The script I wrote is here:
http://raysfiles.com/os/TestOSManual.html
the meaning of each parameter should be pretty obvious. Since it’s Javascript, you do need to keep the browser window active, if you navigate away the script may stop running. I just open it in a spare computer and leave it alone. I’ve tried this script on an OS3 with ethernet module, and it has run 5 hours so far, no issue observed yet.