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Inconsistent Transfer of Cal Coefficients from PC to 8753D

Question asked by jtowler on Sep 12, 2007
Latest reply on Sep 12, 2007 by odanzy
I have encountered a problem trying to set calibration coefficients back into my 8753D from a computer over GPIB (doing the calibration and retrieving the coefficients work fine). If the NA has a calibration already in use (that is, it has been calibrated since the last PRESET, leaving that calibration in what I assume is volatile memory, not stored in a register), transferring the coefficients does not work properly: the resulting measurements have clearly not been calibrated (at least, not with the values I just sent; instead, it appears to be some reproducible combination of the calibration already in there and the values I sent). 
If I PRESET the NA, then run my program, the instrument correctly accepts the values and the measurement runs smoothly. This makes me think that the problem is overwriting the data already in use, not in the transfer itself. So I suppose an option is to issue "RST;" before transferring cal data, but this is not mentioned in any of the examples (specifically, Section 5 of the Programming Guide). 
I am coding in C++, and the code itself is too complex to quote here, but the relevant GPIB strings sent are the following: 
    Set up measurement parameters
    These are the same parameters used during calibration 
    lots of calibration data in correct ASCII form 
*OPC?;NUMG 10; 
I appreciate whatever suggestions y'all have. Thanks.