you may use these values. The instructions are in assembly language. translate them to C51 accordingly.
MOV SCON, #50H ;INITIALIZATION
MOV TMOD, #20H ;Initialize Timer
MOV TH1,#-13 ;load Timer for 2400 baud rate using 12MHz Crystal
SETB TR1 ;start Timer
CLR TI ;Clear interrupts
CLR RI
MOV IE, #90H ;Enable Serial Port Interrupt
SETB PS ;Give High Priority to serial port interrupt