Oki ML3390, User Manual

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D-28
Appendix D: Interface Data
Block format: STX + Data + ETX
Data outside a block is ignored.
Error Detection:
A block was transmitted correctly : after having received an ETX
signal an ACK signal is transmitted to the sender confirming that
the data was received without any errors.
A block was transmitted incorrectly: after having received an ETX
signal a NAK signal is transmitted to the sender indicating that an
error occured during the transmission. On receipt of the NAK sig-
nal the block has to be transmitted again.
Display of Busy Status: None
If no error was detected:
Datenempfangs-
kreis D+ -> D-
STX ETX
ACK
Datensende-
kreis B+ -> B-
Datenblock 2 Datenblock 3 Datenblock 1
STX STX ETX ETX
ACK
Data Receive
Buffer D+ -> D-
Data Send
Buffer B+ -> B-
If an error was detected:
Datenempfangs-
kreis D+ -> D-
STX ETX
NAK
Datensende-
kreis B+ -> B-
Datenblock 1 Datenblock 1 Datenblock 1
STX STX ETX ETX
NAK
Data Receive
Buffer D+ -> D-
Data Send
Buffer B+ -> B-
Data for Bitmap Graphics
The above mentioned timing diagrams are only valid as long as the
printer is in text mode. The start character STX and the stop charac-
ter ETX are only interpreted as control characters of the CBD trans-
mission protocol in text mode. Please note the following if you
want to print bitmap graphics:
Centronics Blocked
Duplex (CBD)
Protocol
Data Block 1 Data Block 2 Data Block 3
Data Block 1 Data Block 1 Data Block 1