Agilent Technologies VXI E1439 - Manual (Page 170)

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Agilent E1439 Programmer's Reference
Functions listed alphabetically
Parameters
id is the VXI instrument session pointer returned by the age1439_init function.
data is a pointer to the array into which the floating point data is to be placed. Be sure to allocate
sufficient storage space at this location to hold the full data record as determined by the
sampleCount parameter. Note that when the module is set to complex data type, the output data
record contains 2 × sampleCount floating point values. For real data the record contains
sampleCount floating point values.
sampleCount for age1439_read sampleCount is the number of real or complex data values to read. Real data is
one 32-bit floating point value. Complex data is made up of two 32-bit floating point values
comprising the real and imaginary values.
for age1439_read64 sampleCount is the number of real or complex data values to read. Real data
is one 64-bit floating point value. Complex data is made up of two 64-bit floating point values
comprising the real and imaginary values.
This should never be set larger than the blocksize parameter set in the age1439_data_blocksize
function. In continuous data collection mode, sampleCount should be set equal to blocksize to
ensure that the entire data block is read out.
overloadPtr returns an overload indicator. The way to properly use the overload argument for the age1439_
read or age1439_read64 function is this:
1. Set up the hardware.
2. Call
age1439_meas_start .
3. Call age1439_read or age1439_read64 .
If data is not available, the read function returns immediately with one of the following return values, and
the overload indication is
AGE1439_OFF :
AGE1439_NO_DATA_MEASUREMENT_IN_PROGRESS
AGE1439_NO_DATA_MEASUREMENT_PAUSED
AGE1439_NO_DATA_WAITING_FOR_TRIGGER
AGE1439_NO_DATA_WAITING_FOR_ARM
When data is available, AGE1439_SUCCESS is returned and the overload value reflects whether an
overload was encountered for the given data block.
4. In continuous mode, subsequent data blocks can be read by calling a age1439_
read or age1439_read64 function again ( age1439_meas_start should not be called
again).
5. When used in this way, an overload indication is given for each and every
data block read in block mode. In continuous mode the overload indicator
only means there was an overload sometime after calling
age1439_meas_start .
Comments on Overload
Since reading the status register clears the overload bit, overloads are tracked at the API level.
In block mode, you receive the overload indication on a block-by block basis by calling age1439_
meas_start and age1439_read in sequence.
In continuous mode, depending on the effective sample rate of the instrument and how often data
is read, an overload indication returned by age1439_read may or may not correspond to the data
returned. The overload indication only means that an overload has occurred since the most recent