Agilent Technologies E1437A User Manual page 99

20 msample/second adc with filters and fifo

Table of Contents

E1437A User's Guide

VXI plug&play Programming Reference

hpe1437_read_raw

Reads raw, unscaled data from FIFO

VXIplug&play Syntax

#include "hpe1437.h"

ViStatus hpe1437_read_raw(ViSession id, ViInt16 rec[ ], ViInt32 wordCount);

Description

hpe1437_read_raw returns a block of raw, unscaled data from the FIFO.

This function can only read data from the VME backplane register. The data port of the

E1437 must be set to HPE1437_VME by the hpe1437_data_port function for this

function to be effective.

Parameters

id is the VXI instrument session pointer returned by the hpe1437_init function.

rec is a pointer to the array into which the raw data record is to be place. Be sure to

allocate sufficient storage space to hold the full data record as determined by the

wordcount parameter.

wordCount is the number of short data values to read into the data array from the

E1437 output FIFO. The maximum wordcount depends on the blocksize, data type, data

resolution, and appendStatus parameter settings according to the following formula:

maxwordcount= W × blocksize + A

where W-=1 for 16-bit real data, W=2 for 32-bit real data, W=2 for 16-bit complex data,

W=4 for 32-bit complex data. A=1 if append ADC status is turned on, or A=0 if append

ADC status is off. In continuous data collection mode or when append ADC status is

turned on, wordcount should be set equal to maxwordcount to ensure that the entire

data block is read out and that the last word corresponds to appendStatus.

NOTE

The primary purpose of the hpe1437_read_raw function is to provide the fastest

possible way to read blocks of data from the module. It reads data regardless of

the instrument state, whether a block of data is available or not. The resulting

data ordering is dependent on the data type and resolution. The array may be

cast as a long before reading the data to provide whole words.

Effect on Active

This command does not abort any measurement in progress when any parameter value

Measurement

is changed.