meiFilterPostfilterSectionGet

meiFilterPosfilterSectionGet

Declaration

	long meiFilterPostfilterSectionGet(MPIFilter filter, long sectionNumber, MEIPostfilterSection *section);
	Required Header: stdmei.h

Description

meiFilterPostfilterSectionGet reads the configuration of a single section of an MPIFilter object's postfilter. It writes to *section the configuration of filter's postfilter sectionNumber^th section.

The MPI calculates the post filter coefficients and takes into consideration the sample rate of the controller at that time. If you change the sample rate of the controller, you will need to recalculate the post filters. This can be done for all filters specified in Hertz by setting the filters again with the MPI. The MPI will calculate the filters using the current servo sample rate.

Postfilters are used to digitally filter the output of a control loop. One common use for postfilters is the compensation of system resonances.

filter	the handle of the MPIFilter object whose postfilter section configuration is to be read.
sectionNumber	the index of the postfilter section whose configuration is to be read.
section	the data location where the postfilter's current section configuration data will be written.

Return Values
MPIMessageOK
MPIFilterMessageCONVERSION_DIV_BY_0
MPIFilterMessageSECTION_NOT_ENABLED
MPIFilterMessageINVALID_FILTER_FORM

Sample Code


/*   Test a section of a MPIFilter object's postfilter to 
     see if it is a notch type. 
     Sample usage:   

     returnValue =        
         isSectionTypeNotch(filter, 0, &isNotch);
*/
long isSectionTypeNotch(MPIFilter filter, long sectionIndex, long* isNotch)
{
    MPIFilterConfig config;    
    MEIPostfilterSection section;    
    long returnValue = (isNotch==NULL) ? MPIMessageARG_INVALID : MPIMessageOK; 

    if (returnValue == MPIMessageOK)    
    {        
        returnValue =            
            meiFilterPostfilterSectionGet(filter, sectionIndex, §ion);
        if (returnValue == MPIMessageOK)        
        {            
            *isNotch = (section.type == MEIFilterTypeNOTCH) ? TRUE : FALSE; 
        }    
     }    

     return returnValue;
}