If using block mode, your application won't collect data until the device has triggered (If the trigger has been set)
You will know what value you have set the trigger at, but won't know what voltage levels are being sampled.
The application will be waiting for the callback to set the g_ready flag to show that data is available.
You can decide what to do if the trigger doesn't occur.
If using streaming mode, you will know what value you have set the trigger at, and will be able to collect data. The callback will set the triggered parameter to show if the trigger occurs.
You can monitor the received signal, and decide what to do.