output encoder vs. motor encoder plus INI

Our customers can choose between motor encoders / Ini switches and igus output encoders (both incremental angle sensors).

Motor encoder / INI (RL-D-RBT-xxxxx-BC):

+) proven industrial standard, double ended signal transmission (A/A-, B/B-), high resolution (500 signals / motorturn * transmission of the joint)

-) 3 cables per axis (motor, encoder, INI), reverse play of the joint is not noticed, mechanical changes in the joint are not noticed (i.e. temperature, load,..)

Output encoder (RL-D-RBT-xxxxx-BC-AE):

+) cheaper, less cables, easy to replace, we measured better repeatability values for multi axis arms in different use cases (detailed results will be shown in ~6 weeks)

-) not industrially proven, single ended signal transmission (A, B) => danger of signal loss is higher,  EMC not proven

Conclusion: We recommend to use our output encoders for non critical (non industrial) applications, for industrial applications we recommend motor encoders or testing of the output encoder in the given environment.

DOWNLOAD SECTION. New data sheets for output encoders:

englisgh version:  RL-D Sensorik Doku (#5)

german version:  RL-D Sensors Doc (E#5)

data sheets for robolink standard arms (RL-D-RBT-xxxxx-BC-(AE)

igus supplies “electromechanical joint arms“. They consist of:

  • robolink joints with worm gears (RL-D) and strain wave gears (RL-S),
  • igus stepper motors NEMA11, -17, -23 and -23XL,
  • Ini-switches for the Zero-Point definition (BC version) or Output encoders (BC-AE version),
  • connection parts between these joints (folded metal sheets RL-DC)
  • a set of igus cables (5m long) and e-chains for the connection to a control unit
  • OPTIONAL: an adapter for the connection of an Actuator (gripper, suction cup, camera,…)

Please find attached data sheets and STEP data for the different configurations:


“small version” with 2x RL-D-30 and 2x RL-D-20 (payload max. 1 kg, reach ~600 mm)

“big version” with 2x RL-D-50 1x RL-D-30 and 1x RL-D-20 (payload max. 3 kg, reach ~750 mm)

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