ENNTEC DMX USB PRO
Under El-Capitan (10.11) there is a built-in FTDI driver which is incomplete. You need to disable the built-in driver and use the official one before the box works properly.
Briefly: 1. Install helper ap to block the built-in kext, 2. Install official drivers., 3. Reboot and use
This PDF describes the process (section 7):
For testing purposes you can use the free “pro utility”:
ENTTEC Software (on sidebar)