notes
See section 4.4 Notes
See section 4.2.4 See section 4.4
Notes
See section 4.4
Notes
See section 4.4 Notes
See section 4.2.4 See section 4.4
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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
Notes See section 4.4
Response format:
Description Address
Function code Data block address Number of registers (N)
CRC check sum
Size [Bytes] 1 1 2 2 2
Values
1 247 0x10
0x0000 0xFFFF 1 123
0x0000 0xFFFF
Notes See section 4.4
Error format:
Description Address
Function code Error code
CRC check sum
Size [Bytes] 1 1 1 2
Values 1 247 0x90 1 4 0x0000 0xFFFF
Notes
See section 4.2.4 See section 4.4
4.2.4.
CODE 0x01 0x02 0x03 0x04
Description of errors
Name Invalid function Invalid data range / address Invalid data value SLAVE device error
4.3. Data format
4.3.1. Character / byte format
The following figure shows the format of a byte transmitted in the MODBUS RTU protocol. Each transmitted character has 10 or 11 bits, which are sent in order from the least significant to the most significant.
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With even / odd parity check START 1 2 3 4 5 6 7 8 PAR STOP
Without parity check (1 or 2 stop bits): START 1 2 3 4 5 6 7 8 STOP (STOP)
4.3.2. 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. For 16-bit data fields, the correct byte order is that the older byte is transmitted first, then the younger byte (HILO - BIG ENDIAN), while for the CRC field the younger byte is transmitted first, then the older byte (LO HI - LITTLE ENDIAN).
REG-0 (16bit)
HI
LO
DATA
REG-1 (16 bit)
REG-N (16bit)
...
HI
LO
HI
LO
CHECK SUM
CRC (16bit)
LO
HI
4.4. CRC check sum
WORD CRC16 (const BYTE *nData, WORD wLength)
{ static const WORD wCRCTable[] = { 0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241, 0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440, 0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40, 0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841, 0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40, 0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41, 0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641, 0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040, 0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240, 0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441, 0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41, 0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840, 0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41, 0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40, 0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640, 0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041, 0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240, 0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441, 0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41, 0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840, 0x7800, 0xB8C1, 0xB981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41, 0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40, 0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640, 0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041, 0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241, 0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440, 0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40, 0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841, 0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40, 0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41, 0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641, 0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040};
BYTE nTemp; WORD wCRCWord = 0xFFFF;
while (wLength--)
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{ nTemp = *nData++ ^ wCRCWord; wCRCWord >>= 8; wCRCWord ^= wCRCTable[nTemp];
} return wCRCWord; }
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