AnsweredAssumed Answered

vrf Vs: GPIB to LAN

Question asked by k.alexander on Apr 13, 2004
Hi
I understand that it is not "by the book"
the way I established communication.

How is it done "by the book" without
driver, with vee.

I've seen it done with labview.

Best regards

Kjeld Alexander


>
> Fra: "Brian H. Powell" <brian@ni.com>
> Dato: 2004/04/13 Tue PM 05:04:58 CEST
> Til: VRF <vrf@agilent.com>
> Emne: [vrf] RE: GPIB to LAN
>
> > I think your best bet would be to have GPIB added to the scope.  It is a
> > $400 accessory with p/n TDS3GV.  At that point you get a supported driver.
>
>      I'm not sure I understand what the original poster wants to do, so
> there are some fundamental concepts that I think are worth mentioning.
>      Most LAN-capable instruments (at least from major instrument vendors
> like Agilent and Tektronix) support VXI-11.  VXI-11 has nothing to do with
> VXI; it's just a protocol for how you send messages to and from instruments
> over TCP/IP.  VXI-11 is very similar to GPIB in that it supports reading and
> writing messages, triggering, clearing, asserting SRQ, etc.  (Can you tell
> it was defined by major instrument vendors who already invested in GPIB?)
>      NI-VISA and Agilent VISA both know how to talk to VXI-11 instruments.
> Thus, if you write a program using VISA for a GPIB interface, it will
> probably work with no modifications if you switch to a LAN interface.  (More
> on the "probably" in a moment.)  You just have to open up a different
> resource--instead of "GPIB0::22::INSTR", you open
> "TCPIP::10.0.20.30::INSTR".
>      So, I'm wondering if Jim Hetrick (the original poster) just needs to
> point his existing application at the LAN device and if it will work.  You
> should be able to send regular SCPI commands, or you could probably use the
> existing VXIpnp driver from Tek.
>      One caveat...  I have a TDS3054B with the TDS3GV option, and it speaks
> VXI-11.  I have not tried removing the TDS3GV and tested whether I can still
> use VXI-11.  I can't imagine that Tek would disable that, but you never
> know.
>      Someone else suggested you could just try to use your own socket
> connections to talk to the scope.  I would suggest that this is way more
> trouble than it's worth.  VXI-11 is based on Remote Procedure Calls, which
> is significantly more complicated than just socket reads and writes.  Use
> VISA instead.  Really.
>      A note on the "probably work with no modifications"...  Be sure you get
> the latest firmware from Tektronix and the latest VISA library you want to
> use.  I know there were some bugs in early Tek TDS 3xxx firmware revisions
> that kept SRQ from working correctly.  Also, unless you have source code to
> the driver, you never know what sort of interface-specific code might be
> going on inside the driver.  E.g., if the author had code that did low-level
> GPIB configuration, it would return an error with VXI-11.  This sort of code
> is rare (except for serial I/O), but you never know.  That's why you want
> source code for your instrument drivers.
>      Anyway, I hope this helps.  If you could be clearer what you are really
> trying to do, I think we could provide more assistance.
>
> Brian H. Powell
> Sr. Group Manager
> LabVIEW R&D
> brian@ni.com
>
>
>
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