5- Flow Diagram Of The Error Detection For The Parallel Port; Fig. 20. - Nibble Mode Phase Transitions - Fenix EPC1200 Operation Manual

5.8.5- Flow diagram of the error detection for the parallel port

The EPC1200 meets the IEEE-1284 standard, in the nibble mode variant.
Compatibility mode
PERIPHERAL
Data transfer
DEL EOT command not
previously sent
PERIPHERAL
does not have
data to send
Host system does
not receive data
Host system
byte.
busy
Peripheral does
Data not
not have more
available
data to send
NOTES:
(1) The circles represent the IEEE1284 phases.
(2) This diagram can not be considered as a true state diagram.
(3) The host system can request the negotiation phase at any time, but the printer will
only return a status byte if the host system has send the DEL EOT command
previously.
(4) If the printer control of the host system does not have enabled or implemented the nibble
mode according to the IEEE-1284 interface, only the compatibility mode will make
communication possible. In this case, the error signaling is reduced to the information
provided by the PError and nFault pins.
Host system
Data transfer
PERIPHERAL
Busy,ACK,PE,/ERR
HOST SYSTEM requires
reverse transfer
Negotiation
Reverse data
transfer

Fig. 20. - Nibble mode phase transitions

EPC1200 SERIES OPERATION MANUAL
HOST
SYSTEM.
Forward idle
Host system
requires
data byte
Interface
END
returns to
compatibility
mode
Negotiation
HOST SYSTEM
error
END request
DEL EOT command
send previously
PERIPHERAL has
data to send
Host system
busy.
Data
available
25/56