On CSM (3.3.1) under Device View/Platform/Security/Blocking/General Tab.
There is an option "Enable Blocking" which is on by Default.
If the IDPS device (4270) is INLINE by configuration, does this "Enable Blocking" checkbox
act as the master control that determines whether the sensor will BLOCK or just MONITOR ?
CSM is managing and monitoring software but until you do the configuration on IPS itself it can not take a blocking action
There are a lot of steps involved in this like Configuring the blocking device, most important.
Check this for more information
http://www.cisco.com/en/US/docs/security/ips/7.0/configuration/guide/cli/cli_blocking.html#wp1065441
Regards,
Sachin