CAN bus is connected to the physical bus through two output terminals CANH and CANL on the interface chip of CAN controller. The state of CANH terminal can only be high level or floating state, and the state of CANL terminal can only be low level or floating state.

At present, SJA 1000 is widely used as the interface chip of CAN bus to convert data into CAN data frames, but PCA82C250 must be used to connect CAN bus. More precisely, SJA 1000 and PCA82C250 must be used in pairs.

Extended data:

CAN bus is connected to the physical bus through two output terminals CANH and CANL of CAN transceiver interface chip 82C250, but the state of CANH terminal can only be high or floating, and the state of CANL terminal can only be low or floating.

This ensures that it will not appear in the RS-485 network, that is, when the system goes wrong and multiple nodes send data to the bus at the same time, the bus will be short-circuited and some nodes will be damaged.

Moreover, the CAN node has the function of automatically turning off the output when a serious error occurs, so that the operation of other nodes on the bus is not affected, thus ensuring that the bus will not be in a "deadlock" state because of the problems of individual nodes, as in the network.

Reference source; Baidu encyclopedia -CAN bus