INCREMENTAL ENCODER : 
Puretronics offers Incremental Hollow Shaft Encoder model FNC 100H.
     The incremental encoder provides a pulse for each incremental step , in it's rotation and the incremental encoder does not output absolute position, it can also provide high resolution at a reasonable price i.e. an incremental encoder with a single code track, its known as a tachometer encoder, generates a pulse signal whose frequency indicates the velocity of displacement. An absolute encoder has multiple code rings with various binary weightings which provide a data word representing the absolute position of the encoder within one revolution. This type of encoder is often referred to as a parallel absolute encoder. An incremental encoder works differently by providing an A and a B pulse output that provide no usable count information in their own right. Rather, the counting is done in the external electronics. The point where the counting begins depends on the counter in the external electronics and not on the position of the encoder. To provide useful position information, the encoder position must be referenced to the device to which it is attached, generally using an index pulse. The distinguishing feature of the incremental encoder is that it reports an incremental change in position of the encoder to the counting electronics.

Features:
1)Industry 100mm Standard Size
2)Through Hollow Shaft 
3)Robust mechanical and electrical construction
4)Protection to IP65
5)Pulse 1024-4096 
6)Frequency 200kHz