Serial Communication read() Error - c

Question

This should be fairly straightforward for someone in the know, but I have been struggling for a bit and would appreciate some thoughts. I am writing an application that reads from a serial comm port.
My Setup:
I have a windows machine with putty open and connected to my comm port of interest.
I have a linux (ubuntu) machine in which I am writing this software (in C).
I am typing into putty on the windows machine and trying to read it with my application on the linux machine.
What I have:
So far, using the code below I can successfully write to the putty display on the windows machine from my application on the linux computer, but I cannot read the buffer on my linux machine when I type on the windows machine.
Code:
#include <stdio.h> // standard input / output functions
#include <stdlib.h>
#include <string.h> // string function definitions
#include <unistd.h> // UNIX standard function definitions
#include <fcntl.h> // File control definitions
#include <errno.h> // Error number definitions
#include <termios.h>
int openport()
{
int USB = open( "/dev/ttyUSB0", O_RDWR| O_NOCTTY | O_NONBLOCK );
struct termios tty;
struct termios tty_old;
memset(&tty, 0, sizeof tty);
/* Error Handling */
if ( tcgetattr( USB, &tty ) != 0 )
{
printf("Error 1, or something");
}
/* Save old tty parameters */
tty_old = tty;
/* Set Baud Rate */
cfsetospeed (&tty, (speed_t)B9600);
cfsetispeed (&tty, (speed_t)B9600);
/* Setting other Port Stuff */
tty.c_cflag &= ~PARENB; // Make 8n1
tty.c_cflag &= ~CSTOPB;
tty.c_cflag &= ~CSIZE;
tty.c_cflag |= CS8;
tty.c_cflag &= ~CRTSCTS; // no flow control
tty.c_cc[VMIN] = 1; // read doesn't block
tty.c_cc[VTIME] = 5; // 0.5 seconds read timeout
tty.c_cflag |= CREAD | CLOCAL; // turn on READ & ignore ctrl lines
/* Make raw */
cfmakeraw(&tty);
/* Flush Port, then applies attributes */
tcflush( USB, TCIFLUSH );
if ( tcsetattr ( USB, TCSANOW, &tty ) != 0)
{
printf("Error, or something");
}
return USB;
}
int main()
{
int n = 0;
int j = 0;
unsigned char buf[10] = {0,0,0,0,0,0,0,0,0,0};
printf("Hello world!\n");
int USB = openport();
unsigned char cmd[] = "INIT Hey SHanahas \r";
int n_written = 0;
do
{
n_written += write( USB, &cmd[n_written], 1 );
}
while (cmd[n_written-1] != '\r' && n_written > 0);
printf("Here\n\n");
do
{
n = read( USB, &buf, 1 );
printf("%s \n",buf);
printf("%d",n);
}
while( buf != '\r' && n > 0);
printf("Herr2");
return 0;
}
Does anyone have any thoughts on what might be happening? the read() command returns a -1 error.
Thanks!