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18.3
Handshake Mode Communication Flow
A session starts with the receiving device sending a request using a HBR, or with the sending device sending HBS data.
The sending device does not send the next packet until it receives an ACK from the receiving device. The maximum wait
time of at least 2000 msec is reserved. Failure of a response to arrive within the wait time (at least 2000 msec) is treated
as a timeout error, and data communication is terminated.
The sending device resends the last data if the receiving device returns an ERR (error) due to checksum mismatch,
incompatible data structure, or some other reason. If an error repeats a number of times (undefined), either the sending
device or the receiving device sends an RJC to terminate the session.
A session ends after the sending device sends all the parameter sets, and sends a final EOD in response to an ACK (ACK)
from the sending device.
The same packet is resent when a checksum mismatch or incompatible data structure error is detected.
Data Receiver
Data Sender
Operation
HBR
→
Send Request (Optional)
←
HBS
Data Send
ACK
→
Acknowledge
←
HBS
Data Send
ACK
→
Acknowledge
:
:
ACK
→
Acknowledge
←
EOD
End of Data
:
Other subsessions
:
←
EOS
End of Session
Data Receiver
Data Sender
Operation
HBR
→
Send Request (Optional)
←
HBS
Data Send
ACK
→
Acknowledge
←
HBS
Data Send
ERR
→
Error
←
HBS
Data Resend
:
:
ERR
→
Error
←
EOD
End of Data
:
Other subsessions
:
←
EOS
End of Session
