13 Sep
1999
13 Sep
'99
1:41 p.m.
On Mon, 13 Sep 1999, Tony Duell wrote:
> The best (only?) low level reference to HP_IL
is "The HP-IL System: An
> Introductory Guide to the Hewlett-Packard Interface Loop" by Kane, Harper
> and Ushijima published by Osbourne/McGraw Hill. It is (was?) available
> through any book store. It's manadatory if you're interested in low level
> details about HP-IL.
Joe: I've found that the original HP specs document by HP is more explicit
about all hardware aspects, and more to the point. However, I must say
that I learned most that I know about _programming_ the HPIL from
Kane et al.
The HPIB is a kludge :-). The basic instrument is HPIL, and the HPIB
board is a microcontroller + ROMs + 1LB3 + interface parts. There's a 4
pole changeover switch that links the HPIL port on the main board either
to the external connector or to the HP-IL port on the HPIB card. That
card then translates HPIB commands/data into HPIL ones -- sort of like a
special 82169.
Tony: I would not call it a kludge. According to HPIB instrument design
standards, the computer communications should be electrically isolated from
the instrument's electronics. In the particular case of the 3421, using
the intrinsic electrical isolation provided by the HPIL loop's pulse
xformers to fulfill this requirement is actually sensible cost-conscious
engineering.
Best regards,
Carlos.