[mod.computers.laser-printers] HP to AT comm

mlw@NCSC.ARPA.UUCP (03/27/87)

Thomas:

You may be suffering from a handshaking problem.  If you are running
with DTR hardware handshaking at a high (9600-ish) baud rate, you may
lose characters due to one being in route (from the PC's perspective)
when the printer drops DTR.  There's no way for the computer to know
whether or not the last transmitted character was received or not.
Possible solutions include (1) using a print utility that uses XON/
XOFF and changing the LaserJet to using that handshake, (2) putting
a printer buffer in the line, and (3) lowering the transmission speed.
The setup I had used (2) -- we have a Printer Optimizer (256K) from
Applied Creative Technology that has performed excellently.  I hope 
this info is accurate and helps.  Good luck.

Mark L. Williams
(mlw@ncsc.arpa)

P364@QZCOM.BITNET.UUCP (03/30/87)

We use xon/xoff and 19200 and never lose a single bit transferring
data from our HP9000/540 computer to the Laserjet+.

bam@bigbang.UUCP.UUCP (03/31/87)

The symptoms you describe do sound like a handshaking problem.

Assuming that your cable has been built properly, the AT or XT
will drive the Laserjet just fine with X-ON/X-OFF flow control.

IF your printer is on com1:

MODE COM1:96,n,8,1,p

will configure the serial port correctly.  The 'p' sets the port
for printer handshaking.

If that still doesn't work, check the switches inside the printer
and make sure everythng is set as per the factory.

Now if that doesn't help, send me a private note and I'll send
you cable pinouts.  I tried to reply directly but my mail bounced
as undeliverable.

Bret Marquis
bam@bigbang.cts.com