Zhengzhou Winsen Electronics Technology Co., Ltd

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Infrared CO2 Sensor Module(Model: MH-Z19C)

User’s Manual(Version 1.0)
Issue Date. 2020.02.04

Zhengzhou Winsen Electronics Technology Co., Ltd
ISO9001 Certificated Company

Tel: 86-371-67169097/67169670 Fax: 86-371-60932988

Email: sales@winsensor.com

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Zhengzhou Winsen Electronics Technology Co., Ltd

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StatementThis 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 databaseor retrieval system, also can’t 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 theinstructions. If users disobey the terms or remove, disassemble, 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 products development and technical innovation, so we reserve theright to improve the products without notice. Please confirm it is the valid version before using thismanual. At the same time, users’ comments on optimized using way are welcome.
Please keep the manual properly, in order to get help if you have questions during the usage in thefuture.

Zhengzhou Winsen Electronics Technology CO., LTD.

Tel: 86-371-67169097/67169670 Fax: 86-371-60932988

Email: sales@winsensor.com

Leading gas sensing solutions supplier in China!

Zhengzhou Winsen Electronics Technology Co., Ltd

www.winsen-sensor.com

MH-Z19C NDIR CO2 Module
ProfileMH-Z19C NDIR infrared gas module is a common type, small
size sensor, using non-dispersive infrared (NDIR) principle todetect the existence of CO2 in the air, with good selectivity,
non-oxygen dependent and long life. Built-in temperaturecompensation; and it has UART output and PWM output. It isdeveloped by the tight integration of mature infrared absorbing
gas detection technology, precision optical circuit design andsuperior circuit design.

Applications*HVAC refrigeration*Smart home

*Air cleaner device*Ventilation system*Indoor air quality monitoring*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
Model No.

MH-Z19C

Detection Gas

CO2Working voltage
Average current

5.0±0.1V DC< 40mA (@5V power supply)

Peak current

125mA (@5V power supply)

Interface level

3.3 V (Compatible with 5V)Detection Range

400~5000ppm(optional)

Output signal

Serial Port (UART) (TTL level 3.3V)
PWM

Preheat time

1 min

Response TimeT90 < 120 s

Working temperature-10 ~ 50 ℃

Working humidity

0 ~ 95% RH (No condensation)

Weight5g

Lifespan> 5 years

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Detection range and accuracy
Detection Gas
Carbon Dioxide

FormulaCO2

Detection Range
400~2000ppm400~5000ppm

Accuracy± (50ppm+5% reading value)

Dimensions

Pins connection type:
PinVinGND
PWM
HdRxTxPin Definition
Positive pole of power (Vin)Negative pole of power (GND)
PWM
HD(zero point calibration, low levellasting for over 7s is effective)
UART(RXD)TTL Level data input
UART(TXD)TTL Level data output

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OutputPWM 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)/(TH+TL-4ms)
Cppm: CO2 concentration could be calculated by PWM output

TH high level output time during cycle
TL low level output time during cycle

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Serial port output (UART)
Hardware connection
Connect module’s Vin-GND-RXD-TXD to users’ 5V-GND-TXD-RXD.
(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.

Commands0x86

Read CO2 concentration

0x79

ON/OFF Self-calibration function for zero point

0x86- Read CO2 concentration
Sending command
Byte0

Byte1

Byte2

Byte3

Byte4

Byte5

Byte6

Byte7

Byte8

Start Byte

ReservedCommand-----

Checksum

0xFF

0x01

0x86

0x00

0x00

0x00

0x00

0x00

0x79

Byte0

Byte1

Byte2

Byte3

Byte4

Byte5

Byte6

Byte7

Byte8

Start Byte

CommandConcentration

Concentration----

Checksum(High 8 Byte)(Low 8 Byte)

HIGH

LOW----

Checksum

Return value

0xFF

0x86

CO2 concentration = HIGH * 256 + LOW

0x79- On/Off Self-calibration for Zero Point
Send command-No return value
Byte0Byte1

Byte2

Byte3

Byte4

Byte5

Byte6

Byte7

Byte8

Start Byte

Reserved

Command-----

Checksum

0xFF

0x01

0x79

0xA0/0x00

0x00

0x00

0x00

0x00

ChecksumNo return value
Note: when byte3 is 0xa0, the auto calibration function is turned on; when byte3 is 0x00, the auto calibration function is turned off.
The sensor factory default is to enable the automatic zero calibration function.

Checksum calculation method
Checksum = (Negative (Byte1+Byte2+Byte3+Byte4+Byte5+Byte6+Byte7))+1For example:
Byte0

Byte1

Byte2

Byte3

Byte4

Byte5

Byte6

Byte7

Byte8

Start Byte

ReservedCommand-----

Checksum

0xFF

0x01

0x86

0x00

0x00

0x00

0x00

0x00

ChecksumTel: 86-371-67169097/67169670 Fax: 86-371-60932988

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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;

About Zero Point Calibration
This module has two methods for zero point calibration: hand-operated method and self-calibration. All the zero
point is at 400ppm CO2.
Hand-operated method:
Connect module’s HD pin to 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 at 400ppm ambient environment.
Self-calibration function:
The self-calibration function means that after the sensor runs continuously for a period of time, it can
intelligently determine the zero point according to the environmental concentration and calibrate itself. The
calibration cycle is automatic calibration every 24 hours since power-on operation. The zero point of automatic
calibration is 400ppm.
The self-calibration function is suitable for office environment and home environment. However, it is not suitable
for agricultural greenhouses, breeding farms, cold storage and other places. In such places, self-calibration
function should be turned off. After the shutdown, users are required to periodically perform zero-point
detection on the sensors, and if necessary, perform zero calibration or manual zero calibration.

Notes●Please avoid the pressure of its gilded plastic chamber from any direction, during welding, installation, anduse.
●When placed in small space, the space should be well ventilated, especially for diffusion window.
●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 not longer than 6 months.
●Do not use the sensor in the high dusty environment for long time.
●To ensure the normal work, the power supply must be among 5.0V±0.1V 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 can not work normally.)●During the zero point calibration procedure by manual, the sensor must work in stable gas environment(400ppm) for over 20 minutes. Connect the HD pin to low level (0V) for over 7 seconds.
●Forbid using wave soldering for the sensor.
●When soldering with soldering iron, set the temperature to be (350 ± 5) °C, and soldering time must bewithin 3 seconds.
●As for pin version sensor, it is recommended to use soldering socket to directly insert or remove sensors forconvenient maintenance.
Tel: 86-371-67169097/67169670 Fax: 86-371-60932988
Email: sales@winsensor.com

Leading gas sensing solutions supplier in China!