Accessing the Serial Port in Linux in C - c

Question

I am trying to write and read data through serial port to a USB device in linux.I am able to write the data but I am not read the complete data that the USB device is sending to me.The underlying code is mine.Please do point out any mistake if so.
#include<stdio.h>
#include<stdlib.h>
#include<errno.h>
#include<fcntl.h>
#include<termios.h>
#include<unistd.h>
#define SERIAL_PORT_PATH "/dev/ttyACM0"
struct termios SerialPortSettings;
unsigned char Buffer[256] = {0X01,0X04,0X00,0X4B,0x01,0XB1};
int Serial_Port_Descriptor = 0;
int Open_flag = O_RDWR | O_NOCTTY | O_NDELAY;
int Set_Nonblock_Open_flag();
int Serial_Port_Configuring();
int Read_Serial_Port();
int main()
{
Serial_Port_Descriptor = open(SERIAL_PORT_PATH,Open_flag);
if(Serial_Port_Descriptor > 0)
{
printf("Serial_Port has been Opened \n");
Set_Nonblock_Open_flag();
}
else
{
perror("Error:");
}
Serial_Port_Configuring();
write(Serial_Port_Descriptor,&Buffer,sizeof(Buffer));
sleep(2);
while(1)
{
Read_Serial_Port();
}
close(Serial_Port_Descriptor);
return 0;
}
int Set_Nonblock_Open_flag()
{
Open_flag = fcntl(Serial_Port_Descriptor,F_GETFL,Open_flag);
if(Open_flag == -1)
{
return -1;
}
else if (0)
{
Open_flag |= O_NONBLOCK;
printf("The Flag is set to Nonblock \n");
}
else
{
Open_flag &= ~O_NONBLOCK;
}
return fcntl(Serial_Port_Descriptor,F_SETFL,Open_flag);
}
int Serial_Port_Configuring()
{
tcgetattr(Serial_Port_Descriptor,&SerialPortSettings);
cfsetispeed(&SerialPortSettings,B115200);
cfsetospeed(&SerialPortSettings,B115200);
SerialPortSettings.c_cflag &= ~PARENB;
SerialPortSettings.c_cflag &= ~CSTOPB;
SerialPortSettings.c_cflag &= ~CSIZE;
SerialPortSettings.c_cflag |= CS8;
SerialPortSettings.c_cflag &= ~CRTSCTS;
SerialPortSettings.c_cflag |= CREAD | CLOCAL;
SerialPortSettings.c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP | INLCR | IGNCR | ICRNL | IXON | IXOFF | IXANY);
SerialPortSettings.c_lflag &= ~(ICANON | ECHO | ECHONL | ISIG | IEXTEN);
SerialPortSettings.c_oflag &= ~OPOST; /* No Ouptut Processing */
SerialPortSettings.c_cc[VMIN] = 1; /* Read atleast 1 character */
SerialPortSettings.c_cc[VTIME] = 0; /* Wait Indefinitely */
tcflush(Serial_Port_Descriptor,TCIOFLUSH);
if(tcsetattr(Serial_Port_Descriptor,TCSANOW,&SerialPortSettings) != 0)
{
printf("Error: The Settings are not been Configured \n");
return -1;
}
else
{
printf("Settings have been Configured \n");
}
return 0;
}
int Read_Serial_Port()
{
int Serial_Port_Read = read(Serial_Port_Descriptor,&Buffer,sizeof(Buffer));
if(Serial_Port_Read < 0)
{
fputs("Read of bytes() has failed \n",stderr);
return -1;
}
else if(Serial_Port_Read > 0)
{
printf("%d bytes has been read \n",Serial_Port_Read);
for(int i=0;i <= Serial_Port_Read;i++)
{
printf("%02X",(unsigned char)Buffer[i]);
}
}
return 0;
}