开发DBC解析器：求含两种波特率的DBC文件示例

Hey there! Totally get it—working on a DBC parser can throw up some edge cases you haven’t encountered before, especially when it comes to multi-baud rate setups. Let me share a simplified example of a DBC file that includes two different baud rates, along with a quick breakdown of how it’s structured.

Example DBC Content #

VERSION "1.0"
NS_ :
    NS_DESC_
    BA_DEF_
    BA_
    VAL_
    CAT_DEF_
    CAT_
    FILTER
    BA_DEF_DEF_
    EV_DATA_
    ENVVAR_DATA_
    SGTYPE_
    SGTYPE_VAL_
    BA_DEF_SGTYPE_
    BA_SGTYPE_
    SIG_TYPE_REF_
    VAL_TABLE_
    SIGNAL_TYPE_
    GROUP_
    SG_MUL_VAL_

# Define a custom attribute for baud rate, valid range 100k to 1M
BA_DEF_ BU_ "BaudRate" INT 100000 1000000;
# Set default baud rate to 500k
BA_DEF_DEF_ BU_ "BaudRate" 500000;

# Define bus units (ECUs)
BU_: ECU_A ECU_B ECU_C;

# Assign specific baud rates to ECUs
BA_ "BaudRate" ECU_A 250000;
BA_ "BaudRate" ECU_B 500000;
BA_ "BaudRate" ECU_C 250000;

# Messages from ECU_A (250k baud)
BO_ 1001 EngineData: 8 ECU_A
 SG_ EngineSpeed : 0|16@1+ (1,0) [0|65535] "RPM" Vector__XXX
 SG_ CoolantTemp : 16|8@1+ (1,-40) [-40|215] "degC" Vector__XXX

# Messages from ECU_B (500k baud)
BO_ 2002 TransmissionData: 8 ECU_B
 SG_ GearPosition : 0|3@1+ (1,0) [0|7] "" Vector__XXX
 SG_ TransmissionTemp : 3|8@1+ (1,-40) [-40|215] "degC" Vector__XXX

# Messages from ECU_C (250k baud)
BO_ 3003 BodyControlData: 8 ECU_C
 SG_ DoorLockStatus : 0|4@1+ (1,0) [0|15] "" Vector__XXX
 SG_ InteriorLightStatus : 4|1@1+ (1,0) [0|1] "" Vector__XXX

Key Details Explained #

• We use BA_DEF_ to create a custom BaudRate attribute for bus units (ECUs), specifying a valid range of 100,000 to 1,000,000 baud.
• BA_DEF_DEF_ sets a default baud rate of 500,000 for any ECU that doesn’t have an explicit override.
• Individual baud rate assignments are done via BA_ lines—here, ECU_A and ECU_C use 250,000 baud, while ECU_B sticks to the default 500,000.
• Messages are tied to their respective ECUs, so the parser can map each message to the correct baud rate based on its transmitting node.

This is a standard approach for multi-baud rate setups in DBC files, supported by most CAN tools and parsers.

内容的提问来源于stack exchange，提问作者strangerboy