CAN 是汽车控制用通信系统的国际标准,CAN XL是开发中的第3代车用CAN通信协议,它必须经过功能安全的严格检查才能满足道路零伤亡的要求。CAN XL在协议不同功能区段中用了两种不兼容的收发器。帧中FDF或XLF位的错会使接收节点认为接收的是CAN或CAN FD帧,由于收发器工作模式的差异,接收节点会出错而报错,这时两个节点各自以不同模式发帧,电平就会冲突。CAN XL协议禁止在数据域报错,这使冲突持续时间延长。关键字错形成的帧失效概率可达6*ber。如果一定要后向兼容,这种关键字单点故障引起的路径依赖错是无法解决的。

CAN is an international communication standard used In automotive control system.CAN XL is the so called third generation CAN protocol developed based on CAN.It should satisfy strict scrutiny for functional safety to satisfy requirement of zero road casualties.CAN XL uses two incompatible transceiver mode in its different functional frame segment.The key bit error in CAN XL frame at FDF or XLF will cause receiving node explaining that it is receiving a CAN or CAN FD frame.Error will happen lately due to transceiver working mode difference.Error reporting of receiving node will cause two transceiver mode in two node working simultaneously.Voltage conflict will happen.The CAN XL protocol prohibits error reporting in data field.This make error situation lasting longer.The key bit caused frame failure rate is about 6*ber.If downward compatibility is a strictly design item,route-depending error caused single fault at key bit can not be relieved.