CAN通信矩阵
1.CAN通信矩阵是什么
CAN通信矩阵（CAN Communication Matrix）通常由整车厂完成定义，车辆网络中的各个节点需要遵循该通讯矩阵才能完成信息的交互和共享。
CAN总线是一种通信形式，ISO 11898协议仅规定了数据链路层和物理层，也就是说传什么ID、传什么数据是没有定义的，这些ID段由主机厂OEM自主来进行分配，分配好之后形成一个.xls格式的表格。有了CAN通信矩阵，开发人员就知道设计的零部件应该接收什么ID的数据，需要发出什么ID的数据。
一般主机厂会给零部件供应商提供完整的CAN通讯矩阵 、DBC给需求工程师，再由需求工程师释放给，开发工程师，和测试工程师使用。但由于需求逻辑等方面的修改，DBC版本需要我们自己去更新，包括字节节点的增加，删除，修改（所在有效字节的位置，起始位置，字节长度等），所以了解CAN通信矩阵是非常有必要的。
2.如何阅读CAN通信矩阵
Property | Description | Remarks | ||||||||
Msg Name | Message name | |||||||||
Msg Type | Msg Type: Normal, NM, Diag | Normal: Normal Communication message | ||||||||
Msg ID | Message identifier | |||||||||
Msg Send Type | Send type for the message. | “ CE - Cycle and Event ” , " CA - Cycle if Active " | ||||||||
Msg Cycle Time (ms) | Cycle time of the message if it should be sent cyclically | Unit: ms | ||||||||
Msg Length (Byte) | Byte length of the message | |||||||||
Signal Name | Signal Name | |||||||||
Signal Description | Comment for the signal | |||||||||
Byte Order | Description the byte order, intel or mortoral | Intel | ||||||||
Start Byte | 起始位所在的字节序号 | |||||||||
Start Bit | 信号LSB（least significant bit）所在的位置 | |||||||||
Signal Send Type | Send type for the signal | Cycle | ||||||||
Bit Length (Bit)信号长度 | Bit length of the signal | |||||||||
Date Type | Date type of the signal | |||||||||
Resolution | Resolution value is to calculate the physical value of the signal. |
N=十六进制值转化而来的十进制值 | ||||||||
Offset | Offset value is to calculate the physical value of the signal. | |||||||||
Signal Min. Value (phys) | Physical minimum value of the signal in physical value | The "physical value" of a signal is the value of the physical quantity (e.g. speed, rpm, temperature, etc.) that represents the signal. | ||||||||
Signal Max. Value(phys) | Physical maximum value of the signal in physical value | |||||||||
Signal Min. Value (Hex) | minimum value of the signal in Hex value | |||||||||
Signal Max. Value(Hex) | maximum value of the signal in Hex value | |||||||||
Initial Value(Hex) | If no valid signal is available after network startup, the predefined value (refer to the functional requirement) shall be sent. The valid value shall be available within this time from the startup. | If this value is 0, always valid signal value will be sent in the normal operating condition. | ||||||||
Invalid Value(Hex) 无效值 | Invalid value in hex value | |||||||||
Inactive Value(Hex) | Inactive value in hex value if the message sent type is ifActive and PA | |||||||||
Unit 单位 | Unit of the signal physical value | |||||||||
Signal Value Description | Hex-physics representation of the signal value | |||||||||
Msg Cycle Time Fast(ms) | The fast cycle time of message if the Msg Send Type of message is not "Cycle" | |||||||||
Msg Nr. Of Reption | The reption number of message if the Msg Send Type of message is not "Cycle" | |||||||||
Msg Delay Time(ms) | The min time between the same ID message if the Msg Send Type of message is not "Cycle" | |||||||||