TalonSRX arm control with mag encoder? (Solved)

[bsimmons]

Depending on how many rotations the arm encoder does, the absolute function of the encoder will tell you where it is within one revolution, across reboots. Even if it’s more than one, say you had a 2:1 gearbox, you could know what side of the arm it would start on and guess.
However, assuming its multiple rotations, you can use a limit switch to zero the encoder when the robot is booted. ie run the motor in a known direction until the switch is triggered, then set the encoder to zero. That way you have a reference point at which to reset it.

There was a short discussion here:

Encoder on spool

You could use a limit switch to reset your encoder to a known value each time it triggers it, that could help with some of the randomness of it spooling. A thought, does the change in circumference of the wire spooling make a large enough of an error to be a problem? My assumption is that the encoder is mounted on the shaft of the pulley and you are counting rotations and equating the rotations to distance.