Hi Jose,

try to use a terminal program (Hyperterminal) at first (8 bit, no handshake).

To verify, if on the 8051 the timer mode, timer reload value, uart mode, PCON are initialized right, you can use the following test routine.
It echoes back the received character + 1:

loop:
jnb ri, loop
clr ri
inc sbuf
sjmp loop

E.g. on sending 'A' it returns 'B'


Peter