Winsen MH-Z19C Infrared CO2 Sensor Module User Manual

MH-Z19C Infrared CO2 Sensor Module
User Manual

Zhengzhou Winsen Electronics Technology Co., Ltd
www.winsen-sensor.com

Statement

This manual’s copyright belongs to Zhengzhou Winsen Electronics Technology Co., LTD. Without the written permission, any part of this manual shall not be copied,  translated, stored in a database or retrieval system, also can’t be spread through electronic, copying, record ways.
Thanks for purchasing our product. In order to let customers use it better and reduce the faults caused by misuse, please read the manual carefully and operate it correctly in accordance with the instructions. If users disobey the terms or remove, disassemble, or change the components inside of the sensor, we shall not be responsible for the loss.
The specific such as color, appearance, sizes &, etc., please in kind prevail.
We are devoting ourselves to product development and technical innovation, so we reserve the right to improve the products without notice. Please confirm it is the valid version before using this manual. At the same time, users’ comments on the optimized using way are welcome.
Please keep the manual properly, in order to get help if you have questions during the usage in the future.
MH-Z19C NDIR CO2 Module

Profile

MH-Z19C NDIR infrared gas module is a common type, small size sensor, pins type or terminal type, using non-dispersive infrared (NDIR) principle to detect the existence of CO2 in the air, with good selectivity, non-oxygen dependent and long life. Built-in temperature compensation; and it has UART output and PWM output. It is developed by the tight integration of mature infrared absorbing gas detection technology, precision optical circuit design, and superior circuit design.

**Applications

**

HVAC refrigeration
Air cleaner device
Indoor air quality monitoring
Smart home
Ventilation system
School

Main Features

Chamber is gold plated
High sensitivity, low power consumption
Good stability
Temperature compensation, excellent linear output
Multiple output modes: UART, PWM
Long lifespan
*Anti-water vapor interference, anti-poisoning

Main parameters

PWM
Preheat time| 1 min
Response Time| T90 < 120 s
Working temperature| -10 — 50 °C
Working humidity| 0 — 95% RH (No condensation)
Storage temperature| -2060 °C
Weight| 5 g
Lifespan| > 10 years

Detection range and accuracy

400-5000ppm
400-10000ppm

Dimensions(Pins type)

Pins connection type:

Fig3.from bottom

Dimensions(Terminal type)

Terminal connection type

Fig4.Terminal connection version

Output

PWM output

Take 400″2000ppm for example
CO2 output range| 400-2000ppm
Cycle| 1004ms±5%
Cycle start high-level output| 2ms (theoretical value)
The middle cycle| 1000ms±5%
cycle end low-level output| 2ms (theoretical value)
---|---
CO2 concentration: Cppm=2000×(TH-2ms)/(T-4ms)
CPPM: CO2 concentration could be calculated by PWM output
TH high-level output time during the cycle
T output time during the cycle(1004ms±5%)

Serial port output (UART)

Hardware connection
Connect module’s Vin-GND-RDX-TXD to users’ 5V-GND-TXD-RDX.
(Users must use TTL level. If RS232 level, it must be converted.)
Software setting
Set serial port baud rate be 9600, data bit 8 bytes, stop bit 1byte, parity bit null.

Commands

0x86| Read CO2 concentration
0x79| Turn on/off the self-calibration function
0x86- Read CO2 concentration

Sending command
ByteO| Byte1| Byte2| Byte3| Byte4| Byte5| Byte6| Byte7| Byte8
Start
Byte| Reserved| Command| –| –| –| –| –| Check
m
OxFF| Ox01| 0x86| Ox00| Ox00| Ox00| Ox00| Ox00| 0x79
Return value
ByteO| Byte1| Byte2| Byte3| Byte4| Byte5| Byte6| Byte7| Byte8
Start Byte| Command| Concentration (High 8 Byte)| Concentration
(Low 8 Byte)| –| –| –| –| Checksum
0xFF| 0x86| HIGH| LOW| –| –| –| –| Checksum
---|---|---|---|---|---|---|---|---
For example: CO2 concentration = HIGH * 256 + LOW*
How to calculate concentration: convert hexadecimal 01 into decimal 1, hexadecimal F4 into decimal 244, then 1256+244=500ppm
0x79- On/Off Self-calibration for Zero Point**

Send command-No return value
Byte0| Byte1|  Byte2|  Byte3|  Byte4|  Byte5|  Byte6|  Byte7|  Byte8
Start Byte| Reserved| Command| –| –| –| –| –| Checksum
0xFF| 0x01| 0x79| 0xA0/0x00| 0x00| 0x00| 0x00| 0x00| Checksum
No return value
NOTE: when byte3 is 0xA0, the auto-calibration function is on; when byte3 is 0x00, the auto-calibration function is turned off. The sensor factory by default is on the self-calibration function.
Checksum calculation method

Checksum = (Negative (Byte1+Byte2+Byte3+Byte4+Byte5+Byte6+Byte7))+1
For example:
Byte0| Byte1| Byte2| Byte3| Byte4| Byte5| Byte6| Byte7| Byte8
Start Byte| Reserved|  Command| –| –| –| –| –|  Checksum
0xFF| 0x01| 0x86| 0x00| 0x00| 0x00| 0x00| 0x00| Checksum
Calculating Checksum：
1、Add Byte 1 to Byte 7: 0x01 + 0x86 + 0x00 + 0x00 + 0x00 + 0x00 + 0x00 = 0x87
2、Negative: 0xFF – 0x87 = 0x78
3、Then+1：0x78 + 0x01 = 0x79
C language

char getCheckSum(char *packet)
{char i, checksum; for( i = 1; i < 8; i++) { checksum += packet[i]; }
checksum = 0xff – checksum;

Zero Point Calibration
This module has two methods for zero point calibration: the hand-operated method and self-calibration. All the zero point is at 400ppm CO2.

Hand-operated method:

Connect module’s HD pin to a low level(0V), lasting for 7 seconds at least. Before calibrating the zero point,
please ensure that the sensor is stable for more than 20 minutes in a 400ppm ambient environment.
Self-calibration:
After the module works for some time, it can judge the zero point intelligently and do the zero calibration automatically. The calibration cycle is every 24 hours since the module is powered on. The zero point is 400ppm.
This method is suitable for office and home environments, not suitable for agricultural greenhouses, farms, refrigerators, etc.. If the module is used in the latter environment, please turn off this function.
Notes

• Please avoid the pressure of its gilded plastic chamber from any direction, during welding, installation, and use.
• When placed in a small space, the space should be well ventilated, especially for the diffusion windows.
• To ensure the normal work, the power supply must be among 4.5V~5.5V DC rang, the power current must be not less than 150mA. Out of this range, it will result in the failure of the sensor. (The concentration output is low, or the sensor cannot work normally.)
• The module should be away from heat and avoid direct sunlight or other heat radiation.
• The module should be calibrated termly, the suggested period is no longer than 6 months
• Do not use the sensor in a high dusty environment for a long time
• During the zero-point calibration procedure by manual or sending command, the sensor must work in a stable gas environment (400ppm) for over 30 minutes.
• Forbid using wave soldering for the sensor.
• When soldering with a soldering iron, set the temperature to be (350 ± 5) °C, and the soldering time must be within 3 seconds.

Zhengzhou Winsen Electronics Technology Co., Ltd
Add No.299, Jinsuo Road, National Hi-Tech Zone,
Zhengzhou 450001 China
Tel: +86-371-67169097/67169670
Fax: +86-371-60932988
E-mail: sales@winsensor.com
Website: www.winsen-sensor.com

Leading gas sensing solutions supplier in China!
ISO9001 Certificated Company
Issue Date. 2021.05.14

References

• Winsen Gas Sensor_CO2 Sensor_Air Quality Sensor_Dust Sensor_CO Sensor-Winsen Electronics
• Winsen Gas Sensor_CO2 Sensor_Air Quality Sensor_Dust Sensor_CO Sensor-Winsen Electronics

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