Dear Raghu,
Thanks
I am not going to use telephone line to control the
devices at this stage.Here is the full details of the project

Hardware:
Pc serial Port is connected to P89C51RD2 via Max 232.
The same serial interface is used for Flash programming.There is a change overswitch"ISP/NORMAL" When in ISP mode: program can be loaded to uC. In NORMAL mode by pressing push button the respective LED glows.

uC is loaded with simple program:P1 port as input and P2 as Output port.working OK.

Now would like to add :
Visual Basic User Interface<----->P89C51RD2<----->I/O modules

1. User Interface: There are 8 ON & Off Switches.
2. P89C51RD2: Port P1 is Input Port and P2 is output port
3. I/O Module: 8 inputs (push buttons) and 8 outputs (LEDs)

Sending data to P89C51RD2

MsComm1.ComPort = 1
MSComm1.Settings="9600,N,8,1"
MSComm1.PortOpen = True

How to send the data or command to the uC and make the uController to respond to the data ? In this case by sending data to make the LEDs glow.


Please help me out to complete this project.


Regards

Harnam