CCS/MSP432P401R: RS422 protocol and eUSCI_A UART

Part Number: MSP432P401R

Tool/software: Code Composer Studio

Hi

I have a device (encoder to measure the rotation velocity of motor shaft), in my application that works with RS422 protocol serial communication and TTL logic. I just need to receive data from the encoder and no transmission from MCU to the encoder is required. I have used EUSCIA3 to account for asynchronous communication. But it is not working. Can you please let me know if I am on the right direction and help me resolve the issue? and also what specifications (baud rate, etc.) are good for the EUSCIA3 given that my signal frequency is variable between 0 and 160kHZ. A snippet of the code is provided below for your review. 

Thanks in advance!

#include "msp.h"

int flag=0;// To check if the reception in ISR is done.
unsigned short RX;//the received data is stored in RX.
long long int i;// Is used in for loop to wait for a while.

void main(void)
{
	WDT_A->CTL = WDT_A_CTL_PW | WDT_A_CTL_HOLD;		// stop watchdog timer
//******Pin configurations**********//
	  // Configure UART pins
	    P9->SEL0 |= BIT6;                // set 1-UART pin as secondary function
	    P1DIR |=BIT0;
	    // Configure UART
	    EUSCI_A3->CTLW0 |= EUSCI_A_CTLW0_SWRST; // Put eUSCI in reset
	    EUSCI_A3->CTLW0 = EUSCI_A_CTLW0_SWRST | // Remain eUSCI in reset
	            EUSCI_B_CTLW0_SSEL__SMCLK;      // Configure eUSCI clock source for SMCLK
	    // Baud Rate calculation
	    // 12000000/(16*9600) = 78.125
	    // Fractional portion = 0.125
	    // User's Guide Table 21-4: UCBRSx = 0x10
	    // UCBRFx = int ( (78.125-78)*16) = 2
	    EUSCI_A3->BRW = 78;                     // 12000000/16/9600
	    EUSCI_A3->MCTLW = (2 << EUSCI_A_MCTLW_BRF_OFS) |
	            EUSCI_A_MCTLW_OS16;

	    EUSCI_A3->CTLW0 &= ~EUSCI_A_CTLW0_SWRST; // Initialize eUSCI

	    EUSCI_A3->IFG &= ~EUSCI_A_IFG_RXIFG;    // Clear eUSCI RX interrupt flag


	    // Enable global interrupt
	    __enable_irq();

	    // Enable eUSCIA0 interrupt in NVIC module
	    NVIC->ISER[0] = 1 << ((EUSCIA3_IRQn) & 31);
while (1)
{
    EUSCI_A3->IE |= EUSCI_A_IE_RXIE;// Enable USCI_A0 RX interrupt
    while(flag==0);// wait until the flag in the ISR become 1.
    EUSCI_A1->IE &= ~EUSCI_A_IE_RXIE;// Enable USCI_A0 RX interrupt
    flag=0;//Reset the flag.
    printf("RX: %d",RX);//print the RX
    printf("\n");//Go to the next line.
    for (i=100000;i>1;i--);//wait for a while.
}

	}

	// UART interrupt service routine
	void EUSCIA3_IRQHandler(void)
	{
	    if (EUSCI_A3->IFG & EUSCI_A_IFG_RXIFG)
	    {
	        // Check if the TX buffer is empty first
	        while(!(EUSCI_A3->IFG & EUSCI_A_IFG_TXIFG));

	        // Echo the received character back
	        RX = EUSCI_A3->RXBUF;
	        P1OUT ^=BIT0;
	    }
	    flag=1;
	   // EUSCI_A1->IFG &= ~EUSCI_A_IFG_RXIFG;

	}