A Quad B refers to the set of output quadrature signals from an incremental quadrature encoder to indicate speed and direction, including complements: A, A NOT, B, B NOT (, , , ). Most Avtron encoders offer A Quad B output at no extra cost.  For more information on quadrature- Wikipedia: http://en.wikipedia.org/wiki/Quadrature_phase

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.

Also known as complementary outputs. To ensure that signal noise does not cause errors between the encoder and the controller, many encoders output signals that are driven in exactly opposite directions: when A goes high, A NOT goes low (, ); when A goes low, A NOT goes high. Controllers which see a transition in A, but not in the A NOT signal, would report a quadrature error.

Also known as contaminants, such as water, dirt, dust, oil, and other compounds which enter an encoder through seal failure and can cause optical errors. If the contamination is abrasive, it can also cause bearing failures in the encoder. Modular encoders are very resistant to contamination as they use magnetoresistive sensors and have no bearings.

Refers to a flexible device that is used to link a solid shaft encoder to the shaft to be monitored. Avtron strongly recommends isolated, flexible disk style couplings wherever possible to maximize encoder bearing life. For large axial shaft movement, splined couplings should be used.

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 machined surface (NEMA 56C, NEMA FC) on the non-drive end of the motor is used to mount bearingless or pancake encoders such as Avtron AV56 THIN-LINE II™ encoders. Solid shaft, coupled tachometers also flange mounted using flange adapters, also called flowerpots.

A Flange Adapter provides the NEMA 56C motor mounting face and properly locates the encoder shaft. The encoder shaft and motor shaft are then connected using a flexible coupling. (Drawing "A") Often flange adapters can be eliminated by directly mounting a modular encoder such as an Avtron AV125, AV850, AV56, AV67, AV85, AV115 unit on the motor flange. (Drawing "B")

An encoder that produces pulses in proportion to distance moved or rotated. Incremental encoders can also have a marker pulse Z, Z NOT (, ) once per revolution to provide a position reference. Avtron produces a full range of incremental rotary encoders.

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.

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.

The Marker Pulse occurs once per revolution. The purpose of the marker pulse is to provide a repeatable home position location for positioning applications. The marker pulse is often abbreviated as "ØZ" or "Z" in the USA and "C" or "N" in Europe.

This is a 10 pin military style connector used for encoders.  It includes a set of locking pins and slots instead of the threaded mating system on most MS connectors.  It is also known as "Mini-Twist-Lock", "Bayonet", and "Baldor connector".

This is a 10 pin military style connector used for encoders.  It includes a set of locking pins and slots instead of the threaded mating system on most MS connectors.  It is also known as "Bayonet", "MS Mini", and "Baldor connector".

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 Errors include false pulses, missed pulses, and quadrature errors that are generated when there is any type of contamination (dirt, oil, water, condensation) on the optical disk.

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.

Pulses are also known as counts and are the low voltage output transitions which indicate movement of the encoder. Encoders are rated by resolution or PPR (pulses per revolution). Pulses are not the same as lines.

To determine which direction an encoder is revolving, encoders output quadrature signals: two streams of pulses, A & B, generated at 90° timing angles. (Also called A Quad B) A leading B indicates rotation in one direction; B leading A indicates the encoder is rotating in the opposite direction. Example: “A leads B with clockwise rotation as viewed from the encoder face on an HS45 encoder." Many encoders with quadrature outputs also have complementary outputs: A NOT and B NOT signals.

Failures of the encoder to generate properly formatted quadrature signals. Most typically, these are failures to create the proper 90° signal separation between the A and B channel outputs, with a less than perfect stream of square waves. Most controllers, when presented with a quadrature error, will report a drive fault or encoder fault and then shut down.

A rotary encoder provides position and/or speed feedback information about a rotating shaft.  Rotary encoders may be hollow shaft, no-bearing modular, coupled solid shaft style.  They may provide absolute positioning information, or incremental velocity feedback. Avtron rotary encoders are designed and built to be far more reliable than ordinary rotary encoders. Avtron encoder white papers on our blog provide more details of how and why Avtron rotary encoders are more reliable.

The disk-shaped portion of the modular encoder that is mounted on the motor shaft. Avtron modular encoders use magnetic rotors.

When the rotating disk in an encoder contacts the sensor (optical or magnetic/magnetoresistive), it damages or destroys the sensor. Sensor crashes can be caused by excessive vibration, shaft runout, or alignment problems in encoder mounting. Avtron encoders feature Wide-Gap technology to eliminate sensor crashes.

Solid Shaft encoders are coupled to the shaft to be measured. The solid shaft encoder body is typically C-Face mounted using a flange adapter, or some models can be foot mounted.

Incremental and absolute encoder signals should be carried over twisted pair cables.  Twisted pair cables enable the elimination of external noise signals, as the signals show up as "common mode" noise on both wires in the pair.  The controller wired for differential communication will remove the external noise from the encoder signal.  When wiring Avtron incremental encoders, be sure to wire the complementary signals (ex: A, A/) in one twisted pair.  Do not mix phased signals (ex: A, B) in the same twisted pair.  For absolute encoders, follow the bus recommendations for using the twisted pairs in the required cable type.

Avtron encoders use special optical sensors and magnetoresistive sensors, combined with proprietary circuit designs to allow the sensor to be located much farther from the magnetic rotor or optical disk. This eliminates sensor crashes and makes mounting easy and forgiving of mechanical variation.