Hi all,
I have two files,as follows...when I simulate the sub routine is never executed.

file 1(main.asm)

#include "rs_485.asm"

org 0000h
ljmp on_reset


org 002bh
on_reset:
mov ie,#00h
mov sp,#07h
lcall rs_485_init ;initailise the serial communication

end


file 2(rs_485.asm)

rs_485_init:

mov tmod,#20h ;timer 1 in mode2(auto reload)
mov th1,#-3 ;reload value for 9600 baud rate
mov scon,#50h ;8 bit,1 start,1 stop and REN enabled
clr ti ;clear transmit interrupt flag
clr ri ;clear receive interrupt flag
setb tr1 ;Start timer 1
ret