The generic CAN message type is struct can_msg (see lely/can/msg.h). This struct can represent both CAN and CAN FD frames (if CAN FD support is enabled). The can_msg struct does not correspond to any specific driver or interface. Conversion functions to and from IXXAT VCI V4 and SocketCAN can be found in lely/can/vci.h and lely/can/socket.h, respectively.

The CAN bus is a broadcast bus, so each node receives all messages. Applications typically only listen to messages with a specific CAN identifier. The CAN network interface (can_net_t, see lely/can/net.h) assists the user with processing CAN frames by allowing callback functions to be registered for individual CAN identifiers (can_recv_t). Additionally, callback functions can be registered to be invoked at specific times (can_timer_t). The CAN network interface is passive, relying on the application to feed it CAN frames or notify it of the current time. A C++ interface can be found in lely/can/net.hpp.

When processing CAN frames it is often necessary to buffer incoming or outgoing messages. A thread-safe, lock-free circular buffer (can_buf) is provided in lely/can/buf.h (see lely/can/buf.hpp for the C++ interface).