Low peak output with Phoenix Tuner

Using Phoenix Tuner with TalonFX controllers and our found peak output is 7,000 units / 100ms under our calculated. We have a step down gear ratio of 1.25 : 1.00 and we’re using Talon FX (Max RPM 6380, Units per sensor rotation 2048). Following the CTRE guide we used an equation (MaxRPM / 600) * (UnitsPerSensorRotation / GearRatio) — we put in (6380 / 600) * (2048 / (1 / 1.25)). This gives 27221.33333. Essentially the problem is when we turn on the motor (with a minor load) it peaks at 20,000 units /100ms which is significantly less than the calculated peak. Any idea where we could be going wrong?

It would be interesting to see the % output. If the % output is 100% that means that you’ve effectively reached the maximum speed of the mechanism under that load. 6380 RPM is the free speed (e.g. the speed with no load) of the motor, and you stated you do have a load attached, so it won’t reach that speed.

The other thing to keep in mind is that your gear ratio should NOT be factored in assuming you’re using the integrated sensor.
The integrated sensor is measuring the Falcon shaft and so it isn’t affected by your gear ratio at all. Where you would factor in gear ratio is if you’re trying to calculate wheel speed from your motor shaft speed.

Without gear ratio in the equation the maximum speed of a Falcon (calculated from max free speed of 6380 RPM) is 21,777 native units per 100ms.


This is incredibly helpful thank you!

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