After a long wait for latest android SDK, now the Android Marshmallow 6.0 is available, 2 major enhancement for Android 6.0 is

Android Platform Change:
Final Permissions User Interface — we updated the permissions user interface and enhanced some of the permissions behavior.
API Change:
Updates to the Fingerprint API — which enables better error reporting, better fingerprint enrollment experience, plus enumeration support for greater reliability. 

currently the Honeywell CN51 is running on OS Android Jelly Bean 4.1.

below is the latest version on Android OS.

Jelly Bean (4.1–4.3.1)
KitKat (4.4–4.4.4, 4.4W–4.4W.2)
Lollipop (5.0–5.1.1)
Marshmallow (6.0)