But for one-to-one communication it’s okay to send longer messages. In that case, the transmitter sends a single CAN frame with as much payload as can fit, a First Frame (FF), and then a (single) receiver must be set up to reply with a Flow Control (FC) frame. This can pause, cancel, or continue the transmission, and in the case of continuing it contains two parameters that will be in use until the next FC: called STmin (Separation Time MINimum) and BS (Block Size).
The transmitter will then send one “block” of CAN frames containing payload, called Consecutive Frames (CFs), and the number of such frames sent is controlled by Block Size. The Separation Time Minimum is the amount of time that must pass between CAN frames being sent on the bus. After a block is transmitted, the transmitter waits for another FC and then repeats. When the entire payload has been transmitted, the conversation quietly stops.