#include <sys/types.h>
        #include <sys/stat.h>
        #include <fcntl.h>
        #include <termios.h>
        #include <stdio.h>
        #include <stdlib.h>
        #include <string.h>
        #include <unistd.h>
        #include <iostream>
        #include <stdlib.h>
        #include <sys/ioctl.h>
        #include <stdlib.h>
        
        /* baudrate settings are defined in <asm/termbits.h>, which is
        included by <termios.h> */
        #define BAUDRATE B9600            
      
        /* change this definition for the correct port */
        #define MODEMDEVICE "/dev/ttyS0"
        #define _POSIX_SOURCE 1 /* POSIX compliant source */

        #define FALSE 0
        #define TRUE 1

        volatile int STOP=FALSE;
        using namespace std;
        
        main()
        {          
            
          char test[255];
          int fd,c, res,testen;
          int sercmd, serstat;
          struct termios oldtio,newtio;
          unsigned char buf[255];          

        /*
          Open modem device for reading and writing and not as controlling tty
          because we don't want to get killed if linenoise sends CTRL-C.
        */
                  
         fd = open(MODEMDEVICE, O_RDWR );
         if (fd <0){
            cout<<"error \n";
         }

         tcgetattr(fd,&oldtio); /* save current serial port settings */
         bzero(&newtio, sizeof(newtio)); /* clear struct for new port settings */
        
        /*
          BAUDRATE: Set bps rate. You could also use cfsetispeed and cfsetospeed.
          CRTSCTS : output hardware flow control (only used if the cable has
                    all necessary lines. See sect. 7 of Serial-HOWTO)  
          CS8     : 8n1 (8bit,no parity,1 stopbit)
          CLOCAL  : local connection, no modem contol
          CREAD   : enable receiving characters
        */
         newtio.c_cflag = BAUDRATE | CS8 | CLOCAL |CREAD;
         /*
          IGNPAR  : ignore bytes with parity errors
          ICRNL   : map CR to NL (otherwise a CR input on the other computer
                    will not terminate input)
          otherwise make device raw (no other input processing)
        */
         newtio.c_iflag = IGNPAR | ICRNL | IGNBRK;
        
        /*
         Raw output.
        */
         newtio.c_oflag = 0;
         /*
          ICANON  : enable canonical input
          disable all echo functionality, and don't send signals to calling program
        */
         newtio.c_lflag = ICANON;
        /*
          initialize all control characters
          default values can be found in /usr/include/termios.h, and are given
          in the comments, but we don't need them here
        */

        newtio.c_cc[VEOF]     = 3;    
        newtio.c_cc[VMIN]     = 5;     /* blocking read until 5 character arrives */
        /*
          now clean the modem line and activate the settings for the port
        */
         tcflush(fd, TCIFLUSH);
         tcsetattr(fd,TCSANOW,&newtio);
         //RTS DISABLE !!!!         <--------- this is required to be able to communicate with my PowerMeter
          ioctl(fd, TIOCMGET, &serstat);          
          sercmd = TIOCM_RTS;
          ioctl(fd, TIOCMBIC, &sercmd); // Set the RTS pin.
          ioctl(fd, TIOCMGET, &serstat);
         while (STOP==FALSE) {  
         //Protocol is write " " to powermeter, then the powermeter will send its data back

             char spatie[2] = " ";
            if (write(fd,spatie,1) < 1)
            {                
                cout<<"-------------error--------------\n";
            }
             sleep(2);
            for (int j = 0; j <4; j++){              
                      
                res = read(fd,buf,15);            
                cout << "alle data \n";
            
                for(int i= 0; i <res; i++){
                cout <<" buf ["<< i << "] :"<< (long)buf[i]<<"\n";
            
                }            
            
                cout<<"\ngefilterde data \n";
            
                int sizebuf = sizeof buf;
                cout << " aantal data = " << res << "\n";
            
                cout << " data 1 : " <<  (int) buf[res-3] << "\n";
                cout << " data 2 : " << (int) buf[res-2]<< "\n";
                cout << " data 3 : " << (int) buf[res-1]<< "\n";
                        
            }
            getchar(); // Wait for the return key before continuing.
         }
         /* restore the old port settings */
         tcsetattr(fd,TCSANOW,&oldtio);
         cout<<"-----einde-----\n";
        }