4.Packed Reading Conversion Formula. The equation for converting packed readings to voltages is:

readingvoltage = (readingpacked / 16) * reading resolution

The reading resolutions, which are a function of the signal range, are listed in Chapter 3 in the section "Converting Packed Readings".

VME Bus Data Transfers

The following programs demonstrate:

how post-arm readings are transferred from the digitizer’s A/D converter directly to the VME bus (VME_REAL.C)

how segmented readings (pre- and post-arm) are transferred from the digitizer’s A/D converter directly to the VME bus (VME_SEG1.C)

how segmented, 32-bit readings (channel 2 and channel 1 combined) are transferred from the A/D converter to the VME bus

The system configuration on which programs VME_REAL.C and

VME_SEG1.C were developed is listed on page 1-10.

VME_REAL.C

/* VME_REAL.C - This program reads data directly from the digitizer’s A/D */

/* converter and places it on the VME (VXI data transfer) bus. Each time the */ /* digitizer’s data register is accessed, a measurement is triggered and the */ /* reading is transferred to the VME bus during the same reading cycle. */

/* Include the following header files */

#include

<stdio.h>

 

#include

<stdlib.h>

 

#include

<string.h>

 

#include

<malloc.h>

 

#include

<cfunc.h>

/* This file is from the HP-IB Command Library */

#define ADDR 70905L

/* I/O path between the digitizer and PC */

#define CMD_MOD 70900L /* I/O path between the digitizer and the Command Module */

Continued on Next Page

Chapter 2

Using the Digitizer 63

Page 63
Image 63
HP E1429A manual VME Bus Data Transfers, Vmereal.C