说明：  节点1向CAN节点2发送数据,数据的头两个字节分别是:节点1的ID和要求节点2回复的数据长度 节点2收到节点1的信息后,立即按照节点1的要求回复数据
(Node 1, Node 2 sends data to the CAN, the first two bytes of data are: Node 1, Node 2 ID and requirements of the data length of the back node 1 node 2, the information received immediately after the return in accordance with the requirements of the data node 1)