You seem to be trying to measure voltage from a mains powered heater. The 9205 is not designed for this, and attempting to do so would be very hazardous. Please see the safety specifications for the 9205 - https://www.ni.com/docs/en-US/bundle/ni-9205-specs/page/specs.html.
Consider using instead the NI-9225. It is designed for high voltage applications and is designed to be safely isolated for mains applications.
