Secondary Development Serial Conversion Definition of CAN Protocol

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Serial (USB) to CAN Protocol Conversion

The serial port baud rate is default to 2 Mbps, 8 data bits, 1 stop bit, no parity check. The converter supports two communication protocols: one is a fixed 20-byte communication protocol, and the other is a variable-length communication protocol.

Variable Length Communication Format

Please select Variable length in the Protocol box, click the "Set and Start" button CAN-Variable-length.png
The internal communication of the converter uses a variable-length communication protocol, as specified below:

Variable-length communication protocol format
Field Definition Description
Packet header 0xAA Packet start flag
Type 0xC0 type
  • bit5: Frame type 0 - standard frame (frame ID 2 bytes), 1 - extended frame (frame ID 4 bytes)
  • bit4: Frame format 0 - data frame, 1 - remote frame
  • Bit0~3: Frame data length 0~8
Frame ID Extended frame 1~8 bits (byte 1)
9~16 bits (byte 2)
17~24 bits (byte 3)
25~29 bits (byte 4)
Standard framework 1~8 bits (byte 1)
9~11 bits (byte 2)
Frame data Variable length Can send or receive data 1~8 (0~8 pieces of data)
End code 0x55 Data packet end flag

Example Explanation (Standard Framework)

For example, if you send the CAN standard frame ID to 0x123, the data is 0x11 0x22 0x33 0x44 0x55 0x66 0x77 0x88, and the data format sent by the serial port is:
AA C8 23 01 11 22 33 44 55 66 77 88 55 

  * AA: Message header
  * C8: bit5 is 0 (standard frame), bit4 is 0 (data frame), bit0~3 is 8 (data length is 8)
  * 23 01: Frame ID 0x123
  * 11 22 33 44 55 66 77 88: CAN sends frame data
  * 55: End code

For example, if the CAN standard frame ID is sent to the 0x103, the data is 0x11 0x22, and the data format sent by the serial port is:
AA C2 03 01 11 22 55 

  * AA: Message header
  * C2: bit5 is 0 (standard frame), bit4 is 0 (data frame), bit0~3 is 2 (data length is 2)
  * 03 01: Frame ID 0x103
  * 11 22: CAN sends frame data
  * 55: End code

Example Description (Extended Framework)

For example, if you send the CAN extension frame ID to 0x1234567, the data is 0x11 0x22 0x33 0x44 0x55 0x66 0x77 0x88, and the data format sent by the serial port is:
AA E8 67 45 23 01 11 22 33 44 55 66 77 88 55 

  * AA: Message header
  * E8: bit5 is 1 (extended frame), bit4 is 0 (data frame), bit0~3 is 8 (data length is 8)
  * 67 45 23 01: Frame ID 0x1234567
  * 11 22 33 44 55 66 77 88: CAN sends frame data
  * 55: End code

For example, if the CAN extension frame ID is sent to the 0x1033021, the data is 0x11 0x22, and the data format sent by the serial port is:
AA E2 21 30 03 01 11 22 55 

  * AA: Message header
  * E2: bit5 is 1 (extended frame), bit4 is 0 (data frame), bit0~3 is 2 (data length is 2)
  * 21 30 03 01: Frame ID 0x1033021
  * 11 22: CAN sends frame data
  * 55: End code

Fixed 20-Byte Transceiver Protocol

Please select Fixed 20 bytes in the Protocol box, click the "Set and Start" button CAN-Fixed-20-bytes.png
The internal communication of the converter uses a fixed 20-byte communication protocol, as specified below:

Fixed 20-byte protocol format
Byte Position Field Description
0 Packet header 0xAA
1 Packet header 0x55
2 Type 0x01
3 Framework type 0x01
4 Framework format 0x01
5 Frame ID data 1 0x23
6 Frame ID data 2 0x01
7 Frame ID data 3 0x00
8 Frame ID data 4 0x00
9 Frame data length 0x08
10 Frame data 1 0x11
11 Frame data 2 0x22
12 Frame data 3 0x33
13 Frame data 4 0x44
14 Frame data 5 0x55
15 Frame data 6 0x66
16 Frame data 7 0x77
17 Frame data 8 0x88
18 Reserve 0x00
19 Check code The low 8 bits of the cumulative sum from frame type to error code (e.g., 0x93)

Example

For example, if you send a standard frame ID 0x123 with data of 11 22 33 44 55 66 77 88, the check code is calculated as follows:
0x01 + 0x01 + 0x01 + 0x23 + 0x01 + 0x00 + 0x00 + 0x08 + 0x11 + 0x22 + 0x33 + 0x44 + 0x55 + 0x66 + 0x77 + 0x88 + 0x00 = 0x293
The lower 8 bits are 0x93.

CAN Configuration Commands

CAN types of commands have two options: ox02 and ox12. One type sends and receives data in a fixed 20 bytes, while the other type sends and receives data in variable lengths. These two methods cannot communicate with each other. Please distinguish between them and choose one according to your needs
No. Definition Description
0 Message header 0xaa
1 Message header 0x55
2 Type 0x02-Setting (for sending and receiving data with a fixed 20-byte protocol); 0x12-Setting (for sending and receiving data with a variable protocol)
These two methods cannot communicate with each other. Please distinguish and choose one based on your needs
3 CAN baud rate 0x01(1Mbps), 0x02 (800kbps), 0x03 (500kbps), 0x04 (400kbps), 0x05 (250kbps), 0x06 (200kbps), 0x07 (125kbps), 0x08 (100kbps), 0x09 (50kbps), 0x0a (20kbps), 0x0b (10kbps), 0x0c (5kbps)
4 Frame type 0x01-Standard frame, 0x02 Extended frame
5 Filter ID1 1~8 bits, high byte first, low byte last
6 Filter ID2 9~16 bits, high byte first, low byte last
7 Filter ID3 17~24 bits, high byte first, low byte last
8 Filter ID4 25~32 bits, high byte first, low byte last
9 Block ID1 1~8 bits, high byte first, low byte last
10 Block ID2 9~16 bits, high byte first, low byte last
11 Block ID3 17~24 bits, high byte first, low byte last
12 Block ID4 25~32 bits, high byte first, low byte last
13 CAN mode 0x00-Normal mode, 0x01-Silent mode, 0x02-Loopback mode, 0x03-Loopback silent mode
14 Auto-retransmit 0x00—Auto-retransmit 0x01—Disable auto-retransmit
15 Backup 0x00
16 Backup 0x00
17 Backup 0x00
18 Backup 0x00
19 Checksum The low 8 bits (red part) of the cumulative sum from the frame type to the error code


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