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From: tschutte@isis.cs.du.edu (Tom Schutter)
Newsgroups: comp.periphs.printers
Subject: SparcStation & HP LaserJet III
Message-ID: <1991Mar12.031651.16321@isis.cs.du.edu>
Date: 12 Mar 91 03:16:51 GMT
Organization: Nyx -- Public access Unix, U. of Denver, dept. of Math/CS
Lines: 26


I am trying to hook up a HP LaserJet III to a Sun SparcStation
and I have a few questions.
 
The Sun doc says that "Sun serial ports have RS-232-C cabling
conventions, but use RS-423 signaling."
The LaserJet III doc says that the printer can be configured for RS-422A.
 
I have successfully connected the SparcStation to an IBM-PC
with a null-modem cable and have had no problems. I was blissfully
unaware of the "RS-423 signalling."
I have been partially successful connecting the SparcStation
to the LJ-III. Apparently I have one-way communication from
the SparcStation to the LJ-III. But the LJ-III cannot send
x-on and x-off signals back to the SparcStation. Setting the
baud rate to 1200 results in a slow but workable solution.
 
The LJ-III doc indicates that both RS-232-C and RS-422A use
pin 3 to receive data, but with RS-422A, the signal is "inverted".
 
Questions:
Why did the null-modem cable to the PC work?
How do the RS-422 and RS-423 standards relate?
What would be the correct cable between the SparcStation and the LJ-III?
Thanx,
Tom