⚠️ Warning: you do not need to read this document to use this program. You need it only if you are developer.
⚠️ Warning: there is no description what is UART in this document. You need to have a basic electronics knowledge to understand this document.
UART port on bafang devices works on 1200 baudrate with usual setting. All messages consists of byte codes (without text meaning in ASCII or other encodings). There are four kinds of message frames in bafang protocol: Read Request, Read Response, Write Request and Write Response.
There is no special frame format for read request. Just send code from special document for your device ("Bafang UART motor protocol" or "Bafang UART display protocol"), for example 0x14 0x16, and receive response according to next section.
| Code | Length | Data | Checksum |
|---|---|---|---|
| 0xXX | 0xXX | 0xXX 0xXX ... 0xXX | 0xXX |
Code is a special byte, that determines, on which request this frame responds.
Length is a number of data bytes.
Data is a several bytes, whose meaning can be different depends on message type (message type determined by Code, every code has a description in special document for your device ("Bafang UART motor protocol" or "Bafang UART display protocol")).
Checksum can be calculated in such way: summ all other bytes (Code, Length and Data) and then take modulus of 256 from this number.
Example:
| Code | Length | Data | Checksum |
|---|---|---|---|
| 0x14 | 0x0C | 0x32 0x30 0x31 0x36 0x30 0x38 0x30 0x38 0x30 0x30 0x30 0x31 | 0x7A |
0x14 - code of motor, that retrieves serial number of motor
0x0C - 12 bytes in data section
0x32 0x30 0x31 0x36 0x30 0x38 0x30 0x38 0x30 0x30 0x30 0x31 - 201608080001 by ASCII table - serial number of motor
0x7A - (0x14 + 0x0C + 0x32 + 0x30 + 0x31 + 0x36 + 0x30 + 0x38 + 0x30 + 0x38 + 0x30 + 0x30 + 0x30 + 0x31) % 256
Write request have same structure as read response, but code consists not from one byte, but from two.
| Code | Length | Data | Checksum |
|---|---|---|---|
| 0xXX 0xXX | 0xXX | 0xXX 0xXX ... 0xXX | 0xXX |
Code is a two special bytes, that determine kind of request.
Length is a number of data bytes.
Data is a several bytes, whose meaning can be different depends on message type (message type determined by Code, every code has a description in special document for your device ("Bafang UART motor protocol" or "Bafang UART display protocol")).
Checksum can be calculated in such way: summ second byte of Code, all bytes of Length and Data, and then take modulus of 256 from this number.
Example:
| Code | Length | Data | Checksum |
|---|---|---|---|
| 0x17 0x01 | 0x0C | 0x32 0x30 0x31 0x36 0x30 0x38 0x30 0x38 0x30 0x30 0x30 0x31 | 0x67 |
0x17 0x01 - code of motor, that writes new serial number to motor
0x0C - 12 bytes in data section
0x32 0x30 0x31 0x36 0x30 0x38 0x30 0x38 0x30 0x30 0x30 0x31 - 201608080001 by ASCII table - serial number of motor
0x67 - (0x01 + 0x0C + 0x32 + 0x30 + 0x31 + 0x36 + 0x30 + 0x38 + 0x30 + 0x38 + 0x30 + 0x30 + 0x30 + 0x31) % 256
| Code | Data | Checksum |
|---|---|---|
| 0xXX | 0xXX | 0xXX |
Code is a special byte, that determines, on which request this frame responds.
Data is a byte, that has a number of parameter in data in write request package that got error during writing (usually it means that value is too low or too big). If there are more than one incorrect parameter in package, this value will show only first error. If there is no error, this value will be equal to data length.
Checksum can be calculated in such way: summ all Code, and Data and then take modulus of 256 from this number.\