Just like Yosemite, El Capitan requires kext driver signing. How this can be disabled in OSX 10.11 is changed however. - See more at: https://www.kiwi-electronics.eu/blog?journal_blog_post_id=7#sthash.VKyAY1nx.dpuf
To get the CH340 drivers to work in El Capitan you need to use the new tool csrutil as follows:
- Reboot and press CMD+R immediately after hearing the startup sound to boot to Recovery Mode
- Open Terminal
- Execute the following command: csrutil enable --without kext
- Reboot
See more at: https://www.kiwi-electronics.eu/blog?journal_blog_post_id=7#sthash.VKyAY1nx.dpuf