Siko AH3650M Absolute Encoder

Rotary encoders based on the absolute measuring method

Absolute rotary encoders also called Absolute value encoders, are encoders which unambiguously encode every shaft position and display it as a position value. Thus, absolute value encoders are able to deliver unambiguous position values from the moment they are started. For instance, an absolute rotary pulse encoder detects its position exactly also after restart even when it has changed in the de-energized state. Therefore, with the absolute measuring method compared to incremental rotary encoders, there is no need for time-consuming reference travels after machine start or after loss of supply voltage.

Absolute single-turn rotary encoders

Single-turn rotary encoders are angle encoders, which are able to absolutely acquire and output the position within one revolution (360°. These encoders are particularly suited for applications where a swivel movement is to be acquired absolutely. ‘The availability of very small design and their ability to acquire absolute angle positions at especially low cost is another great advantage single-turn encoders from SIKO.

Absolute multi-turn rotary encoders

If more than 360° are to be scanned absolutely, a multi-turn rotary encoder is required. The absolute multi-turn rotary encoders from SIKO do not only detect the position exactly within one revolution but count the number of revolutions in addition. SIKO offers two different technologies. Firstly, via an especially developed durable multi-turn gear where the revolutions of the shaft are stepped down and detected by additional sensors. Secondly, the innovative Energy Harvesting Technology. These particularly small multi-turn rotary encoders detect the number of revolutions contactlessly and without battery and gear above all. A special process within a revolution (no matter how fast or slow) generates energy. This energy is used for an exact detection of the number of revolutions even in the dead state and to store the data.

Just as with the incremental rotary encoders, SIKO offers a wide array of different designs and housing variants of absolute rotary encoders. For example, the rotary encoders can be ordered with a common 58mm flange or with a 36mm housing, which is suitable for applications with confined space. Also, special heavy-duty rotary encoders are available with housings made of stainless steel or aluminum and protection classes up to IP69K.

A wide spectrum of interfaces rounds off the package. Thus, rotary encoders with fieldbus interfaces such as CANopen are available besides serial interfaces such as SSI or analog interfaces.


  • Absolute measurement system
  • Very high resolution
  • Precise positioning
  • Different interfaces
  • Fieldbus interfaces
  • Miniature designs also available in heavy-duty housings


  • Absolute wear-free magnetic encoder
  • Multiturn without gearbox and without battery
  • Current or voltage output interfaces
  • Extremely compact and very robust design
  • IP67 protection class
  • Extensive temperature range -40 … 85° C
  • Optimal price-performance ratio


Frequently being used for precise speed measurement and position monitoring in diverse applications including packaging plants, textile machines, printing machines, woodworking machines or asynchronous motors.


Feature Technical data Additional information
Shaft rustproof stainless steel
Flange aluminum
Housing zinc die-casting
Speed 6000 rpm at protection class IP65, transient for ≤10 min
3000 rpm at protection class IP65, continuous operation
4000 rpm at protection class IP67, transient for ≤10 min
2000 rpm at protection class IP67, continuous operation
Starting torque <0.007 Nm at 20 °C at protection class IP65
<0.01 Nm at 20 °C at protection class IP67
Shaft load rating 40 N radial
20 N axial
Cable sheath PVC ø6.2 ±0.2 mm
Cable bending radius 60 mm static
130 mm dynamic
Mounting type stator coupling mounting type DS1
spring element mounting type DS2
Weight ~0.2 kg


Datasheet : Siko AH3650M Absolute Encoder

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