Siemens 9014, 9016, 9015 E manual ON/X-OFF protocol

V.24/RS-232 C Interfaces

X-ON/X-OFF protocol

The following signal lines are used:

	Designation			Explanation	Direction
Pin	EIA	DIN	CCITT		from/to printer
1	AA	E1	101	PG: Protective Ground
2	BA	D1	103	TXD: Transmit Data	x
3	BB	D2	104	RXD: Receive Data	x
5	CB	M2	106	CTS: Clear to Send	x
6	CC	M1	107	DSR: Data Set Ready	x
7	AB	E2	102	SG: Signal Ground
20	CD	S1.2	108.2	DTR: Data Terminal Ready	x

After power-on, the DTR signal and the RTS signal are set to ON (positive level). When the host sets the DSR and CTS signals to ON, the printer sends an X-ON signal to the host. The printer is then ready to receive.

The data flow is controlled with the control characters DC1 (X-ON) and DC3 (X-OFF). The printer sends the control character DC1 to the host when it is ready to receive.

Ready to receive means:

–Power-on

–512 bytes free in the printer buffer

The printer sends the control character DC3 to the output system 255 bytes before “Printer buffer full”. If further data is sent to the printer after the control character, it sends a second DC3 to the printer 128 bytes before buffer overflow. The control characters are sent in the sequence DC1, DC3, DC1, DC3 etc. The only exception in the sequence is the second DC3 before buffer overflow.

Programmer Reference Guide U26169-J-Z716-1-7600