Stanford Research Systems SR844, User Manual

Page: 137 / 246

Example Program 4-35
SR844 RF Lock-In Amplifier
// ************************************************************************
// Example program using Microsoft C v7.0 and
// the Capital Equipment Corp CEC488 interface card.
// To use another interface card, modify the GPIB subroutines
// where indicated.
// The SR844 is assumed to be at address 8 (default).
// Link this object file with ieee488.lib provided by CEC
// (or the library for your GPIB card).
// ************************************************************************
// Connect the REF OUT to the SIGNAL IN
// ************************************************************************
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <conio.h>
#include <math.h>
#include <ieee-c.h>
// This is the CEC header file
// Use the .h file for your interface card.
// send(), enter(), transmit(), rarray(), tarray(),
// spoll(), initialize(), settimeout() are routines
// defined in ieee-c.h.
// ************************************************************************
#define
sr844 8 // address of SR844
int status, length; // CEC routines use these
char recv[80]; // global GPIB receive string
char cmd[80]; // global GPIB command string
int FastBuf[1600]; // Fast Transfer Mode buffer (2 ints per point, X&Y)
int rLiaBuf[1600]; // LIA float buffer (ch1) (2 ints per point)
int pLiaBuf[1600]; // LIA float buffer (ch2) (2 ints per point)
float rfBuf[800]; // IEEE binary buffer (ch1) (1 float per point)
float pfBuf[800]; // IEEE binary buffer (ch2) (1 float per point)
char rAscBuf[10][20]; // ASCII string buffer (ch1)
char pAscBuf[10][20]; // ASCII string buffer (ch2)
double fscale[15] = {1.0E-7, 3.0E-7, 1.0E-6, 3.0E-6, 1.0E-5, 3.0E-5, 1.0E-4, 3.0E-4,
1.0E-3, 3.0E-3, 1.0E-2, 3.0E-2, 1.0E-1, 3.0E-1, 1.0};
// array of full scale sensitivities in Volts
int sens; // sensitivity number [0-14]
// ************************************************************************
// Subroutines at the end of this listing
// ************************************************************************
// GPIB interface subroutines
// You may need to modify these for your interface card!
void TxGpib (int, char *); // transmit string to device
void GetGpib (int); // receive string from device
void TxSr844 (char *); // transmit string to SR844, wait for IFC
void GetSr844 (char *); // transmit query string to SR844 (wait for IFC),
// and get receive string
void WaitIFC (void); // wait for IFC status in SR844 (command complete)
// ************************************************************************
void GetSpace (void); // pause and wait for space bar
double xLIA (int,int); // translate LIA float data to real values
double xBin (int,int); // translate IEEE binary data