MacOS energy-saver setting

Instructions for setting MacOS' sleep setting so that the drive will not sleep.

Mac OS include an Energy Saver feature that can cause hard drives connected in or to the computer to spin down after a period of inactivity. If Mac OS sends a command to spin down to an external drive, the drive may stop being detected by the computer. 
To ensure that the Mac does not send a command to spin down your external drive, please see this article from Apple support.

Uncheck the Put the hard disk(s) to sleep when possible box in Energy Saver.