Hi All,
I am trying to collect data from an oscilloscope using Visa programming. I have modified the existing program examples bufferio.cpp and formatio.cpp. When I use the viScanf function, it does not succeed and reports me error. I am attaching the modified code that I use.
double* ReadWaveform(ViSession vi, long* elements)
{
ViStatus status;
float yoffset, ymult;
ViChar buffer[256];
ViChar c;
long count, i;
double* ptr = NULL;
unsigned char szBuff[256] = { 0,};
static ViUInt32 Wrcount;
static char stringinput[512];
assert(elements != NULL);
status = viSetAttribute(vi,VI_ATTR_WR_BUF_OPER_MODE, VI_FLUSH_ON_ACCESS);
status = viSetAttribute(vi,VI_ATTR_RD_BUF_OPER_MODE, VI_FLUSH_ON_ACCESS);
/* Set the timeout for message-based communication*/
status = viSetAttribute(vi, VI_ATTR_TMO_VALUE, 25000);
strcpy(stringinput,"MEASUREMENT:IMMED:SOURCE1 CH3");
status = viWrite (vi, (ViBuf)stringinput, (ViUInt32)strlen(stringinput), &Wrcount);
if (status < VI_SUCCESS)
{
printf("Error writing to the device\n");
goto error;
}
// Turn headers off, this makes parsing easier
status = viPrintf(vi, "header off\n");
if (status < VI_SUCCESS)
{
printf("Error writing Header off to the device\n");
goto error;
}
// Get record length value
status = viQueryf(vi, "hor:reco?\n", "%ld", elements);
printf("The number of elements is %ld \n",*elements);
if (status < VI_SUCCESS)
{
printf("Error getting the elements value\n"); WORKS FINE
goto error;
}
// Make sure start, stop values for curve query match the full record length
status = viPrintf(vi, ":data:start 1;:data:stop %d\n", *elements);
if (status < VI_SUCCESS)
{
printf("Error writing start and stop values\n");
goto error;
}
// Get the yoffset to help calculate the vertical values.
status = viQueryf(vi, "WFMOutpre:YOFF?\n", "%f", &yoffset);
printf("The yoffset value is %f \n",yoffset); WORKS FINE
if (status < VI_SUCCESS)
{
printf("Error getting the yoffset value\n");
goto error;
}
// Get the ymult to help calculate the vertical values.
status = viQueryf(vi, "WFMOutpre:YMULT?\n", "%f", &ymult); WORKS FINE
printf("The ymult value is %f \n",ymult);
if (status < VI_SUCCESS)
{
printf("Error getting the ymult value\n");
goto error;
}
// Request 8bit binary data on the curve query
status = viPrintf(vi, "DATA:ENCDG RIBINARY;WIDTH 1\n");
if (status < VI_SUCCESS)
{
printf("Error writing the encoding width value to the device\n");
goto error;
}
// Request the curve
status = viPrintf(vi, "CURVE?\n");
if (status < VI_SUCCESS)
{
printf("Error writing CURVE to the device\n");
goto error;
}
// Always flush if a viScanf follows a viPrintf or viBufWrite.
status = viFlush(vi, VI_WRITE_BUF | VI_READ_BUF_DISCARD);
if (status < VI_SUCCESS)
{
printf("Error writing Flush to the device\n");
goto error;
}
// Get first char and validate
status = viSetAttribute(vi,VI_ATTR_RD_BUF_OPER_MODE, VI_FLUSH_DISABLE);
status = viScanf(vi, "%c", &c); ERROR HERE
if (status < VI_SUCCESS)
{
printf("Error Setting attribute and getting a char \n"); PRINTING THIS MESSAGE
goto error;
}
assert(c == '#');
// Get width of element field.
status = viScanf(vi, "%c", &c);
if (status < VI_SUCCESS)
{
printf("Error getting width of element from the device\n");
goto error;
}
assert(c >= '0' && c <= '9');
// Read element characters
count = c - '0';
for (i = 0; i < count; i++)
{
status = viScanf(vi, "%c", &c);
if (status < VI_SUCCESS)
{
printf("Error reading element characters from the device\n");
goto error;
}
assert(c >= '0' && c <= '9');
}
// Read waveform into allocated storage
ptr = (double*) malloc(*elements*sizeof(double));
for (i = 0; i < *elements; i++)
{
status = viScanf(vi, "%c", &c);
if (status < VI_SUCCESS)
{
printf("Error writing to the device\n");
goto error;
}
ptr[i] = (((double) c) - yoffset) * ymult;
fprintf(fp,"%c \t", ptr[i]);
}
status = viFlush(vi, VI_WRITE_BUF | VI_READ_BUF_DISCARD);
if (status < VI_SUCCESS)
{
printf("Error Flush to the device\n");
goto error;
}
return ptr;
error:
// Report error and clean up
viStatusDesc(vi, status, buffer);
fprintf(stderr, "failure: %s\n", buffer);
if (ptr != NULL) free(ptr);
return NULL;
}
What should I do to get the data using viScanf. Can somebody please help? Thanks
Ashwin
