on our robot, we are using a encoder on a versaplantary gearbox. It says on the website, that it connects to a Can Talon SRX using the data cable. soo does the motor attached to the encoder need to be connected to the Talon connected to the encoder.
Thx.
That’s traditional 
If an encoder is attached to a Talon SRX, then it’s for the purpose of controlling the motor. What better place to control it from than the motor controller responsible for the motor?
If you don’t own a Talon SRX, then the encoder can be connected to the roboRIO, and the motor controller can be directed from your code directly.
That makes a lot of sense.
Thx.