Intelligent Infrared CO2 Gas Sensor (Model: MH-712B) Manual Version: 2.0 Issue Date: 10th, June 2019 Zhengzhou Winsen Electronics Technology Co., Ltd.

Statement This manual 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 database or retrieval system, also can’t spread through electronic, copying, record ways. Thanks for purchasing our product. In order to keep customers using 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...

Zhengzhou Winsen Electronics Technology Co., Ltd. MH-712B Infrared CO2 Gas Sensor 1. Product Description MH-712B is a universal type intelligent sensor to detect CO2 in air taking advantages of non-dispersive infrared (NDIR) principle. With good selectivity, no oxygen dependence, stable performance and long lifespan features, MH-712B also has built-in temperature compensation feature. It is a compact and high-performance sensor based on infrared absorption of gas detection technology, micro-machining and sophisticated circuit design. High Sensitivity and resolution, low power consumption, fast...

Zhengzhou Winsen Electronics Technology Co., Ltd. Table 2: Measurement Range and Accuracy Detected Gas Measurement Range Temperature compensation Temperature compensation Temperature compensation Temperature compensation Temperature compensation Figure 2 Sensor Sizes Stable 3: Pin Definition Pin No. Description Pin1 Vin (voltage input) Pin1 GND Pin1 Vout (0.4～2V) Pin1 UART (RXD) 0~3.3V data input Pin1 UART (TXD) 0~3.3V data output Fig3.Pins Email: [email protected]

Zhengzhou Winsen Electronics Technology Co., Ltd. Analogue Voltage Output Voltage output range 0.4 to 2V, relatively stands for 0 to full scale. Connection: Vin –5V, GND- Power Ground, Vout-ADC input. After warming-up , the Vout will show a voltage value which stands for the gas concentration. If self-checking detects a fault, output voltage is 0V. Calculation method: Cppm=(Vout-0.4V)*full scale/2.0V-0.4V Serial Output(UART) Hardware Connections Connect the Vin-GND-RXD-TXD of the sensor to the user's 5V-GND-TXD-RXD one to one correspondence. (The client must use a TTL level, and if it is an RS232...

Zhengzhou Winsen Electronics Technology Co., Ltd. 0x88-To calibrate sensor span point Byte0 Start byte The sensor has no return value Calibrate and Calculate The checksum = (invert (byte1 +byte2+byte3... + byte7)) + 1 For example Byte0 Start byte 1. Add from Byte1 to Byte7: 0x01 + 0x86+ 0 + 0 + 0 + 0 + 0 + 0 + 0 = 0x87 2. Negation: 0xff – 0x87 = 0x78 3. Add 1: 0x78 + 0x01 = 0x79 Example Program C Language Calibrate & Calculate and Routine char getCheckSum(char *packet) { char i, checksum; for( i = 1; i < 8; i++) { checksum += packet[i]; } checksum = 0xff – checksum; checksum += 1; return checksum;...