Datasheet MH-441D (Winsen) - 5

Zhengzhou Winsen Electronics Technology Co., Ltd. www.winsen-sensor.com
6.2 Digital Output
Connections: Vin-5V power, GND- Power Ground, RXD - TXD of detector, TXD - RXD of detector. Users must use TTL level, if you use RS232 level, it must be changed. Detectors can read gas concentration via UART interface of sensor, no need to calibrate.
UART Communication Protocol General setting
Baud rate 9600 Data bit 8 bit Stop bit 1 bit Check bit Null
Command:
Every command includes 9 bytes from byte0 to byte8 The start byte is 0xff The command includes sensor no and it is 0x01 by default. The command is ended with checksum. 0x86 To read gas concentration value 0x87 To calibrate sensor zero point（ZERO） 0x88 To calibrate span point(SPAN）
0x86-to read gas concentration value:
Send command Byte0 Byte1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7 Byte 8 Start bit Sensor no. Command - - - - - checksum 0XFF 0x01 0x86 0x00 0x00 0x00 0x00 0x00 0x79 Returning Byte0 Byte1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7 Byte 8 Concentration Concentration Start bit command - - - - checksum high byte low- byte 0XFF 0x86 0x02 0x60 0x47 0x00 0x00 0x00 0xD1 If the detection range is 0~100%LEL CH4, Gas concentration (unit is ppm)= [(Changing byte2 value from hexadecimal into decimalism)*256+ (Changing byte3 value from hexadecimal into decimalism)]*500 If the detection range is 0~5%vol CH4, Gas concentration (unit is ppm)= [(Changing byte2 value from hexadecimal into decimalism)*256+ (Changing byte3 value from hexadecimal into decimalism)]*100
0x87-to calibrate zero point
Send command Byte0 Byte1 Byte2 Byte3 Byte4 Byte5 Byte6 Byte7 Byte8 Start bit Sensor no. Command - - - - - checksum 0XFF 0x01 0x87 0x00 0x00 0x00 0x00 0x00 0x78 No returning Tel: 86-371-67169097 Fax: 86-371-60932988 3 Email: sales@winsensor.com