Sharp ER-A440 Service Manual page 22

( 13 ) Receives text.
Checks the check sum, text lingth, text data, etc.
And goes to (15) if there is no error in them.
Sends NAK if any error occurs.
( 15 ) Sends ACK.
( 17 ) Terminates the operation if EOT is received.
Host
Continued from the
preceding page.
NAK
(When an error
occurs)
ACK
Satellite
( 12 ) Sends text corresponding
to the job code.
Start code Text (FDS)
Text (DATA)
( 14 ) Resends text block if NAK is received.
Resends text up to two times,and
performs error handling if NAK is still
received after the second resending
of text block.
( 16 ) Sinds the next text if ACK is received,
and sends EOT and terminates the
operation if data transfer is finalized.
EOT
Note : For the description of
each data block see section
4 (Text block formats)
– 6 –
End code
Two types of
text block
formats are
available.