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From: k@hprnd.rose.hp.com (Steve Kao)
Newsgroups: comp.sys.hp
Subject: Re: How can I turn on Xon/Xoff if HPGL plotter
Message-ID: <2630009@hprnd.rose.hp.com>
Date: 20 Jun 91 17:32:12 GMT
References: <3471@unccvax.uncc.edu>
Organization: HP Roseville Networks Division
Lines: 33

Wen-Shiang Chin posts:
> 	I have a HP Prodraft DXL plotter was connected a HP 300
> workstation running HP-UX 7.05. It works perfectly. Recently,
> I bought a sony NEWS laptop 3250 runnign NEWS-OS 5.01 and connect
> the plotter directly to the sony machine. I ported my old hpgl files
> from HP machine to sony machine and try to plot them out; but it seems not
> work properly. I read the sony document and it says the data flow is
> using a Xon/Xoff handshaking method. My question is how can I
> set the Xon/Xoff on within the hpgl file. My hpgl files was generated
> by C program. Can someone tell me how can write this routine in
> C. Or, there may be another reason cause that plotter works unproperly.
> Do I need a printer filter for the plotter? Any suggestion will
> be appreciated!

The way Xon/Xoff handshaking works is when the receiver's buffer starts
to get full, it transmits an XOFF byte (a DC3 in ASCII, or 0x013).  When
the receiver's buffer becomes more empty, it transmits an XON (a DC1 in
ASCII, or 0x011).  This is usually handled at the driver level.  The
plotter's serial driver transmits the Xon/Xoff bytes, and the computer's
serial driver stops transmitting when it sees an XOFF and resumes when
it sees an XON.

From what you're describing, it sounds like your plotter is not
configured for Xon/Xoff.  If not, it must be using a hardware handshake
while talking to your HP workstation.  You should get a plotter manual and
see how to configure it for Xon/Xoff.  Perhaps you could reconfigure
your Sony for hardware handshaking?

You cannot turn on Xon/Xoff within your hpgl file.  Xon/Xoff is handled
at the driver levels within the computer and the plotter.

Good luck,
- Steve Kao