ethan@meow:/var/www$ gcc -g -Wall -o DriverScale DriverScale.c scale9.c  
scale9.c: In function ‘scale9':
scale9.c:53:2: warning: implicit declaration of function ‘cfsetispeed' [-Wimplicit-function-declaration]
  cfsetispeed(&options, B9600);
  ^
scale9.c:54:2: warning: implicit declaration of function ‘cfsetospeed' [-Wimplicit-function-declaration]
  cfsetospeed(&options, B9600);
  ^
scale9.c:65:2: warning: implicit declaration of function ‘tcflush' [-Wimplicit-function-declaration]
  tcflush(fp1, TCOFLUSH);
  ^
scale9.c:76:2: warning: implicit declaration of function ‘tcgetattr' [-Wimplicit-function-declaration]
  tcgetattr(fp1, &options); //The tcgetattr function fills the termios structure 
  ^
scale9.c:84:2: warning: implicit declaration of function ‘tcsetattr' [-Wimplicit-function-declaration]
  tcsetattr(fp1, TCSANOW, &options); /* apply the settings */
  ^
scale9.c:125:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^

float scale9(void);

#include <stdio.h>

int main(void) 

{
    float wgt;
    
    printf ("%s", "weight from scale9\n");
    wgt = scale9();
    printf("%f", wgt);
    return 0;
}

/*
*Scale9  Write data to Serial Port and Read it
*
*/ 

#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <stropts.h>
#include <asm/termios.h>
#include <unistd.h>
#include <string.h>
//#include <termios.h>

#define MODEMDEVICE "/dev/ttyS0"
//void main(void)
float scale9(void) 
{
    char buf[8] = " ", buf2[8] = " ";
  
    FILE *fp1, *fp2; 
    float wgt;
    int i;

    struct termios options;

    fp1 = fopen(MODEMDEVICE, "w+");
    
    fp2 = fopen("/tmp/testfile.txt", "w+");

    if(fp2 == NULL)
    {
        printf("testfile error. \n");
    }

    
    if(fp1 == NULL)
    {
        printf("initiation error. \n");
    }

    printf("  hellow scale");


    cfsetispeed(&options, B9600);
    cfsetospeed(&options, B9600);




    options.c_cflag |= ~PARENB;  // Allow parity to be set

    options.c_cflag &= ~CSTOPB; // 1 stop bit 
    options.c_cflag &= ~CSIZE;  // Mask the character size bits 
    options.c_cflag |= CS7;     // 7 bits
    tcflush(fp1, TCOFLUSH);
    
    
    printf("  hellow scale2");

    
    tcgetattr(fp1, &options); //The tcgetattr function fills the termios structure 
    //you provide with the current serial port configuration. 
    //After we set the baud rates and enable local mode and serial data receipt, 
    //we select the new configuration using tcsetattr. The TCSANOW constant specifies 
    //that all changes should occur immediately without waiting for output data to finish 
    //sending or input data to finish receiving. There are other constants 
    //to wait for input and output to finish or to flush the input and output buffers.
    
    tcsetattr(fp1, TCSANOW, &options); /* apply the settings */
    
    
printf("scale7");
    fprintf(fp1, "%s","W\r\n");  //send the command to the scale
    fread(buf, 1, 7,fp1); strip the first character, which is a carriage return
    printf("buf\n");
printf("scale7#2");
    for (i= 1; i < 7; i++)
        buf2[i] = buf[i];
    printf("%s", buf2);
    
    for (i = 0; i<8; i++)
        printf("%c\n", buf[i]);
        
printf("\n%s#3", buf);
    
    printf("buf2\n");

    
    for (i = 0; i<7; i++)
        printf("%c\n", buf2[i]);
  printf("buf2\n");
printf("scale7#4");
    printf("%s", buf2);
    wgt = atof(buf2);
    printf("wgt\n");
     printf("%f", wgt);
    

printf("\n%s", buf2);
    fclose(fp1);
   fwrite(buf, 1, 7,fp2 );
   fwrite(buf2, 1, 7,fp2 );
    
    fclose(fp2);

}