Connect the USB cable from the Control Surface to one of your NewTek 3Play’s USB ports. Do not extend the supplied cable if possible.
SUPPLEMENTARY QUESTION:
Q: My system has suddenly stopped responding to the Control Surface. What can I do?
A: The foremost reason this might happen is if the cable (or extender cable) you are using between the Control Surface and NewTek 3Play failed to deliver sufficient current consistently. In the short term (if you are in the middle of a show), you can generally resolve this issue by simply unplugging and re-plugging the Control Surface.
However, please note that the use of so-called "USB extenders" is not recommended. Whenever possible, use a single USB cable of the correct length. Each added connector on the signal path is a potential connection problem, and also causes signal ‘reflections’. Such an arrangement may seem to work for a while, then fail unpredictably.
If you are using a very long USB cable (or a poor quality cable), you should supply a powered hub at the end of the cable nearest the Control Surface, then complete the connection with a short USB cable from the hub to the Control Surface (an unpowered hub will be of no help).