Suresh,
Page 4-6 in the NI 6052E User Manual (link available below) provides the following description of the external expansion connector:
"The external expansion connector, which connects to SCXI in serial mode, is located on the back panel of the DAQPad-6052E. Using the external expansion connector does not use any AI channels, but does use DIO0, DIO1, DIO2, DIO4, and PF17/STARTSCAN."
NI 6052E User ManualGood luck with your application.
Spencer S.