[Jared Russell]

One quick word of warning...the Talon SRX calculates velocity as "change in position per 100ms". This works well for providing smooth velocity measurements with quadrature encoders (where you are generating tens or hundreds of thousands of pulses per second), but may result in poor velocity resolution with a break-beam sensor and number of counts per revolution. For example, a 5000 rpm flywheel with 2 pieces of retroreflective tape will generate ~167 counts per second, or ~17 counts per 100 milliseconds.

Usually for the latter configuration, you are better off measuring the time period between consecutive rising or falling edges rather than differentiating position over time. You can do this on the RoboRIO, but not on the Talon SRX (at least on current firmware as of today).