can i detect error for one wire error data

[a]

because i send data from board1 to board2 is data='0xa1' and board2 receive data='0xa0' and sometime receive 0xa1 and how can i check error.
And one question if data from board1 is send. if data is error. board1 or board2 is detect error. i think is board 2 is detected and send error to board1 . Is it right.

below is my source code of board1
===============================================================================
#include <16F877.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=4000000)

#use rs232(baud=9600, float_high, ERRORS, parity=E,xmit=PIN_B0,rcv=PIN_B0,bits=8)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#bit ninth_bit = RS232_ERRORS.7
#bit collision = RS232_ERRORS.6
#bit intf = 11.1

void show_print(char xxdata);
void out_led(char char1);

#define RS PIN_C0
#define RW PIN_C1
#define EN PIN_C2

#define SE1 PIN_A1
#define SE2 PIN_A2
#define CARD_IN !input(PIN_B1)

.....
......
........ other part of program
........

#int_ext
void pbus_isr()
{
BYTE data;
Set_tris_b(0b00000001);

if(kbhit())
{
data=getc();

if(ninth_bit)
{
if(data==0xf2)
{
delay_cycles(1);
}
}
else
{
show_print(data);
wcharxy(2,1,data);
}
}
}

void pbus_write_ram(byte cha)
{
BYTE checksum,i;

retry:
disable_interrupts(GLOBAL);
collision=false;

ninth_bit=0;
putc(cha); if(collision) { goto error; } //0000 1101
out_led(2);

intf=false;
enable_interrupts(GLOBAL);
return;

error:
delay_ms(16);
enable_interrupts(GLOBAL);
goto retry;
}

#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7,bits=8) // Jumpers: 8 to 11, 7 to 12

void show_print(char xxdata)
{
putc(xxdata);
}

#include <input.c>

void main()
{

BYTE to,i,value,cou,sendch;

int CIN;

printf("\r\nPress S to send.\r\n");

port_b_pullups(TRUE);
ext_int_edge( h_to_l );

Set_tris_a(0b000000);
Set_tris_b(0b00000001);

init_lcd();

while(1)
{
if(CARD_IN)
{
delay_ms(250);
IF(CIN==0)
{
OUTPUT_LOW(PIN_A5);
DELAY_MS(10);
OUTPUT_HIGH(PIN_A5);
CIN=1;
}
sendch='ก';
pbus_write_ram(sendch);
hex_to_lcd(1,1,sendch);
delay_ms(500);
pbus_write_ram('ข');
hex_to_lcd(1,1,'ข');
delay_ms(500);
pbus_write_ram('ฃ');
hex_to_lcd(1,1,'ฃ');
delay_ms(500);
pbus_write_ram('ฮ');
hex_to_lcd(1,1,'ฮ');
delay_ms(500);

output_high(PIN_A3);
enable_interrupts(global);
enable_interrupts(int_ext);
}
else
{
disable_interrupts(global);
disable_interrupts(int_ext);
out_led(0x02);
output_low(PIN_A3);
CIN=0;
}
}
}


below is my source code of board2
====================================
#include <16F876.h>
#fuses HS,NOWDT,NOPROTECT,NOLVP
#use delay(clock=3579545)

#use rs232(baud=9600, float_high, ERRORS ,parity=E,xmit=PIN_B7,rcv=PIN_B7,bits=8)

#bit ninth_bit = RS232_ERRORS.7
#bit collision = RS232_ERRORS.6
#bit intf = 11.1

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define RW PIN_A0
#define RS PIN_A1
#define EN PIN_A2

#define LED0 PIN_A3
#define LED1 PIN_A4
byte cou;

.......
........
........ other part of program
......
.........

void pbus_write_ram(byte cha)
{
BYTE checksum,i;

retry:
disable_interrupts(GLOBAL);
collision=false;

ninth_bit=1;
out_led(1);
ninth_bit=0;
putc(cha); if(collision) { out_led(3); goto error; } //0000 1101
out_led(2);

intf=false;
enable_interrupts(GLOBAL);
return;

error:
delay_ms(16);
wcharxy(2,5,'E');
enable_interrupts(GLOBAL);
goto retry;
}

#int_RB
void checkserial(void)
{
byte data;

if(kbhit())
{
data=getc(); if(collision) { output_low(PIN_B7); wcharxy(2,3,'E'); }

if(ninth_bit)
{
if(data==0xf2)
{
delay_cycles(1);
}
}
else
{
hex_to_lcd(1,1,data);
}
}
}

#include <input.c>

void main() {
BYTE to,i,value;

port_b_pullups(TRUE);

init_lcd();

ext_int_edge( h_to_l );
enable_interrupts(global);
enable_interrupts(int_ext);
enable_interrupts(int_rb);
enable_interrupts(int_buscol);

while (TRUE)
{
delay_us(1);
}
}

=============

can i detect my error on one wire. please help me.

[a]

now i'm test it again.
send 0x15 from board 1 and show lcd on board1 it is show 15 by my function hex_to_lcd but in board is receive and show data on lcd too. it is receive 0x14 or sometime 0x12 but more time receive 0x15 but in my sourcecode if parity bit is not true it should show E in lcd but it's not