Epson C I - 4 0 5 0, C I - 4 0 4 0 user manual Signal Description

Appendix A System Interface Description

2. Parallel Centronics® Interface

2.1Interface Characteristics - Connector Pin Assignment / Signal Definition

		Signal Description	Pin No.	Return line	Direction
				Pin No.
_______	*)	Control Signal from the Host. Printer reads data line	1	19	Input
STROBE		(Data 1 to Data 8) when going low.
Data 1 - 8		Data lines transfer the characters from the host to	2 - 9	20 - 27	Input
		the printer. Data 8 = most significant bit.
_____	*)	Acknowledge - Negative going pulse from the printer	10	28	Output
ACKN		indicates that the printer has received a character
		and is ready for the next data transfer.
BUSY		Control signal from the printer. A high level indicates	11	29	Output
		that the printer is unable to receive any more data.**)
PE		Paper Empty - Control signal from the printer. This	12	--	Output
		signal goes high when paper runs out, i.e. load
		upper or lower tractor, paper jam.
SELECT		Control signal from the printer. A high level indicates	13	--	Output
		that the printer is ON-LINEand ready.
LG		Logic Ground	14	--
--		not used	15	--
LG		Logic Ground	16	--
CG		Chassis Ground	17	--
VCC		+ 5 volt	18	--
SG		Signal Ground	19 - 20	--
____	*)	Control signal from the host. Does not reset the prin-	31	--	Input
INIT		ter.
______	*)	Control signal from the printer. A low level indicates	32	--	Output
FAULT		that the printer has been switched off, or the serial
		interface is active.
LG		Logic Ground	33	--
--		not used	34 - 35	--

*)

**)

Overlined signal names indicate that the signal is true when the signal level is low.

When the interface buffer is full except for the last character, BUSY will not be reset. BUSY will be reset when buffer space is available again for least 512 characters in the interface buffer. While the printer is offline (Stop Mode) BUSY remains active until the printer enters the online state again.

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