How to handle system errors in XI using BPM? please help!

Hi Experts,

I have a requirement where I have to handle system errors. For example when I am making RFC call using RFC adapter if the remote destination is down then I have create a understandable error message and store it in another SAP table.

How to handle it? I am using BPM. I can see that there is "Exceptions" in the send step. How to use this?

Thanks

Gopal