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Theoretically, the Fault Confinement Rules could increment the Receive Error CountÕs value over all limits, when an Error Passive receiver detects additional errors without receiving any error free message. This cannot be implemented in hardware, the counterÕs value is limited by its actual number of digits. In the Reference CAN Model, the Receive Error Count has a resolution of 8 bits, which is sufficient for all purposes of fault confinement, because once the Receive Error Count has reached its Error Passive level (128), it is irrelevant how much this level is exceeded. So the Receive Error Count needs not to be incremented above the Error Passive level.
In the Reference CAN Model, the Receive Error Counter is used to count the 128 sequences needed for the Busoff Recovery Sequence. This technique is not intended as an example for hardware implementations of CAN protocol controllers, the CAN licensee is free to use other solutions best suited for the individual implementation.