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Issue retrieving trace from the E5071B using CALC:DATA:FDAT?

Question asked by zeke.steer on Aug 15, 2011
Latest reply on Aug 18, 2011 by zeke.steer
Hi all,

I'm hoping for some help on an issue which has stumped me for the past few days. 

I'm controlling an E5071B network analyser via a National Instruments USB-GPIB interface.  I'm using the National Instruments VISA libraries with Visual Studio 2008 Professional (for development) and the National Instruments Measurement & Automation software (for supplying SCPI strings to the instrument for testing).  The E5071B is running firmware rev. A.06.91.

I'm able to successfully communicate with the instrument through the VISA API in Visual Studio and using the Measurement & Automation software.  However, when I supply the query "CALC1:DATA:FDAT?", only a small proportion of the trace data (typically 405 of 1600 data points) is returned.  Moreover, when I issue the next command, the instrument reports an error: -410 or -420, Query Interrupted.

For my application, I need to retrieve the full 1600 data points.  So my questions to this forum are:
- Should the CALC1:DATA:FDAT? query return all 1600 data points?  Or is there a limit on the number of data points which can be returned?
- If CALC1:DATA:FDAT? should return all 1600 data points, then what could be causing it to return much fewer? 

Thanks in advance for any help on this issue,