how to set or get multiple messages using devctl structure. Plz provide with the basic code…thanks.

Can you elaborate your question. What does multiple messages mean?

Do you mean multiple messages as in multiple IOV structures to accomodate more data?
If that is the case, you should probably use MsgReadv() if you know the type of the message you have received to get all of the data in rather than assuming it all fits in the message by using _DEVCTL_DATA macro.