[time-nuts] Wavecrest DTS 2070 GPIB access

[John Miles]

I've tried a few variations on EOI/EOS behavior.  It's definitely not
sending either EOS characters or asserting EOI in the cases where the
timeout occurs... it's just not sending anything at all in those cases.
ibcntl=0, indicating no traffic arrived at all.

It seems that the DTS just doesn't like asynchronous queries.  I eventually
ran across an app note that indicates the need to serial-poll the
instrument, waiting for a message-available flag before addressing it to
talk.  That will most likely take care of the issue, I'm hoping...

-- john, KE5FX

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of Ulrich Bangert
> Sent: Tuesday, November 23, 2010 9:49 AM
> To: 'Discussion of precise time and frequency measurement'
> Subject: Re: [time-nuts] Wavecrest DTS 2070 GPIB access
>
>
> John,
>
> I do not have any experience with the Wavecrest but my experience with
> devices that do not seem to answer on bus requests is that they often DO
> ANSWER the request but after the answer they do not serve the
> bus's EOI line
> correct. Checking the EOI line is the standard way that the controller
> checks the presence of an answer with. For me this was the case at least
> with a HP3457 multimeter as well as a R&S URV 5 rf power meter.
>
> If you use a NI compatible plugin card with the accompanying DLL
> you should
> make yourself a debugging aid that enables you to display the contents of
> the input buffer (the one you give the pointer to the dll for a read call)
> in case of timeout. For me usually the correct answer  was to be found in
> the input buffer despite the timeout. That was the reason why I
> switched my
> EZGPIB communication completely from EOI to EOS. Even the instruments that
> do not serve the EOI line correct seem to send a correct string
> termination
> as <CR> or <LF>.
>
> 73s de Ulrich, DF6JB
>
> > -----Ursprungliche Nachricht-----
> > Von: time-nuts-bounces at febo.com
> > [mailto:time-nuts-bounces at febo.com] Im Auftrag von John Miles
> > Gesendet: Dienstag, 23. November 2010 11:27
> > An: time-nuts at febo.com
> > Betreff: [time-nuts] Wavecrest DTS 2070 GPIB access
> >
> >
> > I'm looking at writing some code to drive the DTS 2070, but
> > have been running into timeout errors performing any GPIB
> > query (even *IDN?) while the instrument is taking
> > measurements, even in sizes/sets of 1/1 at a 1-pps rate.  Has
> > anyone else run into this before?
> >
> > This happens equally with either a Prologix GPIB-USB adapter,
> > or an NI PCI-GPIB board, both of which are otherwise reliable.
> >
> > -- john, KE5FX
> >
> >
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