Re: HPIB bus commands

From: Greg King (
Date: 2004-04-18 07:30:39

From: Larry Mollica; on Date: Monday, April 12, 2004, at 03:57 PM
> I'm wondering if anyone has experience with, or knows of a source of
> information regarding, using the PET to control Hewlett Packard test
> equipment.
> I need a way to send specific "bus commands" to the HP gear.
> From what I gather, bus commands are essentially like sending regular
> data except that the ATN line is held low.  If there's a way to do this
> within PET BASIC, it has escaped me.
> There are only a few bus commands I need to send, mostly to release
> control of the instrument's front-panel.

I think that you might be confusing "bus commands" with "device commands."
TALK/UNTALK and LISTEN/UNLISTEN are bus-commands.  But, an instruction to
unlock an instrument's front-panel would be a device-command (or an

So now, the question is:
1) are device-commands sent as "normal data,"
2) or are they, too, sent with ATN set to "active."

If the answer is (1), then PRINT# probably should work.  But, if the answer
is (2), then you might be able to use BASIC's OPEN statement.

I vaguely remember that OPEN keeps ATN set to "active" while it sends the
file-name string.  If I'm correct, then you could pretend to open (and
close) a file.  You would use the device-command that you want to send as
the name of that phony file.

More questions just occurred to me:  How does Commodore's definition of
"device number" compare to Hewlett Packard's definition?  Is the CBM even
able to choose one of your instruments?!

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