CAN FD

Once you already accept the core judgment of classic CAN, the easiest mistake when reading CAN FD is to think “the payload just grew from 8 bytes to 64 bytes, so it is faster.” That is not wrong, but it is far from enough. What really pushed CAN FD into existence was not only payload size. It was the fact that classic CAN ties arbitration and whole-frame transmission to the same bit rate, so systems increasingly wanted to keep deterministic shared-bus contention while being constrained by payload size and bus time.