Hi,
Data Writing Interval is set by user on AppAdmin page, under Tools/Real Time Snapshot Config.
As per the CRS-3.1 release notes...
The following data writing intervals have been added: 5, 10, 15, 20, and 25. You can set the data writing intervals from Cisco CRA Administration by choosing Tools > Real Time Snapshot Config and then choosing the desired value from the Data Writing drop-down list. These new data writing intervals are useful when wallboard data is required to be updated with a refresh interval of less than 30 seconds.
URL for the same is...
http://www.cisco.com/univercd/cc/td/doc/product/voice/sw_ap_to/apps_3_1/english/admn_app/relnote/rel312r2.pdf
Check in Pg.No:7
Regards
Yogi