You need to configure the code coverage measurement before using the coverage function.
You can configure the coverage measurement function in the [Coverage] category on the [Debug Tool Settings] tab of the Property panel as follows:
Select whether to use the coverage function.
Select [Yes] to use the coverage function (default: [No]).
This property appears only when the [Use coverage function] property is set to [Yes].
The currently obtained results of code coverage measurements are automatically saved when CS+ is disconnected from the debug tool. The next time it is connected to the debug tool, specify whether or not you want to reproduce the contents of saved measurement results.
Select [Yes] to reproduce the contents of previously obtained code coverage measurement results (default: [No]).
This property appears only when the [Use coverage function] property is set to [Yes].
Specify the code coverage measurement area.
Directly enter the start address of any 1 Mbyte space other than the internal ROM area (0x000000 - 0x0FFFFF) in hexadecimal number (default: [100000]).