Dear Mahesh,
Thank you very much for your help.I've decided to check if my rfid is transmitting something to the 89s so i tried this little code

AJMP START

START:  MOV TMOD,#20h
        MOV SCON,#50h
        MOV TH1,#0F4h          ;UART is configured for desired BAUD
        MOV TL1,#0F4h
        
        SETB TR1                       ;Run T1 for BAUDRATE GeneratioN
         SETB P2.0                ;the LED must be in off state

WAIT_RX: JNB RI,WAIT_RX
         MOV A,SBUF
         CLR RI
         CJNE A,#0Ah,WAIT_RX
         SETB 00h
         SJMP CHECK

CHECK: JNB 00h,WAIT_RX
        CLR P2.0
        
END
 

...............and it worked.It is a real breakthrough for me to finally see something working and it gave me a morale boost.very grateful for your help