Epson TK14 operation manual Flow diagram of the error detection for the parallel port, End

FENIX IMVICO TK14 OPERATION MANUAL

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

The TK14 meets the IEEE-1284 standard, in the nibble mode variant.

Compatibility mode

PERIPHERAL	Host system	HOST
	Data transfer
		SYSTEM.
Data transfer
		Forward idle
	PERIPHERAL
	Busy,ACK,PE,/ERR

Interface	END
returns to
compatibility
mode
Negotiation
	HOST SYSTEM
error	END request

DEL EOT command not		HOST SYSTEM requires
		reverse transfer
previously sent
				DEL EOT command
				send previously
PERIPHERAL
does not have		Negotiation		PERIPHERAL has
data to send				data to send
	Host system does
Host system	not receive data	Reverse data	Host system	Host system
	byte.	transfer
				busy.
busy	Peripheral does		requires
Data not			data byte	Data
	not have more
available				available
	data to send

Fig.3.11- Nibble mode phase transitions.

NOTES:

(1)The circles represent the IEEE1284 phases.

(2)This diagram can not be considered as the true state diagram.

(3)The host system can request the negotiation phase at any time, but the TK14 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.

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