In order to view the SMART data from external drives, third-party extensions, collectively called SAT SMART Driver, needs to be installed. With the release of macOS 10.13 ‘High Sierra’, Apple has incorporated a new feature that requires a user’s approval before loading new third-party kernel extensions. After the successful installation of the SAT SMART Driver, you will see a dialog like this one appear:

When this dialog is displayed, it means that the SAT SMART Driver kernel extensions were installed successfully. Quit the SAT SMART Driver installer and proceed to the Security & Privacy system preference which is located with the System Preference option under the Apple menu. With the System Preferences window open, select the Security & Privacy system preference circled in the image below:

After selecting the Security & Privacy system preference, you will be presented with this view:

You will notice that a new statement is presented stating that, ‘System software from developer “Micromat, Inc.” was blocked from loading’. In order for the SAT SMART Driver to load and work for external USB and FireWire drives in Drive Scope, you will need to click on the Allow button in the Security & Privacy system preference. Once you have clicked on the Allow button, you will be presented with this dialog:

NOTE: If the Allow button is not responding after you click on the button, restart your Mac and try again.
Click on the Restart button in this dialog to allow the loading of the SAT SMART Driver kernel extensions for your Mac. After clicking on the Restart button, your Mac should proceed with restarting. Once restarted, the SAT SMART extensions will load whenever your Mac starts up, allowing SMART data from external drives to display in Drive Scope.
NOTE: Approval is already granted to the SAT SMART Driver kernel extensions if they were already installed prior to upgrading to macOS 10.13 ‘High Sierra’.