1)When I start FM without connecting cable to com port,the usual window of "reset the device"pops up & remain.
But the moment try to connect cable to unpowered 8051 board the unusual message i.e. unable to connect....comes on the screen.
One more thing if I remove MAX232 Chip and start FM it waits for resetting the device.

And more interestingly when I put MAX232 chip from my older tested board everything works fine.
That suggests MAX232 ic is faulty. But I tried out by changing almost dozen Ics. But system works with only with the older Ic.
I am confused... It never happenned.
2)My program doesnot write to rs232 port as it works as a slave in modbus environment.
3)My rs 232 port has 3 wires rxd/txd/ground.