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From: shiva@well.UUCP (Kenneth Porter)
Newsgroups: comp.laser-printers
Subject: Re: NEC LC890 Pageprinter Shortcomings
Message-ID: <9007200324.AA07415@crayola.cs.UMD.EDU>
Date: 18 Jul 90 18:48:42 GMT
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Frank Borriello writes:
 
 > If you use a computer which expects to see RS-232 (notably
 > SUN!) the [LC890] printer will be invisible and no flow
 > control signals will be perceived. [The NEC LC890 RS-232 port
 > is] in fact ... a TTL port where the signals vary from 0 to +5V
 > and not -6V to +6V as RS-232 stipulates.
 
I use an LC890 connected to my Sun 386i serial port with no
problems. I haven't taken a DVM to the connector to see what
the levels are, but my breakout box with two-color LEDS turns
both red and green, suggesting both positive- and
negative-going signals.  I run the printer at 19200 baud,
xon/xoff, and only occasionally hang the Sun serial port if my
workstation gets too busy and drops an xon from the printer
(the lpd daemon goes into infinite input wait waiting for the
printer to send the xon and I have to reboot to clear the
condition).  I expect that if I were willing to put up with
9600 baud (Sun's official rating for the port), there would be
no I/O errors at all.
 
I did have trouble trying to run the printer in DTR/DSR mode
(cross-wiring DTR to the Sun's CTS and DSR to RTS), but this
didn't appear to work, and I've seen comments that RTS/CTS is
only supported in one direction on Suns so I assumed that was
the source of the problem.
 
Ken (shiva@well.sf.ca.us)