hp plotter

Guy Harris auspex!guy at uunet.uu.net
Sun Jul 23 06:48:30 AEST 1989


>I think your problem may be with flow control - the first buffer gets sent
>properly and the HP then tries to use RTS/CST to tell the sun to wait a
>bit.  The sun ignores this and then ... The way out is to tell the HP to
>use XON/XOFF flow control (and also apply YAPT 5.??? if your running SunOs
>4.0.1).

If you're running SunOS 4.x, you might just try telling the Sun *not* to
ignore RTS/CTS flow control, by using the "ms" capability in "printcap"
and specifying "crtscts" mode.  (Note: it's unidirectional RTS/CTS flow
control - i.e., the Sun can't control flow of data *into* it - but for a
printer or plotter, that should be sufficient.  Bi-directional flow
control, unlike unidirectional flow control, requires software changes -
it can't be done just by the hardware, as unidirectional flow control can.
Note also that the ALM - i.e., the Systech MTI board, as opposed to the
Sun-built ALM-2 - *always* does unidirectional RTS/CTS flow control,
although you can tie CTS high and disable it.)



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