Epson EPI-4000 OUT, CHASSIS, Interface Specifications, Printer's chassis ground, which is

					Interface Specifications
Signal	Return
pin	pin	Signal	Direction	Description
14	-	AUTO	IN	If this signal is LOW when the printer is
		FEED		initialized, a line feed is automatically
		XT		performed by inputting a CR code (in LO
				and FX mode only). SelecType can be
				used to produce the same effect.
15	-	NC	-	Not used.
16	-	GND	-	Logic ground level.
1 7		CHASSIS		Printer's chassis ground, which is
		GND		isolated from the logic ground.
18		NC		Not used.
19-30	-	GND	-	Twisted-pair return signal ground level.
31	-	INIT	IN	When this signal goes LOW, the printer
				ignores the STROBE signal.
32	-	ERROR	OUT	This level becomes LOW when the
				printer is:
				•	in a paper-out state
				•	off line
				•	in an error state.
33	-	GND	-	Twisted-pair return signal ground level.
34		NC	-	Not used.
35	-	+5v	OUT	Pulled up to +5V through 3.3 Kohm
				resistance.
36		SLCT IN	IN	The DC1/DC3 control codes are valid
				only when this signal is HIGH (when
				SLCT IN is set to off).

Technical Specifications 7-21