Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!uw-beaver!rice!sun-spots-request
From: hysell@kodak.com (John Hysell)
Newsgroups: comp.sys.sun
Subject: Re: hp plotter
Keywords: Hardware
Message-ID: <31@brazos.Rice.edu>
Date: 6 Jul 89 12:13:26 GMT
Sender: root@rice.edu
Organization: Sun-Spots
Lines: 16
Approved: Sun-Spots@rice.edu
X-Sun-Spots-Digest: Volume 8, Issue 63, message 6 of 14

It sounds like you don't have any hardware flow control between the
plotter and the computer.  At 9600 baud you will fill up the Plotter's
on-board buffer pretty quick, and then overrun it.  Once it is overrun,
the plotter cannot handle the 'garbage' that it finds in the buffer.
(HPGL is very particular about command order.)

The best solution is to modify your cable to implement XON/XOFF flow
control (or some other protocol).  A simpler way to handle the problem
without making up a custom cable is to slow down the baud rate to a point
where the buffer is not exceeded.  Start at 150 baud, and gradually bump
it up until you start blasting the buffer again, then back it down a notch
or two.  The 'optimal' baud rate will be hard to settle on as the plotter
will print at varying speeds depending on the size and position of the
text in your files.

Hope this helps...