Which chart update mode should be used to compare old and new data separated by a vertical line?

Using a Sweep Chart update mode is appropriate for comparing old and new data separated by a vertical line because this chart continuously displays data over time, allowing you to visualize the transition and changes between the older and newer sets of data. The Sweep Chart creates a persistent visual representation of the data, showing past and present values distinctly.

This is particularly effective for monitoring trends as it does not just overwrite old data but instead sweeps the old data to the left while introducing new data from the right, making a clear demarcation between old and newly acquired information.

The other options have different purposes: a Strip Chart is more suited for viewing data over a longer period without abrupt changes, the Scope Chart is primarily used for displaying waveforms and may not provide the visual separation for comparison, while the Step Chart visualizes data as discrete steps and does not facilitate the same kind of temporal comparison inherent in the Sweep Chart's design.