Wiring instructions
|
| Cable color | Description |
| Power
| Brown | Power+ (10-30vdc ) |
| black | Power - | |
| Communication | yellow | 485-A |
| Blue | 485-B |
Communication protocol
Basic communication parameters
| Code | 8-bit binary |
| Data bit | 8 bit |
| Parity bit | NO |
| Stop bit | 1 bit |
| Error check | CRC |
| Baud rate | 2400bit/s, 4800bit/s, 9600 bit/s default is 4800bit/S |
4.2 Data frame format definition
Adopt Modbus-RTU communication protocol, the format is as follows:
Initial structure ?? 4 bytes of time
Address code = 1 byte
Noise Transmitter Instruction Manual (Type 485) V2.0
Function code = 1 byte
Data area = N bytes
Error check = 16-bit CRC code
End structure ?? 4 bytes of time
Address code: is the address of the transmitter, which is unique in the communication network (factory default 0x01).
Function code: The instruction function of the command sent by the host. This transmitter only uses function code 0x03 (read register data).
Data area: The data area is the specific communication data. Note that the 16bits data high byte is in front!
CRC code: Two-byte check code.
Host inquiry frame structure:
| Address code | Function code | Register start address | Register length | check code low | Check code high |
| 1 bytes | 1 bytes | 2 bytes | 2 bytes | 1 bytes | 1 bytes |
Slave transponder frame structure
| Address code | Function code | effective byte | No 1 Data area | NO2 Data area | No N Data area | Check code |
| 1 bytes | 1 bytes | 1 bytes | 2 bytes | 2 bytes | 2 bytes | 2 bytes |
Register address
| Register address
| PLC or configuration address | content | operation |
| 0000 H | 40001 | PM2.5 Upload data is the real value | Read only |
| 0000 H | 40002 | PM10 Upload data is the real value | Read only |
4.4 Communication protocol examples and explanations
Example: Read the PM value of device address 0x01
Inquiry frame:
| Address code | Function code | Start address | Data length | check code low | Check code high |
| 0x01 | 0x03 | 0x00 0x00 | 0x00 0x02 | 0xC4 | 0x0B |
Response frame: (eg read 85ug/m3 for PM2.5 and 156ug/m3 for PM10)
| Address code | Function code | effective byte | humidity | temperature | check code low | Check code high |
| 0x01 | 0x03 | 0x04 | 0x00 0x55 | 0x00 0x9c | 0xEA | 0x4A |
PM2.5 calculation:
Air quality (PM2.5/P10) transmitter instruction manual (type 485) V2.0
PM2.5:0055 H (hexadecimal) = 85=> PM2.5 = 85ug/m3
PM10 calculation:
PM10:009CH (hexadecimal) = 156 => PM10 = 156ug/m3
Package includes:
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