HP WP36/50 5. RS-232CCable Connection, 4.1 PRESCRIBE FRPO D0 command, 5.1 Obtain a Suitable RS-232CCable, 5.2 Connecting the Printer to the Computer, Error, Error

Appendix B Host Computer Interface

H5: Protocol logic

Parameter value	Meaning
0	Combination of 1 and 3 below
1	DTR/DSR, positive logic
2	DTR, negative logic
3	XON/XOFF
4	ETX/ACK
5	XON/XOFF recognized only as protocol

Table B-6

The factory default setting is 0.

H6: Buffer nearly-full threshold

This is a percentage from 0 to 99. The factory default setting is 90.

H7: Buffer nearly-empty threshold

This is a percentage from 0 to 99. The factory setting is 70. The factory default settings of the buffer nearly-full and nearly -empty thresholds (H6 and H7) are subject to change without notification.

The gap between the nearly-full and nearly-empty thresholds allows the computer to send a fairly large amount of data in a continuous stream.

H8: Received-data buffer size

This is the size of the input buffer, specified in units of 10 Kbytes. The factory-set value is 6, meaning 60 Kbytes.

4.1 PRESCRIBE FRPO D0 command

The PRESCRIBE FRPO D0 command provides control over XON/XOFF operation when an error occurs on the serial in- terface. The following table summarizes the error status corresponding to different D0 values.

Timing of XON transfer to host	Serial interface error
	Error	Error
while Ready or Waiting
	not resolved	resolved
XON sent every 3 to 5 seconds	D0=0	D0=1
	(default)
XON not sent	D0=10	D0=11
Table B-7

5. RS-232C Cable Connection

5.1 Obtain a Suitable RS-232C Cable

Make sure that the RS-232C cable is wired correctly. The cable must be a null modem cable; that is, one in which pin 2 on either end of the cable is connected to pin 3 on the other end. You cannot use a straight cable such as IBM communication adapter cable type 1502067 unless you purchase a null modem adapter.

1	cable.Remove the plastic cover from the printer end of the
2
	Next to each of the wires inside the cable is a bare
	shield wire. Solder all these shield wires together
	into a single bundle.
3	Using a section of flat wire about 3 mm wide and 15
	mm long, connect the bundle of shield wires to the
	metal facing of the connector. Check that the solder
	connections are secure.
4	Desolder wires 2 and 3, then resolder them in
	crossed configuration. Solder wire 2 to pin 3 and
	wire 3 to pin 2. Cover the solder joints with ther-
mofit tube.
5	Cut wires 4, 5, 6, and 20.
6	Solder wires 5 and 6 together and connect them to
	pin 20. Cover the solder joints with a thermofit tube.
	Leave wire 4 unconnected.
7	Tape all remaining loose ends, or seal them with a
	thermofit tube.
8
	Attach the plastic cover back on.

5.2 Connecting the Printer to the Computer

Check that the power of both the printer and the computer is switched off.

1	Discharge yourself of static electricity by touching a
	metal object such as a doorknob.
2
	Remove the plastie cap from the printer’s RS-232C
	interface connector.
3
	Plug the printer end of the RS-232C interface cable
	into the printer’s RS-232C connector and screw it in
	place.
4	Plug the other end of the cable into the computer’s
	RS-232C interface connector.
5
	Switch on the printer’s power.

B-4