MH-Z16
Intelligent Infrared Gas Module
User’s Manual
(Version: 2.4)
Issue Date: 2019.04.29
Zhengzhou Winsen Electronics Technology CO., LTD
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 spread through electronic, copying, record ways.
Thanks for purchasing our products. In order to have 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, 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 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 case you need help during the usage in the future.
MH-Z16 Intelligent Infrared Gas Module
Profile:
MH-Z16 NDIR Infrared gas module is a common type, small size sensor, 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 digital output and PWM wave output. This common type infrared gas sensor is developed by the tight integration of mature infrared absorbing gas detection technology, precision optical circuit design, and superior circuit design.
Main features：
- High sensitivity, High resolution, Low power consumption
- Output method: UART, PWM wave &etc
- Quick response, Good stability
- Temperature compensation,
- Excellent linear output
- Long lifespan
- Anti-water vapor interference
- No poisoning
Application:
- HVAC equipment
- air quality monitoring equipment
- fresh air system
- air purification equipment
- intelligent home
- education system
- animal husbandry production
- safety protection monitoring
Main technical parameters
| Model No. | MH-Z16 |
| Detection Gas | CO2 gas |
| Working voltage | 4.5 V — 5.5V DC |
| Average current | <85mA |
| Interface level | 3.3 V |
| Measuring range | 0–5%vol range selectable (refer to tablet.) |
| Output signal | UART |
| PWM | |
| Analog output DAC (0.4–2V) | |
| Preheat time | 3 mins |
| Response Time | T90 < 30s |
| Working temperature | -10°C — 50°C |
| Working humidity | 0–95%RH (no condensation) |
| Size | 97*20*17mm (L*W*H) |
| Weight | 21 g |
| Lifespan | >5 years |
Structure
| Target Gas | Measuring Range | Accuracy | Mark |
| Carbon Dioxide (CO2) | 0–2000ppm | ± (100ppm + 6% reading value ) | Temperature compensation |
| 0–5000ppm | Temperature compensation | ||
| 0–1%VOL | Temperature compensation | ||
| 0–3%VOL | Temperature compensation | ||
| 0–5%VOL | Temperature compensation | ||
| 0–10% VOL | Temperature compensation | ||
| 0–15% VOL | Temperature compensation |
Pin Definition
| PIN No. | Description |
| PIN 4 | Vin (Voltage Input) |
| PIN 3 | GNO |
| PIN 2 | Vout (0.4–2V) |
| PIN 7 | PWM |
| PIN 1 | HD (Zero calibration, keep low electrical level for more than 7 seconds) |
| PIN 5 | UART ( RXD ) TEL electrical level data input |
| PIN 6 | UART ( TXD ) TEL electrical level data output |
Output methods
Analog output way (customized)
The Vout is proportional to the gas concentration,0.4-2V output stands for 0 to full scale.
Connection: Vin –5V, GND- Power Ground, Vout-input of ADC.
After the warm-up, Vout will show the voltage standing for the gas concentration.
If self-checking detects a fault, the output voltage is 0V.
Analog voltage output(Vo)
CO2 Concentration(ppm)= (Vo-0.4V)*full scale/(2.0V-0.4V)
| PWM output | |
| Take 0–2000ppm for example | |
| CO2 output range | 0–2000ppm |
| 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=2000x(TH-2ms)/(TH+TL-4ms) | |
| Cppm: CO2 concentration could be calculated by PWM output TH high-level output time during the cycle T1 low-level output time during the cycle | |
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 check byte is null.
| Commands | |
| 0x86 | To read CO2 concentration |
| 0x87 | To calibrate Zero Point (ZERO) |
| 0x88 | To calibrate Span Point (SPAN) |
| 0x79 | To Turn ON/OFF self-calibration function |
| 0x99 | To set detection range |
| 0x86- To read CO2 concentration | ||||||||
| To send command | ||||||||
| ByteO | Byte1 | Byte2 | Byte3 | Byte4 | ByteS | Byte6 | Byte7 | Byte8 |
| Start Byte | No. | Command | – | – | – | – | – | Checksum |
| OxFF | Ox01 | 0x86 | Ox00 | Ox00 | Ox00 | Ox00 | Ox00 | 0x79 |
| Returned value | ||||||||
| Byte° | Byte1 | Byte2 | Byte3 | Byte4 | ByteS | Byte6 | Byte7 | Byte8 |
| Start Byte | No | Concentration (High 8 bit) | Concentration (Low 8 bit) | – | – | – | – | Checksum |
| OxFF | 0x86 | HIGH | LOW | – | – | – | – | Checksum |
| CO2 concentration = HIGH * 256 + LOW For example 1. Please connect the hardware correctly. 2.To send command: FF 01 86 00 00 00 00 00 79, Returned value: FF 86 02 20 00 00 00 00 58 How to calculate concentration: convert hexadecimal 02 into decimal 2, hexadecimal 20 into decimal 32, then 2*256+32=544ppm | ||||||||
| 0x79-To turn on/off self-calibration function | ||||||||
| To send command | ||||||||
| ByteO | Byte1 | Byte2 | Byte3 | Byte4 | ByteS | Byte6 | Byte7 | Byte8 |
| Start byte | Reserved | Command | – | – | – | – | – | checksum |
| OxFF | Ox01 | 0x79 | OxAO/0x00 | Ox00 | Ox00 | Ox00 | Ox00 | checksum |
| No returned value Mark: Byte 3 is OxAO, the self-calibration function is on; Byte 3 is Ox00, the self-calibration function is off. | ||||||||
| 0x99-To set detection range | ||||||||
| To send command | ||||||||
| ByteO | Byte1 | Byte2 | Byte3 | Byte4 | ByteS | Byte6 | Byte7 | Byte8 |
| Start byte | Reserved | Command | reserved | range 24–31 bits | range 16–23 bits | range 8–15 bits | range 0–7 bits | checksum |
| OxFF | Ox01 | 0x99 | Ox00 | Datal | Data2 | Data3 | Data4 | checksum |
| No returned value. | ||||||||
Three methods to calibrate zero points (400ppm)
About zero point calibration:
This module has three methods for zero point calibration: hand-operated method, sending command method and self-calibration.
All the zero points 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 a 400ppm ambient environment. - To send command
| 0x87-To calibrate zero point | ||||||||
| Send command | ||||||||
| Byte0 | Byte1 | Byte2 | Byte3 | Byte4 | ByteS | Byte6 | Byte7 | Byte8 |
| Start Byte | reserved | Command | – | – | – | Checksum | ||
| OxFF | Ox01 | 0x87 | Ox00 | Ox00 | Ox00 | Ox00 | Ox00 | Checksum |
| No returned value Caution: zero-point means 400ppm, please ensure the module works in 400ppm CO2 gas stably for 20 min at least before send the command | ||||||||
| 0x88- To calibrate span point | ||||||||
| Send command | ||||||||
| Byte0 | Byte1 | Byte2 | Byte3 | Byte4 | ByteS | Byte6 | Byte7 | Byte8 |
| Start Byte | No. | Command | Span (High 8 bits) | Span (low 8 bits) | – | – | – | Checksum |
| OxFF | 0x01 | 0x88 | HIGH | LOW | 0x00 | Ox00 | Ox00 | Checksum |
| No returned value. If SPAN value is 2000ppm, HIGH=2000/256 LOW=2000%256 Take 2000ppm as SPAN calibration point for example: Put the module in 2000ppm CO2 gas, stability for at least 20 min. Send command FF 01 88 07 DO 00 00 00 AO for span calibrationCaution: * Please do Zero calibration before SPAN calibration. | ||||||||
3.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 power on. The zero points is 400ppm.
This method is suitable for office and home environments, not suitable for agriculture greenhouse, farm, refrigerator, etc. If the module is used in the latter environment, please turn off this function.
| Checksum calculation method | ||||||||
| Checksum = (Negative (Byte1+Byte2+Byte3+Byte4+Byte5+Byte6+Byte7)) +1 | ||||||||
| For example: | ||||||||
| ByteO | Byte1 | Byte2 | Byte3 | Byte4 | ByteS | Byte6 | Byte7 | Byte8 |
| Start Byte | No. | Command | – | – | – | – | – | Checksum |
| OxFF | Ox01 | 0x86 | Ox00 | Ox00 | Ox00 | Ox00 | Ox00 | Checksum |
| Calculating Checksum: 1.Add from Byte 1 to Byte 7: Ox01 + 0x86 + Ox00 + Ox00 + Ox00 + Ox00 + Ox00 = 0x87 2.Negative: OxFF – 0x87 = 0x78 3.Then+1: 0x78 + Ox01 = 0x79 | ||||||||
| C language | ||||||||
 | ||||||||
Cautions:
- Please avoid the pressure of its gilded plastic chamber from any direction, during welding, installation, and use.
- When placed in small space, the space should be well ventilated, especially for diffusion windows.
- The module should be away from heat, and avoid direct sunlight or other heat radiation.
- The sensor should be calibrated regularly and the calibration cycle is recommended for no more 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 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 operate properly)
- During manual zero calibration, 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.
Tel: 86-371-67169097/67169670 Fax: 86-371-60932988 Email: [email protected]
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