The comparator mode is an optional procedure to get a PASS/FAIL result for a cable test.
Besides measuring of current or voltage in the measurement mode quantitatively (via CMU* resp. VMU* - see measurement units) the comparator mode can verify reaching a certain value by a lower-/higher comparison qualitatively.
This method is faster than the actual measurement since the analysis of the test results can be cancelled and this way the algorithm is simplified. It is used when certain characteristics of a component (e.g. resistance lower than a defined value) need to be validated. If the component has to be measured exactly, the component test needs to be done with the help of a RLC measurement.
*CMU = Current Measurement Unit
*VMU = Voltage Measurement Unit