Denso BHT-4000 User Manual page 97

Abnormal termination of phase 1 (Abort of phase 1)
If the sending station receives no ACK from the receiving station after sending an
ENQ 10 times in succession, it sends an EOT to the receiving station after three
seconds from the 10th ENQ to terminate the message transmission abnormally.
Sending
station
Chapter 3. Communications Operations of BHT-4000
ENQ(1)
3 sec.
ENQ(2)
3 sec.
ENQ(3)
ENQ(10)
3 sec.
EOT
Abnormal
termination
87
Receiving
station