Epson 4100 manual 242, ESC Q Deselect Printer

242	IBM Proprinter Control Commands
	ESC Q (22)			Deselect Printer
	ASCII:	ESC	Q	(22)
	Control:	CTRL [	Q	(22)
	Decimal:	27	81	22
	Hexadecimal:	1B	51	16

Sets the printer so it will not accept data from the computer. This control command is intended for diagnostic purposes only. The printer remains in the off line state until Select Printer (DC1) is received, and cannot be reselected by pressing ON LINE.

DC3		Deselect Printer on Serial Port
ASCII:	DC3
Control:	CTRL S
Decimal:	19
Hexadecimal:	13	07

Deselects printer when used with a serial interface.

Treated as a null on the parallel interface. On the serial interface, the printer sends this control code to indicate its buffer is full. DC3 is the X- OFF character.

See Appendix B for details regarding software handshaking.