Thanks Eriks for your reply...I actually figured out the reason for this.

First off rs232 code for this is \r*pow=on#\r. This is the correct way to write it.

Secondly the pins on the rs232 of the BenQ is exactly the same as the rs232 on the cat5 to the xp-6. So inorder for the BenQ and XP-6 to communicate I switched the the RX and the TX on cat5 connector. so the BenQ has RX on pin 3 and TX on pin 4, I did TX on pin 3 and RX on pin for to go to the XP-6. This way the XP-6 will receive the BenQ on transmission and vise versa.

Hope this will help anyone out there who has the same issue.