NI VISA Performance

[eric931]

i use VISA for PXI Card , and use viMapAddress to R/W IO 64k Times

My Code as below:

But total time divide by 64k is about 2.5uS ( when it read 64M data total need 160s  very slow)

have any method to improve performance? 

thanks.

  ViStatus status = VI_SUCCESS - 1;
  ViSession deviceRM = 0;

  status = viOpenDefaultRM(&deviceRM);

  ViSession instr = 0;
  int timeOut = 5;
  status = viOpen(deviceRM, "PXI9::15::INSTR", VI_NULL, timeOut, &instr);
 

  ViAddr memptr = nullptr;

  status = viMapAddress(instr, VI_PXI_BAR0_SPACE, 0, 0x1000, VI_FALSE, VI_NULL, &memptr);

  unsigned int* pt = (unsigned int*)memptr;
  ViUInt32 rtn = 0;

  LARGE_INTEGER m_Freq = {0};
  QueryPerformanceFrequency(&m_Freq);

  LARGE_INTEGER m_St = {0};
  QueryPerformanceCounter(&m_St);

  for(int ii=0;ii<64*1000;ii++)
  {
    unsigned int val = pt[10];
    //viPeek32(instr,pt+10,&rtn);
  }

  LARGE_INTEGER m_Sp = {0};
    QueryPerformanceCounter(&m_Sp);

    long time = (m_Sp.QuadPart - m_St.QuadPart)*1000/m_Freq.QuadPart;
  printf("NI VISA Time = %d ms\n",time);

  status = viClose(instr);
  status = viClose(deviceRM);