SMART check on external USB hard disk on macOS

Solution 1:

If you read down that list, see how many have been tested to work on macOS… I can't find any.
It's generally accepted that you can't get SMART data over USB on Macs, because they don't provide SCSI passthrough.

There are some exceptions requiring an extra plugin available from the makers of DriveDx, who note…

If you want to perform external drive diagnostics on OS X – currently there is only one option – you can install 3rd party kernel extension – SAT SMART Driver. SAT SMART Driver is free open source project (published under Apple Public Source License) by Jarkko Sonninen. It is hosted on GitHub.

If you want the driver, access it through the DriveDx page linked above, as they link to various versions for different purposes. Also linked are how-tos for specific OS versions.

smartmontools refers to this on their USB devices and smartmontools page…

The ​OS X SAT SMART Driver provides access to SMART data for SAT, JMicron and Sunplus capable USB and Firewire devices on Mac OS X. On OSX El Capitan (10.11+) you may need a signed driver, which can be downloaded from the ​DriveDx website. Note that this does not support 48-bit ATA commands (-l xerror) or non-SMART ATA commands (-s apm,N). Full USB support would require SCSI pass-through support which does not yet exist on Mac OS X.