TRUEYES Air-Q TT300 User manual

CO2 Sensor Transmitter
Air-Q User Manual
Rev. 1.0

Gas Sensor Transmitter
http://www.trueyes.co.kr October 2018 Rev. 1.0
TT300
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Model : TT300
Application
Features
This monitor measures the indoor air quality (IAQ).
Installed in the living room or bed room, Air-Q measures the level of CO₂, , temperature and humidity to maintain fresh air
quality.
The Air-Q is a highly sensitive 3 sensors and comes in a compact size at a low cost.
Analog output can be connected with other systems (ex. Ventilation or BEMS system) of Air-Q thus help notifying the air
quality regularity. It ensure that Air-Q can automatically control the air conditioner, humidifier or other ventilation devices.
CO2, Temperature and Humidity measurement
3 high sensitivity sensors
0 - 10V Analog Voltage and 0-20mA Current Output
Supply Voltage is 24Vac or 24Vdc
RS485(MODBUS) Communication
Alarm function of air status warning
User can check CO2 level, Temperature and Humidity easily through display
Compact box of size 82mmⅹ82mmⅹ25mm

Gas Sensor Transmitter
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TT300
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Parameter Min Typ Max Unit Notes
RS485 Recommended Request Time 500 1000 - ms
Analog Output Range 0 - 10 V 25mV = 25ppm
0-20mA Current Output Range 0 - 20 mA 1mA = 500ppm
Response Time
(for Analog and Current Output) - 1 - s
Alarm ‘On’ State (Relay ‘On’ State) - 2000 - ppm Alarm will be triggered
Table 2. Interface Specifications
Parameter Min Typ Max Unit Notes
Power Supply 23.5 24 24.5 V
CO2 Measuring Range 0 - 10000 ppm
Accuracy (CO2) +/-30Ppm +/-5% Above 0 ℃
+/-50ppm +/-7% Below 0 ℃
Temperature Measuring Range -10 - 50 ℃
Accuracy (Temperature) -0.4 - +0.4 ℃
Humidity Measuring Range 0 - 80 %
Accuracy (Humidity) -4 - 4 %
Table 1. General Specifications

Gas Sensor Transmitter
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TT300
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The TT300 communicates with other devices over RS485 bus. MODBUS follows RS485 communication standard.
See, Table 4, for configuration of RS485 communication.
Table 3. Communication Configuration
Baud rate 9600 bps
Stop Bits 1 bit
Parity Check None
Data Length 8 bits
The details about request and response protocols are given in, Table 5. And this protocol is followed by RTU (Remote
Terminal Unit). Description of MODBUS Protocol is given in, Table 6.
Name Bytes Description
Slave ID 1 Set Device ID, through a rotary switch.
Function Code 1 Reading and Writing Request Code.
Starting Address 2 Starting address of data bytes.
Request Quantity 2 Number of sensors to be loaded with data.
Data Length 1 Number of data bytes.
Data[n] n Number of data bytes (n), sent by sensor. (Each device sends 2 data bytes)
CRC 2 Error checking according to CRC16 standard.
Table 5. MODBUS Protocol Byte Description
No. of Bytes 1 1 2 2 2
Tx Slave ID Function Code Starting Address Request Quantity CRC
Table 4. MODBUS Protocol
No. of Bytes 1 1 1 n 2
Rx Slave ID Function Code Data Length Data[n] CRC
See Picture1, This touch switch is for configuration of RS485 Slaves’ Device ID.
If you touch the switch for 5 seconds, you hear a beeping sound. You can see the ID
increase each time you touch again after you release your finger from the switch. After
setting the desired ID, press the switch again for 5 seconds. When you hear a beep, the ID
setting is completed.
Picture 1. Touch Switch
RS 485 Interface
Touch
switch

Gas Sensor Transmitter
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TT300
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Table 7. Sensor Address Table
This is an example of serial communication protocol.
There is an example of CRC calculation for serial communication, on the page 6.
Example 1. Read Holding Registers
Slave ID 0x01
Function Code 0x03
: Read Holding Registers
Starting Address 0x0065
: for Slave Sensors
Request Quantity 0x03
: Number of Sensors
CRC16
Slave ID 0x01
Function Code 0x03
: Read Holding Registers
Data Length 0x06
: 6 bytes
Data0 0x01B3: CO2 Level
= 435 PPM
Data1 0x00CB : Temperature Level
= Data1 / 10 = 20.3 ℃
Data2 0x010A : Humidity Level
= Data2 / 10 = 26.6%
CRC16
Sub Device Starting Address
CO2 0x0065
Temperature 0x0066
Humidity 0x0067
Slave (This Transmitter) 0x0069
Function Description Function Code
Read Holding Registers 0x03
Table 6. Function Code Table
List of functions is given in, Table 7 and address of each sensor is given in Table 8.

Gas Sensor Transmitter
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TT300
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That is how the calculation of CRC (Cyclic Redundancy Check) is done. CRC16 is used in MODBUS RTU Mode.
See figure 1, This figure is flow chart of CRC16 calculation and an example in C language for it.
Figure 2. Flow Chart
Yes
Yes
No Yes
No
0xFFFF → CRC16
CRC16 XOR DATA → CRC16
NUM = 0
Move to the right CRC16
Carry over ?
CRC16 XOR POLY → CRC16
NUM = NUM + 1
NUM > 7 ?
End of message End
Start
No
#define POLYNORMIAL 0xA001
unsigned short CRC16(unsigned char *puchmsg, int dataLength){
int i;
unsigned short crc, flag;
crc = 0xFFFF;
while(usDataLen--){
crc ^= *puchmsg++;
for (i=0; i<8; i++){
flag = crc & 0x0001;
crc >>= 1;
if(flag){ crc ^= POLYNORMIAL; }
}
}
return crc;
}
void main(void){
unsigned char data[8] = {0x01, 0x01, 0x00, 0x00, 0x00, 0x03, 0, 0};
unsigned short crc16;
crc16 = CRC16(data, 6);
data[6] = (unsigned char)((crc16>>8) & 0x00FF);
data[7] = (unsigned char)(crc16 & 0x00FF);
}
Example 2. CRC16 Calculation

Gas Sensor Transmitter
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TT300
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Picture 3. Output Setting –Bottom View
Analog
Voltage Or 0-20mA Current Output Select
To set Analog Voltage or Current Output, Follow the below picture.
Connector Pin Description
Table 8. Pin Description
Value Description
Power Operation at 24VAC or 24VDC
Aout Analog Voltage or 0-20mA Current Output
RS485 RS485 Communication
Relay Output Output when over 2,000 PPM
Analog Voltage0-20mA Current

Gas Sensor Transmitter
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TT300
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Dimension
82
25
82
Dimension 1. Product Dimension

Gas Sensor Transmitter
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TT300
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Do not Use this device for outdoor use. This product is
manufactured only for indoor use.
This product must abide by the operating temperature/humidity
and the storage temperature/humidity. Do not leave or use the
device for longtime in a highly damped place in which humidity is
near 95%RH.
The standard test condition in which the product was tested is
25℃±3℃, 50±30%RH. Signal may vary slightly with environmental
condition.
Be careful when install and use as vibration/shock/falling and
cause a serious damage on the sensor.
We do not guarantee the performance of this device in case of
user installation, disassembling, assembling it at his discretion.
when installing and inspection is necessary Please, contact our
technicians.
Sensor using NDIR is influenced by air pressure. It can be used
without correction within 300m above the sea level. However, add
the output value by ±1.0% per 100m height above 300m.
Do not use it for medical, life or safety purpose.
Use when it is fixed, but not use while it is in motion.
Cautions on Usage

Gas Sensor Transmitter
http://www.trueyes.co.kr October 2018 Rev. 1.0
TT300
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During this 1 year period, our liability hereunder is
limited to the replacement of the products.
The warranty is void if the product has been damaged
by accident, unreasonable use, negligence, tampering
or other causes not arising from defects in material or
workmanship and extends to the original consumer of
the product only. Do not disable the alarm.
Warranty Information

Gas Sensor Transmitter
http://www.trueyes.co.kr October 2018 Rev. 1.0
TT300
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Revision History
Table 9. Revision History
Revision Description Date Approved
1.0 Initial Release 22 October 2018 DH Jeong

This document contains information of products and processes in development. All information provided here is subject to change without notice.
Information in this document supersedes and replaces information previously supplied in any prior versions of this document.
We do not guarantee the performance of this device in case of disassembling, operating without complying with instructions in this document.
Contact your TRUEYES representative to obtain the latest forecast, schedule and specifications. Or It may be obtained by calling [phone]~8 or
by visiting http://www.trueyes.co.kr
Copyright © 2018 TRUEYES Incorporated. All rights reserved.