note patcat88 Hmmmm. Not an Perl OLE expert, but, it seems GetPrecursorInfoFromScanNum returns a Variant array of C structs, not an variant array of integers according to the manual. Every example in the manual is C/C++, zero VB. Is your <code> "Output: $VAR1 = [ '414.005279541016', '1.83302424514875e-307', '3.50253979763967e-310', '1.36817960845299e-312', '2.68156223007842e+154', </code> even valid compared to Thermo's official viewer for the file? <br><br> I think you need to try to get perl OLE to return an array of string, the strings will be binary garbage but should be 8+8+4+4 bytes long, then do an "unpack('FFll',$arr[[$i]]);" on it to decode the C struct. Try looking for Visual Basic code for your control and see how its done there. <code> typedef struct tagMS_PrecursorInfo { double dMonoIsoMZ; double dIsolationMZ; long nChargeState; long nScanNumber; } MS_PrecursorInfo; </code> I pulled that from the IDL inside your control. Its described the same way in manual page for GetPrecursorInfoFromScanNum. Can you point me to a sample raw file for this control? <br><br> Edit, try changing "my $arr = Variant( VT_VARIANT | VT_BYREF);" to " my $arr = Variant( VT_ARRAY | VT_BYREF);" 935769 935769