Why does my Honeywell 6160 say 'Field?'

The only time your Honeywell 6160 alphanumeric keypad displays 'Field?' is when you are in programming. Whether or not you meant to go into programming is irrelevant. You are now here, so what next? Well if you need program anything do it now by using the alarm system's programming manual. When you are ready to exit programming mode simply enter *99 on the keypad. Be patient. After you press *99 it may take a several seconds to exit you out of data programming mode. 

This will kick you back to the standard home screen where it will display the current status of the system (i.e. Ready to Arm). Now you can arm, disarm, toggle chime, etc. If you are not sure how you got into programming in the first place, you may want to learn how to get into programming on a 6160 keypad.