rtlsdr_read_sync failure

Hi, I need to get a few traffic data bytes ~ 16 B from my dongle. libusb's bulk transfer and therefore rtlsdr_read_sync, will fail with -8 if used with less than 1024 B. Can anyone think of another way to read them? (async also uses libusb's fill_bulk_transfer :-() I could possibly use rtlsdr_read_array, except that i don't know the block and address that I need to use for traffic data :-( Thanks, Nikos