Denso BHT-8000 User Manual page 168

Phase 2 with NAK
If the sending station receives a NAK from the receiving station in response to a transmission block
containing text data m, then it sends that transmission block again immediately as shown below.
If the sending station receives an ACK before receiving a NAK 10 times in succession, it continues the
subsequent message transmission.
If the sending station receives a NAK 10 times in succession or it fails to send a same transmission block,
then it shifts to phase 3 to terminate the message transmission abnormally. Even if the phase 3
terminates normally, the transmission results in an abnormal end.
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