How to Setup HART_Field_Val versus Field_Val Alarm?

Hello, 

How can I setup an alarm to activate if my AI block hart_field_val (Hart value) and field_val (4-20mA value) is different by about 3%?   I have a level transmitter and I want an alarm when the HART and 4-20mA Pv is different by 3%

I am thinking HART_ERRORS (Ignore PV out of limits) will let me set this, but how do I define the limits.

Thank you