How do I choose and encoder?

To add a close-loop position verification to your system, an encoder must be chosen. For the models that do not have an encoder integrated, it is important to choose the right encoder.

  • Absolute vs. Incremental: An absolute encoder will provide absolute position even after power down. An incremental encoder keeps track of position but needs a point of reference. Arcus products only support incremental encoders.
  • A,B,Z: The 3 signals used for incremental encoders are A, B, and Z. A and B provide the direction and incremental position moved. The Z signals provides a single pulse once per revolution. This can be used to home to a specific location within the 360 degrees of the motor. 
    • There are A, B output encoders, as well as A, B, Z output encoders. If you do not need a Z index, an A, B output encoder will suffice.
  • Output Circuitry: Arcus products accept 0 to 5V TTL signals.
  • Differential vs. Single-ended: Encoders are available in differential or single-ended options. Differential output are necessary if your encoder signal is to travel long distances or in a noisy environment. Before choosing a differential encoder, be sure to check that your product supports differential encoder signals.
  • Resolution: The resolution specifications for an incremental encoder is counts per revolution (CPR). Note that the resolution specification is known as the native resolution. The controller has the ability to interpolate the encoder signals to multiply the effective resolution.

Arcus products provide up to 4X decoding. For example, if a 1000 CPR encoder is selected, the Arcus product can interpolate the signal to 1000 x 4 = 4000 CPR.


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