Half Duplex RS485 linux Serial USB Programing in C

I’m trying to setup half duplex communication in Ubuntu 14.04 in my program. I have my RS485 transceiver using the RTS line to toggle back and forth between transmit and receive. I’m using a speak when spoken to system and this program is the master. The problem is that the RTS isn’t toggling back off when I’m done sending the package so I can receive the data. Basically I want it to turn the RTS high, send the data, turn the RTS low, then read the data. Any help would be great. I"m using a USB to serial adapter with a Serial to RS485 transceiver for the master. My TX from the master is great! but the RTS isn’t going low to switch the RS485 transceiver into receive mode. The slaves all are Arduino’s with RS485 transceivers attached. I’ve been lookking at the signals with a scope and a logic analyzer and the RTS never goes low once the master send it’s first packet.

Here is my linux Code:

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <errno.h>
#include <termios.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/signal.h>
#include <sys/types.h>

#define BAUDRATE B38400
#define COMPORT "/dev/ttyUSB0"
#define _POSIX_SOURCE 1
#define FALSE 0
#define TRUE 1

#define STX_KEYPAD 0xE1

#define CRC_HI 0xD8
#define CRC_LOW 0xC3

volatile int STOP=FALSE;

int ser_port;
int bus_address = 1;
int message_length = 0;
struct termios oldtio,newtio;
unsigned char rxbuf[256];
unsigned char tx_flags = 0;

void openCommPort();
void sendSerial();
int setRTS(int level);

int main(void)
 printf("Sending Serial Data\r\n");
 printf("All Done\r\n");

     return EXIT_SUCCESS;

void openCommPort()
   ser_port = open(COMPORT, O_RDWR | O_NOCTTY | O_NONBLOCK);
   if (ser_port == -1)
       perror("Unable to open port");

   if(tcgetattr(ser_port,&oldtio) <0)// save current port settings
       perror("Couldn't get old terminal attributes");
       exit (-1);

    bzero(&newtio, sizeof(newtio));

    newtio.c_cflag = BAUDRATE | CS8 | CLOCAL | CREAD | CRTSCTS;     

     newtio.c_iflag = IGNPAR | ICANON;

    newtio.c_oflag = 0;

       // set input mode (non-C, no echo,...)
   newtio.c_lflag = 0;

   newtio.c_cc[VTIME]    = 0;   // inter-character timer unused
   newtio.c_cc[VMIN]     = 0;   // blocking read until 5 chars received

   tcflush(ser_port, TCIFLUSH);

void sendSerial()
unsigned char tx_header[6];

tx_header[0] = STX_KEYPAD;
tx_header[1] = bus_address;
tx_header[2] = tx_flags;
tx_header[3] = message_length;
tx_header[4] = CRC_HI;
tx_header[5] = CRC_LOW;

if((write(ser_port, tx_header, 6)) != 6)
     printf("Error sending data!  Not all bytes sent\r\n");


int setRTS(int level)
int status;

 if (ioctl(ser_port, TIOCMGET, &status) == -1)
        perror("getRTS(): TIOCMSET");
        return 0;

     status |= TIOCM_RTS;
    status &= ~TIOCM_RTS;

if (ioctl(ser_port, TIOCMSET, &status) == -1)
    perror("setRTS(): TIOCMSET");
    return 0;

return 1;