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*IDN? returns invalid with DSO3202A and AIOLv15

Question asked by bbledsoe on Mar 31, 2008
Latest reply on Apr 14, 2008 by bbledsoe
I'm using Agilent IO Libraries v15 to control a DSO3202A via the
USB/GPIB interface (model 82357B) and the N2861A extension module.

The AIOLv15 Connection Expert recognizes the scope both via RS232
and as a GPIB device (not at the same time of course). I can also see
the correct ID string in the Connection Expert software...


As you can see, the scope has the latest 4.02.15 firmware.

Unfortunately, my C program which uses the "visa32.dll" to control the
scope cannot read back a valid ID string using the "*IDN?" command.

When the plain RS232 interface is used, the first byte times out so that no
characters are read back. Unplugging that cable and using the USB/GPIB
interface does read back some data, but it appears that every other
character is skipped...


Experimentally, I also tried reading 2 bytes per viRead() call and the
resulting string appears to skip every third character...


And reading back 4 bytes per viRead() call appears to skip every
5th character...


To debug this problem, I attached the simple C command-line program
(written and tested in Visual Studio 2005) which demonstrates the above

Any ideas, Agilent IO Lib experts? I've controlled Agilent and Tek scopes
via C/C++ programs for many years using the VISA library calls. But I'm
really stumped by this one.