Technical » Glossary

Glossary

Absolute shaft encoder

Shaft encoder that transmits unique coded data for each increment.

Analogue signal

A signal whose level alters continuously.

ASIC

Application specific integrated circuit.

Bandwidth

Frequency range for output signals.

Baud rate

Rate of data transfer(bits per second).

Binary

Two logical states(yes/no); the basis of binary data-processing systems.

Bit

Abbreviation for "Binary digit"; the smallest unit of information of a binary system, whose valuse can be 1 or 0 (yes-or-no decision).

Bus Cycle

Time needed for polling every slave by the bus master.

Byte

Sequence of 8 bits.

CANopen

Layer 7 protocol based on CAN.

Channel

Single track on which 1 or 0 is outputted.

Data Bus

System of lines over which data are transferred electronically in parallel or serially.

DIN

Deutsche Industrie Norm (German Industrial Standard).

EDS-File

Electronic data sheet. This is a file with the device specific parameter description and is provided by the manufacturer of a DeviceNet or CANopen device.

EEPROM

"Electronically rasable Programmable Read-Only Memory" chip.

EMC

Electromagneticcompatibility.

Encoder power

Supply voltage provided for the shaft encoder.

EPROM

"Erasable Programmable Read-Only Memory" chip, which can be erased with ultraviolet light, after which new data can be written into it.

Gray code

A special binary code that changes only one data bit per measuring srep at a time. It id used with absolute encoders.

Harmonic Distortion

Measurement deviation for a position approached from opposite directions.

Incremental measuring system

Measuring method in which the variable is formed by counting increments(measuring steps).

Incremental shaft encoder

Shaft encoder which transmits an electrical signal(yes/no) for each increment, determined by the marked disc.

Integrated coupling

Flexible coupling built into shaft encoders.

Jitter

Change in the phase angle between Channel A and B within one revolution(360°).

Measuring wheel

A wheel that, mounted on a shaft encoder, converts a linear motion into a rotary motion.

Multi-turn shaft encoder

Shaft encoder which transmits the number of shaft revolutions as well as the angular position of the shaft.

NPN input/output

Transistor input/output circuit implemented with an npn transistor, and thus hegative switching.

Offset

For programmable absolute shaft encoders: the offset value is added to the value of physical position. As a result you get a relative shift of the output value(output value = position value + offset value).

Parallel interface

Transfer point at which the data are transferred in parallel over several lines.

PNP input/output

Transistor input/output circuit implemented with a pnp transistor, and thus positive switching.

PVC

Polyvinylchloride; plastic coating of device cable.

PTB approval

Approval for use by the Physikalisch-Technische Bundesanstalt, the German government materials testing institute.

RAM

"Random Access Memory" chip; this memory can be read from, written to, and erased freely. When the power goes off, it loses its information.

Resolution

Number of increments per revolution(rotary) or distance between two increments(linear).

Reversal error

Deviation in reading of a position when approached repeatedly under identical operating conditions.

RS 422

Standardised interface for unidirectional point-to-point connections; voltage difference 7 V DC max.

RS 422/485

Interfaces for serial data transfer with specification to EIA standards.

RS 485

Like RS 422, however as a bidirectional bus interface.

Sampling frequency

Number of signal periods per second. The maximum sampling frequency limits the speed of incremental measuring systems.

SSI

Synchronous-serial Interface; standardised interface for serial data transfer.

TPE

Thermo-plastic polyester elastomer; plastic coating of device cable.

Tristate

Control input; switches the output either to active or to high impedance.