HP plotters on Indy

Jane Strouse (mjs@chem.ucla.edu)
Wed, 18 Sep 1996 11:37:58 -0700

With respect to using the HP 7550a on an Indy, I have been doing it
for some time now with no problem. I find that my cable is not exactly
what John Grundy said to use (assuming that what I wrote down is really what
I did). I just winged it from looking at the Indy manual and it worked.
Mine is the same except I have:
Din-8 DB-25
===============
6 4
7 6

I actually use mine on an A/B switch so I can plot on either of 2 systems
running xwinnmr, so it could be that I have something reversed in there.
Perhaps if I knew more about such things I would realize that this makes no
difference anyway.

Another point is that when I first tried to put an HP7550a that
worked perfectly well on an Aspect 3000 onto the newer Bruker systems (at
the time an AspectStation), I found that no matter what I did, I always got
some sort of error message in the "console window" that said "Plotter
connected to device has not the specified type". After driving the people
in Bruker service nuts, I found that Clemens Anklin had the solution to this
problem (which seems not to be anywhere in the HP documentation). It turns
out that some older HP7550a's are schizophrenic. There is an internal
setting (that was not sampled by the Aspect 3000 data system) that makes it
think that it is some other kind of plotter. You can tell whether yours has
this problem with the following strange procedure.
1) Turn off the power
2) Hold down ENTER and pen 6 simultaneously while turning on the
power switch
(Obviously, you would have tried this, right?)
3) The small liquid crystal display should say:
HEWLETT-PACKARD
7550A, 15 2
4) If everything is OK, turn the power off then back on again.
Otherwise, see below.

If it does not think that it is a HP7550a, then you can perform a
personality transplant with the following:
1) Press ENTER, & get the message:
PRESS ENTER TO CONFIRM n (where n is a number that needs
to be 2)
2) Press 2 then ENTER
3) Press ENTER again to confirm it.
4) The display should then change to the correct message.
5) Turn the power off then back on again.

Even with the appropriate cable and internal identification, don't forget
that the configuration dialog must also be correct. I got mine from the old
uxnmr manual page 178. That is:
Configuration dialogue: SERIAL
MONITOR MODE: OFF
DATA FLOW: REMOTE; STAND ALONE
BYPASS: OFF
HANDHAKE: XON/XOFF; DIRECT
DUPLEX: HALF
PARITY: 8 BITS; OFF
BAUD RATE: 9600

Given that you have taken all the above into account, selecting
hp7550a in the cfpp and choosing the appropriate port (I use ttyd1 with the
connector on the upper of the two serial ports), the HP7550a plotter should
work fine.


Jane Strouse
Dept. of Chemistry & Biochemistry
UCLA
Los Angeles, CA 90095-1569
(310)-825-9841
(310)-825-0393 FAX
strousej@chem.ucla.edu