Hello Harnan,
I cleaned up your code to make it more readable.
Regards,
Charles Bannister

;********************************************************************
;	Subject: uC to VBfront end
;	Full Name: Harnam Singh Thakur Registered Member User Profile 
;	http://www.8052.com/forum/read.phtml?id=79631
;	Date: 10-20-04 08:36
;	Read: 28 times
;	Score: Hasn't been scored  
;	Hello friends, 
;	I am struggling to send the data from uC (Port pins which are 
;	connected to switches) to VBfront end.Any kind of suggestions 
;	or help will be highly appreciated. 
;	Whereas sending data from the VB front is OK . 
;	I am using P89C51rd2 
;	The project have vb front end with 5 switches and status 
;	indicators and it is working ok, while sending #31H and #38h 
;	for switching on and off light1 and so on 
;	respectively.Status is being changed by receiving #43H_ _ _ _ #47H. 
;	The code is 
;	Regards 
;	Harnam 
;********************************************************************

ORG 0000H

reset1: 
	MOV IE,#00000000B 
	MOV TMOD,#00100000 
	MOV TL1,#0FDH 
	MOV TH1,#0FDH 
	MOV SCON,#01000000B 
	SETB TR1 
	MOV P1,#11111111B 

INDEX: 	ACALL SUB_RXD 
	ACALL_LIGHT1_ON 
	ACALL_LIGHT1_OFF 
	;--------------- 
	;--------------- 
	ACALL_LIGHT5_ON 
	ACALL_LIGHT5_OFF 
	SJMP INDEX 

SUB_RXD:
	JNB RI,$ 
	CLR RI 
	MOV A, SBUF 
	RET 
LIGHT1_ON: 
	CJNE A,#31h,NEXT 
	CLR P1.0 
	ACALL sUB_TXD1 
	SJMP INDEX 
LIGHT1_OFF: 
	cjne A,#38h,NEXT 
	SETB P1.0 
	SJMP INDEX 
NEXT: 	RET 
SUB_TXD1: 
	MOV SBUF, 43H 
	JNB TI,$ 
	CLR TI 
	RET 
	;--- 

	;----- 

SUB_TXD5: 
	MOV SBUF, 47H 
	JNB TI,$ 
	CLR TI 
	RET 
	END 

;********************************************************************
;	Now I like to connect 8 switches to uC Port 0 and send #30H 
;	to #37H to front end. I tried Mazidi book example 11-10, I 
;	can not understand how to send the #30H,#31H,#33H... to 
;	serial. In previous program by pressing 
;	switch 1 in front end, uC was receiving #31H and switching 
;	On light1. In the following program when I toggle P0.0, 
;	front end is receiving garbage How to send the data from 
;	individual pins ie. P0.0,P0.1......P0.7 to 
;	front end ???? 
;********************************************************************

ORG 0
reset2:	LJMP MAIN
 
ORG 000BH 			;ISR FOR TIMER 0 
	CPL P0.1 		;TOGGLE P0.1 
	RETI 			;RETURN FROM ISR 

ORG 23H 
	LJMP SERIAL 		;JUMP TO SERIAL INT. ISR 

ORG 30H 

MAIN: 	MOV P1,#0FFH 		;MAKE P1 AN INPUT PORT 
	MOV TMOD,#22H 		;TIMER 0&1,MODE 2, AUTO RELOAD 
	MOV TH1,#0F6H 		;4800 BAUD RATE 
	MOV SCON,#50H 		;8-BIT,1 STOP,REN ENABLED 
	MOV TH0,#-92 		;FOR 5 KHZ WAVE. 
	MOV IE,#10010010B 	;ENABLE SERIAL,TIMER 0 INT. 
	SETB TR1 		;START TIMER 1 
	SETB TR0 		;START TIMER 0 
BACK: 	MOV A,P1 		;READ DATA FROM PORT 1 
	MOV SBUF,A 		;GIVE A COPY TO SBUF 
	MOV P2,A 		;WRITE IT TO P2 
	SJMP BACK 		;STAY IN LOOP INDEFINITELY 
				;------------------SERIAL PORT ISR 
ORG 100H 

SERIAL: JB TI,TRANS 		;JUMP IF TI IS HIGH 
	MOV A,SBUF 		;OTHERWISE DUE TO RECEIVE 
	MOV P0,A 		;SEND SERIAL DATA TO P0 
	CLR RI 			;CLEAR RI SINCE CPU DOES NOT 
	RETI 			;RETURN FROM ISR 
TRANS: 	CLR TI 			;CLEAR TI SINCE CPU DOES NOT 
	RETI 			;RETURN FROM ISR 
END