Hi Anant,
I think we can not export error messages from RWB in PI 7.0.
The option suggested by Raghuraman may be available in higher versions.
If you want to use RWB, choose message monitoring -> Adapter engine -> Database overview and click on export. It will generate a CSV file.
But in PI 7.0 we don't have Database overview option, so you can't use it.
You can export error messages from Moni as specified in the below screenshot.
--> SXMB_Moni --> Set the filter [From date / To date / Status Group - Errors]
Regards
Bhargava Krishna