Absolute indicates the position of the rotor or shaft referenced to a fixed starting position. If power is turned off and then on, the encoder recalls the position correctly. It may output the position information on a set of output wires (parallel), or it may output the absolute position using a communications bus, such as Profibus or DeviceNet. Absolute encoders can be single-turn or multi-turn. For more information, Wikipedia:  http://en.wikipedia.org/wiki/Rotary_encoder

Absolute Position indicates the position of a rotor or shaft referenced to a fixed starting position. Resolvers and absolute encoders can provide absolute position feedback.

Encoder accuracy is the ability of or limit to the encoder to repeat the exact same signals, given the exact same mechanical position.  Accuracy and resolution may be independent--an encoder can have higher accuracy than resolution, and vice versa.  Avtron incremental encoders are typically accuracy rated at +/-1 count of their resolution; Avtron absolute encoder accuracy varies by model.

CANopen is a fieldbus used by Avtron absolute encoders to report position and speed to a controller.  CANOpen uses a 4 wire main bus+drop wiring system (CAN).  CANOpen is hardware-identical to DeviceNet and J1939, but the encoder messages sent are different.  For encoder communications, SSI, Ethernet, or Profibus may be faster than CANOpen.  For more information on CANopen-Wikipedia:  http://en.wikipedia.org/wiki/Canopen

This is the sine-cosine encoder equivalent to PPR. It indicates the number of sine waves output per revolution, and does not count the cosine waves. Some vendors also use CPR as an equivalent to PPR for digital incremental encoders.

DeviceNet is a fieldbus used by Avtron absolute encoders to report position and speed to a controller.  DeviceNet uses a 4 wire main bus+drop wiring system (CAN).  DeviceNet is hardware-identical to CANopen and J1939, but the encoder messages sent are different.  For encoder communications, SSI, Ethernet, or Profibus may be faster than DeviceNet.  For more information on DeviceNet-Wikipedia:  http://en.wikipedia.org/wiki/Devicenet

A device which indicates position and speed via a set of digital outputs. Incremental encoders output quadrature (A Quad B) signals, and may add a marker pulse once per revolution.  Absolute encoders typically indicate position via a digital message, a set of parallel outputs, or analog values.

A Fieldbus (communications wiring hardware and software standard) is used to carry absolute encoder signals to the control system.  It may do so automatically on a clock signal input to the encoder (SSI), or in response to a message (ex:  Profibus, DeviceNet).  For more information on fieldbuses:  Wikipedia:  http://en.wikipedia.org/wiki/Fieldbus

GSD files are text files used in Profibus configuration to instruct the master/scanner device of the information coming from each device (bytes/words/meanings).  The user of Avtron encoders downloads the file, then adds it to his configuration software.  Then he can add Avtron absolute encoders to his bus configuration.  Avtron absolute encoder GSD files are found in the Documents tab for each encoder, on the product page.

Hiperface is a proprietary encoder communications system.  Hiperface encoders are only manufactured by one company.  Most devices that support Hiperface also support SSI, an open vendor protocol supported by most controller manufacturers, and used by Avtron absolute encoders.

J1939 is a fieldbus used by Avtron absolute encoders to report position and speed to a controller.  J1939 uses a 4 wire main bus+drop wiring system (CAN).  J1939 is hardware-identical to DeviceNet and CANopen, but the encoder messages sent are different; J1939 is primarily used on mobile vehicles.  For encoder communications, SSI, Ethernet, or Profibus may be faster than J1939.  For more information on J1939-Wikipedia:  http://en.wikipedia.org/wiki/J1939

Light Mill Duty encoders are designed for industrial applications but must be protected from contamination, temperature cycling, and physical force, including shock, vibration, and bearing loads. Examples include AV20, AV25, HS25A, and HS35A models.

Typically an IR LED or laser which shines through or on the optical disk of an encoder. The light source is received by the optical sensor.

M12 (12mm) connectors are a screw or push-on style connector used by Avtron incremental and absolute encoders.  There are different pin quantities, pinouts, and keying, depending on the vendor style supported by the product.  M12 mating cables are typically overmolded, rather than field-solderable, such as MS connectors, or screw terminals, such as EPIC connectors.

M23 (23mm) connectors are a screw or push-on style connector used by Avtron incremental and absolute encoders.  There are different pin quantities, pinouts, and keying, depending on the vendor style supported by the product.  M23 mating cables are typically overmolded, rather than field-solderable, such as MS connectors, or screw terminals, such as EPIC connectors.

Magnetic and magnetoresistive encoders typically use a magnetized rotor with north and south poles lined up around the perimeter of the disk. A magnetoresistive sensor detects the transitions, and these are the counts or pulses generated by the encoder. Magnetic encoders withstand dirt, dust, water, and temperature changes far better than optical encoders.

A magnetized disk with multiple north and south poles lined up around the perimeter of the disk. A magnetoresistive sensor detects the transitions and generates the pulses generated by the magnetic encoder.

An Optical Disk is typically a glass, metal, or plastic disk with fine lines or slots etched around the perimeter that interrupt the beam of light from the light source to an optical sensor. Optical disks can be quite fragile. Avtron uses only shatterproof optical disks with Wide-Gap technology.

An Optical Encoder typically uses a light source shining through, or reflecting off, an optical disk with lines or slots that interrupt the beam of light to an optical sensor. Electronics count the interruptions of the beam and generate the encoder’s output pulses.

Optical Sensors are typically phototransistors or other light sensors which sense the light emitted by the light source, as interrupted by, or passed through, the optical disk.

Pulses Per Revolution. Most Avtron encoders output quadrature pulses, with four times as many lines as pulses. Often lines can be counted in the drive/speed controller for higher resolution applications.

Resolution describes how many individual slices or positions can be reported by an incremental or absolute encoder.  For incremental encoders the number of PPR (pulses per revolution) expresses resolution; for absolute encoders, PPR, or counts per turn or bits of resolution may be listed.

Many encoders come sealed from the factory, but as they are temperature cycled, the air inside expands and contracts at a different rate from the air outside the encoder. This puts pressure on the seals of the encoder and eventually breaks them down, creating an unobstructed path to the inside of the encoder. Likewise, external pressure (wash-downs, submersion) creates the same path. If an encoder has seal failure, contaminants get into the encoder and cause errors in optical encoders. Avtron heavy mill duty and severe duty encoders are highly resistant to seal failure, and feature magnetic technology to ignore most contaminants.

Single turn refers to absolute encoders--the encoder accurately reports the position within 360 degrees of travel to the resolution specified.  Multiple turns are ignored--multiturn absolute encoders are required to track and report position over multiple turns as well as the position within 1 turn.  Avtron absolute single-turn encoders are more durable because they don't use glass disks.  For more information about absolute rotary encoders:  Wikipedia:  http://en.wikipedia.org/wiki/Rotary_encoder

SSI (Synchronous Serial Interface) is a fieldbus used by Avtron absolute encoders to communicate speed and position to a controller.  SSI is extremely simple and fast.  SSI is also an effective, open vendor alternative to proprietary encoder fieldbuses such as EnDAT and HyperFace.   For more information about SSI-Wikipedia:  http://en.wikipedia.org/wiki/Synchronous_Serial_Interface

The portion of the shaft (often on the non-drive end of the motor) used to mount an encoder. To add an encoder to a motor or other shaft that lacks enough extra shaft length to install the encoder, an additional shaft length is added. The stub shaft is threaded into the center of the motor shaft, or the existing motor shaft is enclosed in a sleeve that grips the shaft. Avtron offers many standard and custom stub shafts.

Total Indicated Runout. This is a measurement of how much a shaft wobbles with each revolution (shaft runout).

A type of anti-rotation arm used to mount hollow shaft encoders to large frame motors. It features a threaded rod for adjustable radius.

Wiegand wires generate a pulse of electricity in a coil as a magnet passes near the wire.  Wiegand wires are used in Avtron absolute magnetic encoders to self-power the multi-turn counting engine, so even if the encoder has no power when turned, the absolute encoder correctly reports the number of turns and position.  This allows Avtron to eliminate the glass disks and gears that cause failures in other absolute encoders.  For information on the Wiegand effect-Wikipedia: http://en.wikipedia.org/wiki/Wiegand_effect , Wiegand wire: http://www.epanorama.net/sff/Power%20Electronics/Transformers_and_Magnetics/Magnetics%20-%20Wiegand%20Wire.pdf