An absolute encoder reports a unique position value for every shaft angle, so the drive knows the exact rotor position immediately at power-up without a homing run. On permanent-magnet gearless machines this is essential, because the inverter must know the magnetic pole position to commutate correctly. Absolute encoders use serial protocols such as EnDat or SSI and typically offer 13 to 22 bits of resolution. Incremental encoders, by contrast, only count pulses and lose their reference whenever power is removed.