/*	**************************************************************  */
/*
 *	Module LS450
 *	This module contains I/O functions for the Lake Shore 450 teslameter.                 
 *
 *	Zachary Wolf
 *	1/26/00
 */ 

/*	**************************************************************  */

/*	INCLUDES  */
#include <utility.h>
#include <gpib.h>
#include <formatio.h>
#include <ansi_c.h>
#include "ls450.h"

/*	**************************************************************  */

/*  PRIVATE FUNCTIONS  */
int ls450_open_dev(int gpib_board_addr, int gpib_dev_addr);
void ls450_close_dev(int dev_ID);
int ls450_check_dev_open(int dev_ID);
int ls450_out(int dev_ID, char* buf);
int ls450_in(int dev_ID, char* buf);
int ls450_spoll(int dev_ID, int* spoll);
void ls450_wait_until_not_busy(int dev_ID);
void ls450_wait_until_data_ready(int dev_ID);
int ls450_get_errors(int dev_ID);
void ls450_message(char* msg);
void ls450_error(char* msg);

/*	**************************************************************  */

/*  PRIVATE DEVICE TABLE  */
/*
 *	This table allows several devices of the same type to be
 *	used in the system.
 *  dev_addr, contains the GPIB addresses of opened devices
 *  dev_descr, contains the device descriptors of opened devices
 *  dev_count, contains the number of devices open of this type
 */
static int dev_addr[LS450_MAX_NUM_DEV + 1];
static int dev_descr[LS450_MAX_NUM_DEV + 1];
static int dev_count;

/*	**************************************************************  */

/*  PRIVATE GLOBAL VARIABLES  */
/*
 *  cmd, buffer for GPIB I/O strings
 *  msg, buffer for message strings to Standard I/O
 */
static char cmd[LS450_MAX_CMD + 1];
static char msg[LS450_MAX_CMD + 1];

/*	**************************************************************  */

/*	PUBLIC FUNCTIONS  */

/*	**************************************************************  */
/*
 *  ls450_init
 *  This function opens the device, queries for ID, and
 *  initializes the device to a known state.
 *
 *	Input:
 *	gpib_board_addr, address of the GPIB board the device is connected to (0, 1, ...)
 *	gpib_dev_addr, GPIB address of the device (1 to 30, 0 is reserved)
 *
 *	Output:
 *	dev_ID, identifier for future references to the device
 *
 *	Zachary Wolf
 *	1/26/00
 */

void ls450_init(int gpib_board_addr, int gpib_dev_addr, int* ID)
{
    /* Declare variables */
    int dev_ID;
    int err;
    int i;
    
    /* Message */
    ls450_message("");
    ls450_message("Initializing the Lake Shore 450 Teslameter...");

    /* Check input parameters */
    if (gpib_board_addr < 0 || gpib_board_addr > 10)
    {
    	Fmt(msg, "%s<gpib_board_addr = %i, out of range", gpib_board_addr);
    	ls450_error(cmd);
    	return;
    }
    if (gpib_dev_addr < 1 || gpib_dev_addr > 30)
    {
    	Fmt(msg, "%s<gpib_dev_addr = %i, out of range", gpib_dev_addr);
    	ls450_error(msg);
    	return;
    }
    
    /* Exit here if testing without hardware */
    #ifdef DUMMY_DEVICES
    	*ID = 1;
    	return;
    #endif
    
    /* Open the LS450 */
    dev_ID = ls450_open_dev(gpib_board_addr, gpib_dev_addr);
    if (dev_ID <= 0)
    {
        ls450_error("LS450 was not opened");
        return;
    }
    
    /* Put the teslameter in a known default state */
    ls450_default_setup(dev_ID);

	/* Return the device ID */
    *ID = dev_ID;
    
    /* Done */
    return;
}

/*	**************************************************************  */
/*
 *	ls450_default_setup
 *  This function sets up the teslameter in a default state.
 *
 *	Input:
 *	dev_ID, device identifier
 *
 *	Zachary Wolf
 *	1/26/00
 */

void ls450_default_setup(int dev_ID)
{
	/* Declare variables */
	int i;
	int dev_open;
	int err;

    /* Check input parameters */
    if (dev_ID < 1 || dev_ID > LS450_MAX_NUM_DEV)
    {
    	Fmt(msg, "%s<dev_ID = %i, out of range", dev_ID);
    	ls450_error(msg);
    	return;
    }
    
    /* Exit here if testing without hardware */
    #ifdef DUMMY_DEVICES
    	return;
    #endif
    
    /* Check to make sure the device is open */
    dev_open = ls450_check_dev_open(dev_ID);
    if (dev_open != 1)
    {
    	ls450_error("Device not open");
    	return;
    }
    
    /* Reset the teslameter */
    ls450_out(dev_ID, "*RST");
    
    /* Set status register bits */
    ls450_out(dev_ID, "*ESE 189");		/* Standard event status register, turn on bits 0, 2, 3, 4, 5, 7 (1 + 4 + 8 + 16 + 32 + 128 = 189) */
    ls450_out(dev_ID, "*SRE 55");		/* Status byte register, turn on bits 0, 1, 2, 4, 5 (1 + 2 + 4 + 16 + 32 = 55) */
    ls450_out(dev_ID, "*CLS");			/* Clear status registers */

    /* Set interface parameters */
    ls450_out(dev_ID, "MODE 1");		/* Remote mode, but can still use front panel */
    ls450_out(dev_ID, "END 0");			/* Use EOI */
    ls450_out(dev_ID, "TERM 2");		/* Terminator LF EOI */
    
    /* Check for errors */
    err = ls450_get_errors(dev_ID);
    if (err != 0)
    {
        ls450_error("The teslameter has an error setting the interface parameters");
        ls450_close_dev(dev_ID);
        return;
    }
    
    /* Set up the teslameter */
    ls450_out(dev_ID, "ACDC 0");		/* DC measurement mode */
    ls450_out(dev_ID, "FILT 0");		/* Turn off digital filtering */
    ls450_out(dev_ID, "UNIT T");		/* Use units of Tesla */
    ls450_out(dev_ID, "MAX 1");			/* Turn on max hold */
    ls450_out(dev_ID, "AUTO 1");		/* Turn on autoranging */
    ls450_out(dev_ID, "FCOMP 1");		/* Turn on field compensation */
    ls450_out(dev_ID, "TCOMP 1");		/* Turn on temperature compensation */
    ls450_out(dev_ID, "REL 0");			/* Turn off relative mode */
    ls450_out(dev_ID, "ALARM 0");		/* Turn off alarms */
    ls450_out(dev_ID, "LOCK 0");		/* Unlock the front panel */
    
    /* Check for errors */
    err = ls450_get_errors(dev_ID);
    if (err != 0)
    {
        ls450_error("The teslameter has an error in its setup.");
        ls450_close_dev(dev_ID);
        return;
    }
    
    /* Display information to check operation */
    ls450_out(dev_ID, "*IDN?");			/* Teslameter ID */
    ls450_in(dev_ID, msg);
    printf("Teslameter ID: %s\n", msg);
    ls450_out(dev_ID, "SNUM?");			/* Probe serial number */
    ls450_in(dev_ID, msg);
    printf("Probe serial number: %s\n", msg);
    ls450_out(dev_ID, "TYPE?");			/* Probe type */
    ls450_in(dev_ID, msg);
    printf("Probe type: %s\n", msg);
    
    /* Check for errors */
    err = ls450_get_errors(dev_ID);
    if (err != 0)
    {
        ls450_error("The teslameter has an error getting display information.");
        ls450_close_dev(dev_ID);
        return;
    }
    
    /* Done */
    return;
}

/*	**************************************************************  */
/*
 *	ls450_set_range
 *  This function sets the range of the teslameter.
 *
 *	Input:
 *	dev_ID, device identifier
 *	range, range (high stability probe: 0 = 30 T, 1 = 3. T, 2 = .3 T, 3 = .03 T)
 *
 *	Zachary Wolf
 *	1/26/00
 */

void ls450_set_range(int dev_ID, int range)
{
	/* Declare variables */
	int dev_open;
	int err;

    /* Check input parameters */
    if (dev_ID < 1 || dev_ID > LS450_MAX_NUM_DEV)
    {
    	Fmt(msg, "%s<dev_ID = %i, out of range", dev_ID);
    	ls450_error(msg);
    	return;
    }
   if (range < 0 || range > 3)
    {
    	Fmt(msg, "%s<range = %i, out of range, adjusted, continuing...", range);
		ls450_message(msg);
		if (range < 0) range = 0;
		if (range > 3) range = 3;
    }
    
    /* Exit here if testing without hardware */
    #ifdef DUMMY_DEVICES
    	return;
    #endif
    
    /* Check to make sure the device is open */
    dev_open = ls450_check_dev_open(dev_ID);
    if (dev_open != 1)
    {
    	ls450_error("LS450 not open");
    	return;
    }

    /* Set the range to the requested value */
    Fmt(cmd, "%s<RANGE %i[w1]", range);
    ls450_out(dev_ID, cmd);
    
    /* Check for errors */
    err = ls450_get_errors(dev_ID);
    if (err != 0)
    {
        ls450_error("The teslameter had an error setting the range.");
        ls450_close_dev(dev_ID);
        return;
    }
    
    /* Done */
    return;
}

/*	**************************************************************  */
/*
 *	ls450_zero
 *  This function zeros all ranges of the teslameter.
 *
 *	Input:
 *	dev_ID, device identifier
 *
 *	Zachary Wolf
 *	1/26/00
 */

void ls450_zero(int dev_ID)
{
	/* Declare variables */
	int err;
	int dev_open;
	int status;

    /* Check input parameters */
    if (dev_ID < 1 || dev_ID > LS450_MAX_NUM_DEV)
    {
    	Fmt(msg, "%s<dev_ID = %i, out of range", dev_ID);
    	ls450_error(msg);
    	return;
    }
   
    /* Exit here if testing without hardware */
    #ifdef DUMMY_DEVICES
    	return;
    #endif
    
    /* Check to make sure the device is open */
    dev_open = ls450_check_dev_open(dev_ID);
    if (dev_open != 1)
    {
    	ls450_error("Device not open");
    	return;
    }
    
    /* Zero the teslameter */
    zero:
    ls450_out(dev_ID, "ZCAL");

	/* Check that the zero worked, check error bits in standard event status register */
	ls450_out(dev_ID, "*ESR?");
	ls450_in(dev_ID, msg);
	Scan(msg, "%s>%i", &status);
	if (status & (4 + 8 + 16 + 32))
	{
		printf("\nProblem zeroing the teslameter.\n");
		printf("Try again...");
		goto zero;
	}
    
    /* Check for errors */
    err = ls450_get_errors(dev_ID);
    if (err != 0)
    {
        ls450_error("The teslameter had an error during zeroing.");
        ls450_close_dev(dev_ID);
        return;
    }
    
    /* Done */
    return;
}

/*	**************************************************************  */
/*
 *	ls450_get_B
 *  This function gets the field reading from the teslameter.
 *
 *	Input:
 *	dev_ID, device identifier
 *
 *	Output:
 *	B, field reading (T)
 *
 *	Zachary Wolf
 *	1/26/00
 */

void ls450_get_B(int dev_ID, double* B)
{
	/* Declare variables */
	int dev_open;
	int err;
	int num_scan;
	double field_reading;
	double multiplier;

    /* Check input parameters */
    if (dev_ID < 1 || dev_ID > LS450_MAX_NUM_DEV)
    {
    	Fmt(msg, "%s<dev_ID = %i, out of range", dev_ID);
    	ls450_error(msg);
    	return;
    }
    
    /* Exit here if testing without hardware */
    #ifdef DUMMY_DEVICES
    	return;
    #endif
    
    /* Check to make sure the device is open */
    dev_open = ls450_check_dev_open(dev_ID);
    if (dev_open != 1)
    {
    	ls450_error("LS450 not open");
    	return;
    }
    
    /* Make sure the teslameter is ready to send data */
    try_again:
	ls450_wait_until_data_ready(dev_ID);

    /* Get the field reading */
    ls450_out(dev_ID, "FIELD?");
    ls450_in(dev_ID, msg);
    num_scan = Scan(msg, "%s>%f", &field_reading);
    if (num_scan != 1)
    {
    	printf("LS450 problem getting field reading: %s\n", msg);
    	printf("Try again...\n");
    	Delay(1.);
    	goto try_again;
    }

    /* Get the multiplier */
    ls450_out(dev_ID, "FIELDM?");
    ls450_in(dev_ID, msg);
    if      (msg[0] == 'u') multiplier = 1.e-6;
    else if (msg[0] == 'm') multiplier = 1.e-3;
    else if (msg[0] == 'k') multiplier = 1.e3;
    else if (strlen(msg) == 0) multiplier = 1.;
    else
    {
    	printf("LS450 problem getting the multiplier: %s\n", msg);
    	printf("Try again...\n");
    	Delay(1.);
    	goto try_again;
    }

    /* Check the units */
    ls450_out(dev_ID, "UNIT?");
    ls450_in(dev_ID, msg);
    if (msg[0] != 'T')
    {
    	printf("LS450 problem getting the units: %s\n", msg);
    	printf("Try again...\n");
    	Delay(1.);
    	goto try_again;
    }
    
    /* Check for errors */
    err = ls450_get_errors(dev_ID);
    if (err != 0)
    {
        ls450_error("The teslameter has an error");
        ls450_close_dev(dev_ID);
        *B = 0.;
        return;
    }
    
    /* Return the field strength */
    *B = field_reading * multiplier;
    
    /* Done */
    return;
}

/*	**************************************************************  */
/*
 *	ls450_exit
 *  This function configures the LS450 for program exit and
 *	closes the device.
 *
 *	Input:
 *	dev_ID, device identifier
 *
 *	Zachary Wolf
 *	1/24/00
 */

void ls450_exit(int dev_ID)
{
	/* Declare variables */
	int dev_open;
	int err;

    /* Check input parameters */
    if (dev_ID < 1 || dev_ID > LS450_MAX_NUM_DEV)
    {
    	Fmt(msg, "%s<dev_ID = %i, out of range", dev_ID);
    	ls450_error(msg);
    	return;
    }
    
    /* Exit here if testing without hardware */
    #ifdef DUMMY_DEVICES
    	return;
    #endif
    
    /* Check to make sure the device is open */
    dev_open = ls450_check_dev_open(dev_ID);
    if (dev_open != 1)
    {
    	return;		 /* OK, already closed */
    }

	/* Close the device */
    ls450_close_dev(dev_ID);
    
    /* Done */
    return;
}

/*	**************************************************************  */

/*	PRIVATE FUNCTIONS  */

/*	**************************************************************  */
/*
 *	ls450_open_dev
 *	This function opens the device and returns an identifier for
 *	future references to the device.
 *
 *	Input:
 *	gpib_board_addr, address of the GPIB board the device is connected to
 *	gpib_dev_addr, GPIB address of the device (1 to 30, 0 is reserved)
 *
 *	Output:
 *	dev_ID, device identifier for future references to the device (-1 if there is a problem)
 *
 *	Zachary Wolf
 *	12/20/99
 */

int ls450_open_dev(int gpib_board_addr, int gpib_dev_addr)
{
	/* Declare variables */
    int i;
    int dev_ID;
    int descr;
    int err;

    /* Check input parameters */
    if (gpib_board_addr < 0 || gpib_board_addr > 10)
    {
    	Fmt(msg, "%s<gpib_board_addr = %i, out of range", gpib_board_addr);
    	ls450_error(cmd);
    	return -1;
    }
    if (gpib_dev_addr < 1 || gpib_dev_addr > 30)
    {
    	Fmt(msg, "%s<gpib_dev_addr = %i, out of range", gpib_dev_addr);
    	ls450_error(msg);
    	return -1;
    }

	/* Initialization */
    dev_ID = 0;

    /* Check to see if the device is already in the device table */
    for (i = 1; i <= LS450_MAX_NUM_DEV; i++)
    {
        if (dev_addr[i] == gpib_dev_addr)
        {
            dev_ID = i;
            return dev_ID;
        }
    }
    
    /* Find an ID for the device */
	for (i = 1; i <= LS450_MAX_NUM_DEV; i++)
	{
		if (dev_addr[i] == 0)
		{
			dev_ID = i;
			break;
		}
	}
     
    /* If an entry could not be opened in the device table, return an error */
    if (dev_ID <= 0)
    {
    	ls450_error("The device could not be opened");
        return  -1;
    }
    
    /* Open the device */
    /* Terminate write with LF EOI, add LF in send routine */
    /* Terminate read on LF, remove LF in read routine */
	descr = ibdev(gpib_board_addr, gpib_dev_addr, 0, T30s, 1, 0x1C0A);
	if (descr <= 0)
	{
		ls450_error("The device could not be opened");
		return  -1;
	}
    
    /* Open successful, save results */
    dev_addr[dev_ID] = gpib_dev_addr;
    dev_descr[dev_ID] = descr;
    dev_count++;
    
    /* Clear the device */
    err = ibclr(dev_descr[dev_ID]);
    if (err & 0x8000)
    {
    	ls450_error("Problem clearing device");
    }
    
    /* Return the device ID */
    return dev_ID;
}

/*	**************************************************************  */
/*
 *	ls450_close_dev
 *  This function closes the device.
 *
 *	Input:
 *	dev_ID, device identifier
 *
 *	Zachary Wolf
 *	12/20/99
 */

void ls450_close_dev(int dev_ID)
{
	/* Close the device */
    if (dev_descr[dev_ID] != 0)
    {
        ibonl(dev_descr[dev_ID], 0);
        dev_descr[dev_ID] = 0;
        dev_addr[dev_ID] = 0;
        dev_count--;
    }
    
    /* Done */
    return;
}

/*	**************************************************************  */
/*
 *	ls450_check_dev_open
 *  This function checks to see if the specified device is open.
 *	If the device has been opened, a 1 is returned, 0 otherwise.
 *
 *	Input:
 *	dev_ID, device identifier
 *
 *	Output:
 *	status, 1 if device is open, 0 otherwise
 *
 *	Zachary Wolf
 *	12/20/99
 */

int ls450_check_dev_open(int dev_ID)
{
	/* See if the device descriptor has a positive value */
    if (dev_descr[dev_ID] > 0)
    {
        return  1;		/* Open */
    }
    else
    {
	    return 0;		/* Not open */
	}
}

/*	**************************************************************  */
/*
 *	ls450_out
 *  This function writes a buffer of data to the device.
 *
 *	Input:
 *	dev_ID, device identifier
 *	buf, null terminated string, the contents up to \0 are sent
 *
 *	Output:
 *	err, 0 if ok, -1 otherwise
 *
 *	Zachary Wolf
 *	1/26/00
 */

int ls450_out(int dev_ID, char* buf)
{
	/* Declare variables */
	int nbytes;
	int err;
	char out_buf[LS450_MAX_CMD + 1];
	
	/* Add LF to the message */
	/* Add the wait-to-continue command */
	Fmt(out_buf, "%s<%s;*WAI%c", buf, 10);
	
	/* Send the message */
	nbytes = StringLength(out_buf);
	err = ibwrt(dev_descr[dev_ID], out_buf, (long)nbytes);
	
	/* Check for errors */
	if (err & 0x8000)
	{
		Fmt(msg, "%s<ibsta = %x, problem sending GPIB command", err);
		ls450_error(msg);
		return -1;
	}
	
	/* Done */
    return 0;
}

/*	**************************************************************  */
/*
 *	ls450_in
 *  This function reads a buffer of data from the device.
 *
 *	Input:
 *	dev_ID, device identifier
 *
 *	Output:
 *	buf, null terminated string, the contents from the device
 *	err, 0 if ok, -1 otherwise
 *
 *	Zachary Wolf
 *	1/26/00
 */

int ls450_in(int dev_ID, char* buf)
{
	/* Declare variables */
	int err;
	char in_buf[LS450_MAX_CMD];
	
	/* Read the message */
	err = ibrd(dev_descr[dev_ID], in_buf, LS450_MAX_CMD);
	
	/* Check for errors */
	if (err & 0x8000)
	{
		Fmt(msg, "%s<ibsta = %x, problem receiving GPIB input", err);
		ls450_error(msg);
		return -1;
	}
	
	/* Remove the LF terminator */
	Scan(in_buf, "%s[t10]>%s[t-]", buf);
	
	/* Done */
    return 0;
}

/*	**************************************************************  */
/*
 *	ls450_spoll
 *  This function performs a serial poll on the device.
 *
 *	Input:
 *	dev_ID, device identifier
 *
 *	Output:
 *	spoll, integer encoding the serial poll information
 *	err, 0 if ok, -1 otherwise
 *
 *	Zachary Wolf
 *	1/26/00
 */

int ls450_spoll(int dev_ID, int* spoll)
{
	/* Declare variables */
	int err;
	char spoll_byte;
	
	/* Perform the serial poll */
	err = ibrsp(dev_descr[dev_ID], &spoll_byte);
	
	/* Check for errors */
	if (err & 0x8000)
	{
		Fmt(msg, "%s<ibsta = %x, problem performing serial poll", err);
		ls450_error(msg);
		return -1;
	}
	
	/* Put the serial poll information into an integer */
	*spoll = (int) spoll_byte;
	
	/* Done */
    return 0;
}

/*	**************************************************************  */
/*
 *	ls450_wait_until_not_busy
 *  This function performs serial polls on the device until it determines
 *	that the device is ready to receive a command.
 *
 *	Input:
 *	dev_ID, device identifier
 *
 *	Zachary Wolf
 *	1/26/00
 */

void ls450_wait_until_not_busy(int dev_ID)
{
	/* Declare variables */
	int err;
	int status = 0;
	int num_scan;
	int counter = 0;
	enum {TRUE, FALSE} busy;
	
	/* Loop until the device is ready */
	busy = TRUE;
	while (busy == TRUE)
	{

		/* Read the standard event status register */
		ls450_out(dev_ID, "*ESR?");
		ls450_in(dev_ID, msg);
		num_scan = Scan(msg, "%s>%i", &status);
	    if (num_scan != 1)
	    {
	        ls450_message("The LS450 teslameter has an error in ls450_wait_until_not_busy.");
	        ls450_message(msg);
	        return;
	    }
		
		/* The teslameter is not busy if status bit 0 is set */
		if (status & 1) busy = FALSE;
		else busy = TRUE;
    
	    /* Check for errors */
	    if (status & 1);			/* OK, operation complete */
	    if (status & 2);			/* OK, not used */
	    if (status & 4) ls450_error("LS450: query error");
	    if (status & 8) ls450_error("LS450: DDE error");
	    if (status & 16) ls450_error("LS450: execution error");
	    if (status & 32) ls450_error("LS450: command error");
	    if (status & 64);			/* OK, not used */
	    if (status & 128);			/* OK, power on */
 		
		/* Allow time for the device to get ready */
		Delay(.2);
		
		/* No endless loops */
		counter++;
		//printf("%i\n", counter);
		if (counter > 100) busy = FALSE;
	
	/* End loop until device is ready */
	}
	
	/* Done */
    return;
}

/*	**************************************************************  */
/*
 *	ls450_wait_until_data_ready
 *  This function performs checks the device until it determines
 *	that the device is ready to send its data.
 *
 *	Input:
 *	dev_ID, device identifier
 *
 *	Zachary Wolf
 *	1/26/00
 */

void ls450_wait_until_data_ready(int dev_ID)
{
	/* Declare variables */
	int err;
	int status = 0;
	int num_scan;
	int counter = 0;
	enum {TRUE, FALSE} ready;
	
	/* Loop until the device has its data ready */
	ready = FALSE;
	while (ready == FALSE)
	{

		/* Read the status byte register */
		ls450_out(dev_ID, "*STB?");
		ls450_in(dev_ID, msg);
		num_scan = Scan(msg, "%s>%i", &status);
	    if (num_scan != 1)
	    {
	        ls450_message("The LS450 teslameter has an error in ls450_wait_until_data_ready.");
	        ls450_message(msg);
	        return;
	    }
		
		/* The data is ready if status bit 0 is set */
		if (status & 1) ready = TRUE;
		else ready = FALSE;
		
		/* Allow time for the device to get ready */
		Delay(.2);
		
		/* No endless loops */
		counter++;
		//printf("%i\n", counter);
		if (counter > 100) ready = TRUE;
	
	/* End loop until device is ready */
	}
	
	/* Done */
    return;
}

/*	**************************************************************  */
/*
 *	ls450_get_errors
 *  This function obtains device errors.
 *	The operator is alerted if there is an error.
 *
 *	Input:
 *	dev_ID, device identifier
 *
 *	Output:
 *	err, 0 if no errors, -1 otherwise
 *
 *	Zachary Wolf
 *	12/20/99
 */

int ls450_get_errors(int dev_ID)
{
	/* Declare variables */
    int status;
    int spoll;
    int num_scan;

	/* Read the standard event status register and clear it */
	ls450_out(dev_ID, "*ESR?");
	ls450_in(dev_ID, msg);
	num_scan = Scan(msg, "%s>%i", &status);
    if (num_scan != 1)
    {
        ls450_message("The LS450 teslameter has an error.");
        ls450_message(msg);
        return -1;
    }
    
    /* Debug */
    //printf("ESR = %i\n", status);
    
    /* Check for errors */
    if (status & 1);			/* OK, operation complete */
    if (status & 2);			/* OK, not used */
    if (status & 4) ls450_error("LS450: query error");
    if (status & 8) ls450_error("LS450: DDE error");
    if (status & 16) ls450_error("LS450: execution error");
    if (status & 32) ls450_error("LS450: command error");
    if (status & 64);			/* OK, not used */
    if (status & 128);			/* OK, power on */
    
    /* Perform a serial poll to read the status byte register and clear it */
	ls450_spoll(dev_ID, &spoll);
	
	/* Debug */
    //printf("SBR = %i\n", spoll);
    
    /* Check for errors */
    /* No new errors, overload is handled in get_B function */
    //if (spoll & 16) ls450_error("LS450: overload");
    
    /* Done */
    return 0;
}

/*	**************************************************************  */
/*
 *	ls450_message
 *  This function handles messages about the LS450.
 *
 *	Input:
 *	message, string to display in standard I/O
 *
 *	Zachary Wolf
 *	12/20/99
 */

void ls450_message(char* message)
{
	/* Print the message */
	printf("%s\n", message);
	
	/* Done */
	return;
}

/*	**************************************************************  */
/*
 *	ls450_error
 *  This function handles error messages for the LS450.
 *
 *	Input:
 *	message, string to display in standard I/O
 *
 *	Zachary Wolf
 *	12/20/99
 */

void ls450_error(char* message)
{
	/* Declare variables */
	char buf[80];
	
	/* Notify the operator of the error */
	printf("\nLS450 ERROR: %s\n", message);
	Beep();
	Delay(.5);
	Beep();
	
	/* Terminate the program if the operator desires */
	printf("Press ENTER to continue.\nPress any key then ENTER to terminate program.\n");
	fgets(buf, 80, stdin);
	if (buf[0] == '\n') return;
	else exit(0);
}