H. Kuhnke Ltd, Romsey, UK
Tel: +44 (0)1794 514445 Email Us

 

Glossary - The Encoder Company

Absolute Rotary Encoder
An electro-mechanical device which converts angular position into digital data that is retained when electrical power is removed. Can be also used to determine linear position, and speed/acceleration.

ASIC
Application Specific Integrated Circuit

Baud Rate
Rate of data transfer (bits per second). Often expressed in Mbaud i.e. 12 Mbaud.

BiSS
Bidirectional Synchronous Serial Interface. A protocol for serial data transfer between an absolute encoder (slave) and it's controller (master). Supercedes SSI (Synchronous Serial Interface) with added features, greater speeds over longer cable runs etc. BiSS "masters" can communicate with up to 8 encoder slaves. Up to 10Mbaud.

Byte
A sequence of 8 bits.

BLDC
Brush Less DC Motor

Incremental Rotary Encoder
An electro-mechanical device which converts angular position into data (normally pulses). Can also be used to determine linear position, speed & acceleration. Does not retain positional data on removal of power.

Resolver
A device for monitoring speed and angular position of an electric motor, usually integrated on the rotor-shaft and sometimes known as a motor feedback controller.

CANopen
A fieldbus protocol which any manufacturer can elect to interface with. From Controller Area Network originally developed by Robert Bosch GmbH, originally for automotive (in-vehicle) applications, now widely used in European Industry.

CAN Layer2
Used in the early days of CANbus when there was no standard profile. Today most new applications use CANopen.

Complementary
An electronic circuit with encoder outputs to invert two channels and express a voltage difference between two lines thus removing interference along transmission cables that connect an incremental encoder with its controller.

Comcoder
An encoder with incremental and commutation outputs fitted to the end shaft of an electric motor for feedback.

CSA
Canadian Standards Associations (an approval body)

Data Integrity
Correspondence of data with the reality they describe.

DeviceNet
A fieldbus protocol which any manufacturer can elect to interface with. Introduced by Allen Bradley Corporation (Rockwell Automation) and commonly found in North America. It is based on CAN.

DIN
Deutsch Industrie Norm (German Industrial Standard)

Dynamic Behavior
A term used to describe a way in which a function is triggered by a pulse (the pulse edge only), whilst pulse width is disregarded.

EDS File
Electronic Data Sheet. In our encoder industry this is a file for a particular device/product with specific parameters and description for use with DeviceNet or CANopen. Hengstler Encoders for these fieldbus protocols, come with an EDS file which can be downloaded from TheEncoderCompany.co.uk

EPROM
"Erasable Programmable Read-Only Memory" chip which can be erased with ultra-violet light after which new data can be written to it.

EMC
Electromagnetic Compatibility

Gray Code
A special binary code that changes only one data bit per measuring step at a time. It is used with incremental encoders, to determine the direction of rotation of a rotary encoder with quadrature outputs.

GSD File
The parameterisation file used to identify a PROFIBUS slave. You can download the Hengstler AC58 PROFIBUS absolute encoder GSD file from The Encoder Company website.

 

INTERBUS
A fieldbus protocol which any manufacturer can elect to interface with. Commonly used by Phoenix Contact in Germany (also INTERBUS-S and INTERBUS Loop for actuator sensors).

Interpolation
Scanning of a sine-wave signal to increase resolution by generating intermediate position values.

Jitter
Change in the phase angle between Channel A and B within one revolution (360°), when used with incremental encoders

LSB
Least Significant Bit

Measuring Wheel (Encoder Use)
A wheel that, mounted on a shaft encoder converts linear motion into rotary motion.

MSB
Most Significant Bit

MTBF
Mean Time Between Failures

Multi-Turn Shaft Encoder
Rotary shaft encoder which transmits the number of revolutions as well as the angular position of the shaft. Can be incremental or absolute.

NPN Input/Output
Transistor input/output circuit implemented with an NPN transistor and thus negative switching.

PROFIBUS
A fieldbus protocol which any manufacturer can elect to interface with. First developed in Germany in 1986 by a consortium of companies under the direction of the German Department of Education & Research BMBF. Originally known as PROFIBUS FMS (multi-master), followed by PROFIBUS DP (single-master), and extended to PROFIBUS PA (intrinsically safe). Considered market leader in Europe. Please refer to the Fieldbus section of the Encoder Company website.

PROFINET
An ethernet based automation fieldbus, introduced in 2005 which extends ethernet speeds and network capacity direct to I/O slaves. Widely expected to grow in popularity as equipment manufacturers introduce more product.

Push/Pull
A term used for an electronic circuit used to drive the electrical outputs of incremental encoders. Creates loads from positive & negative current. With Hengstler encoders uses 10-30VDC and has advantages over RS422. To ensure maximum immunity from EM "noise" you should always specify Push/Pull Complementary.

Quadrature
Quadrature outputs (of an encoder) are two, called A and B which are in the form of pulses, 90 degrees out of phase. By reading the status of one pulse and comparing with the status of the other, a 4 bit signal is generated, typically 00 ,01, 11, 10. This is decoded(graycode) to determine direction, and a count up or count down pulse is generated. Typically, with an incremental encoder this decoding takes place at the counter.

Resolver
A type of rotary electrical transformer used for measuring degrees of rotation. It is considered an analogue device and has a digital counterpart, the absolute rotary encoder.

RS422
A standardised interface for unidirectional data transfer. When applied to Hengstler encoders it will be used with incremental encoders, with 5VDC supply, and comprises twisted pairs of wire for data and clock, plus power. A & B channels have complementary outputs within this physical layer.

SDO
Server Data Object (in CAN networks)

Sense
The sense lines, (sense VCC and sense Gnd) enable measurement of factual encoder voltage, whilst ignoring and compensating for supply line voltage drops.

SSI
Synchronous Serial Interface. A protocol for serial data transfer, say between an absolute encoder and its controller. The physical form comprises 2 twisted pairs (data and clock) plus power within a shielded cable. Data is one way. SSI has been superced by BiSS; Bidirectional Synchronous Serial Interface which is reverse compatible with the same physical layer.

UL
US approval (Underwriters Laboratories).