The NET+OS 7.5.2 API documentation is integrated into the NET+OS graphical ESP and available only after installation of NET+OS with a valid license key.
In fact the API documentation is a Windows Help file .chm, which you can download and browse through from here:ftp://ftp1.digi.com/support/patches/ApiReference_75.zipunpack and store this locally under Windows. If you open ApiReference.chm locally you should be able to browse through the NET+OS 7.5.2 API.
You will not be able to directly open it from the download link, so extract the .chm file to your desktop or other folder and open it from there!
Last updated: Aug 08, 2017