[ozrien]

If you set the control mode to Speed, then set() will take the target speed you want. The units are sensor-dependent and better explained in section 17, but it's basically the change in sensor value per 100ms. You can also cheat by using the Self-Test to see what your "Sensor Velocity" reads while driving the motor.

Examples on how to change modes is in Section 3.6. (Section 3.6.3 for Java).

Also after you changed the mode, the Talon SRX will not drive motors until the next call to set(). See Section 16.12 for more info.