By default, DMX will be enabled. This means as soon as a fixture is patched onto universe 1, DMX will be output from DMX port 1.
All FLX range consoles have two DMX Outputs on the rear of the console. By default, DMX port 1 outputs Desk Universe 1 and DMX port 2 outputs Desk Universe 2 (on 1 Universe FLX S consoles, both DMX Outputs output Desk Universe 1).
Within the DMX tab, you can choose to disable DMX Output, if you are not using the physical DMX ports and transmitting DMX over Ethernet instead.
You can also change the Transmission between Continuous or Delta. Continuous transmission will result in DMX data being sent at a steady refresh rate, and is the default option. FLX consoles transmit at 33Hz, and FLX S consoles transmit at 29Hz.
Changing the Transmission to Delta, will result in the console sending DMX "updates". This means DMX frames will be sent whenever there are level changes on the console. If you are controlling a fixture that doesn't seem to be responding correctly, change the Transmission to see if the fixture prefers the change in frame rate. If it does, your fixture is not truly DMX compliant.
If you have configured individual Desk Universes, you can press the Reset to Defaults button to reset the DMX Outputs to their default settings.