Many companies make absolute encoders for motor drives some can output an optional incremental track . my question is why is that needed since the encoder have a BiSS interface that can go as high as 10Mbit/s .
for example : https://www.kuebler.com/usa/prod-sen-multiturn.html
I have read on this site somewhere : Magnetic Encoders - Tips and Tricks
Qoute :" I wouldn't recommend closing a velocity loop on absolute position feedback but rather use quadrature signals"
If this is true then my initial guess is that the cascaded Closed loop drive use Absolute output for position loop and incremental for speed loop .
But why ? It doesn't make any sense especially that absolute encoder have much higher single turn resolution (up to 17bit and even 21bit) which can be really helpful for controlling motor at very low speeds.