Re: data copy (fwd)

["Steven E. Williamson" <sew@npl.uiuc.edu>]

Dear Fred and Peter,

We used the multiplexed DMM before it was sent to PSI for a number
of months.  It was interfaced first with the GPIB connection,
but later we switched to the RS-232 connection (because we moved
the instrument to a computer without GPIB).  We NEVER had any
trouble with the RS-232 interface.  As you are no doubt aware,
RS-232 is not a particularly standardized standard.  Of course
you have to get the port parameters right (parity, no. of data
and stop bits, baud rate, etc.)  And  it is VERY important that you get 
the cable right (normal versus "null-modem" cable configuration).  Are you
using the cable that came with the instrument?  (it is black).
That one worked fine when connecting a 9-pin PC serial port
to the instrument and it was returned with the DMM.  What are you using to 
send/receive characters?

We used LabView 7.1 to talk to this instrument.  If you are interested,
I can send the "virtual instrument" program that we wrote.  I think
most of bottom-level I/O was handled by a library of "VIs" for the
instrument that we downloaded from National Instruments "developer
zone".

The "isolator failed" message is a little worrysome.  Any idea
what this means?

I hope this helps.


On Tue, 30 Aug 2005, Peter Kammel wrote:

> Dear Steve,
>
> Can you help on that and send Fred some info
> about your experience.
>
> Thanks
>
> Peter
>
>
>
> ---------- Forwarded message ----------
> Date: Tue, 30 Aug 2005 07:40:25 -0700
> From: Frederick Gray <fegray@berkeley.edu>
> To: Peter Kammel <kammel@npl.uiuc.edu>
> Subject: Re: data copy
>
>> Thanks. In again other news, I sent the Agilent 20 channel
>> DVM. If you have a chance to talk to it, that would be great,
>> because we need it for the chamber current protection circuitry.
>
> Hi, Peter,
>
> I think there is something wrong with the RS-232 interface on the new DMM.
> Generally, it seems to know when you're typing, and it beeps at you when you
> make an obvious syntax error.  However, it doesn't respond to commands,
> including simple ones like "DISP OFF", "DISP:TEXT "blah"", "SYST:VERS?",
> or "*RST".
>
> When you run a complete self-test (holding down the shift key while turning
> on the power), it sends "ISOLATOR FAILED" to the RS-232 port, but it shows
> "PASS" on the display.  "ISOLATOR FAILED" is the only thing I have seen
> it transmit at any time.  Did you test the readout at all in Illinois?
>
> Thanks,
>
> -- Fred
>
> -- Fred Gray / Visiting Postdoctoral Researcher                 --
> -- Department of Physics / University of California, Berkeley   --
> -- fegray@berkeley.edu / phone 510-642-2438 / fax 510-642-9811  --
>