Scan

Click on this button will start the search and Comparator Fast works.

When scan begins, you'll see a progress, and the status led's will change from "Free" () to "Busy" ().

This button will hide when scan begins; also some commands and options will be unavailable during the scanning process:

The comparison process can be:

Two-way > default. Compare "From" (source) with "To" (target) and "To" with "From".
From - To > Compare "From" (source) with "To" (target) [Phase 1].
To - From > Compare "To" (target) with "From" (source) [Phase 2]. Please note than this mode don't search for duplicates. Phase 1 is needed for duplicates search.

Disabling some options is necessary to avoid unwanted or mixed results others that what you' re looking for.