Measurement Computing WaveBook rev.5.3 - Manual (Page 152)

G-2 Glossary 969597 Data Acquisition
Digital A digital signal is one of discrete value, in contrast to a varying signal. Combinations of binary
digits (0s and 1s) represent digital data.
Digital-to-Analog
Converter (DAC)
A circuit or device that converts digital values (binary bits), into analog signals.
DIP switch A DIP switch is a group of miniature switches in a small Dual In-line Package (DIP). Typically,
users set these switches to configure their particular application.
Differential mode The differential mode measures a voltage between 2 signal lines for a single channel. (Also see
single-ended mode).
Differential mode
voltage
Differential mode voltage refers to a voltage difference between two signals that are referenced
to a common point. Example: Signal 1 is +5 VDC referenced to common. Signal 2 is +6 VDC
referenced to common.
If the +5 VDC signal is used as the reference, the differential mode voltage is +1 VDC
(+ 6 VDC - +5 VDC = +1 VDC).
If the +6 VDC signal is used as the reference, the differential mode voltage is -1 VDC
(+ 5 VDC - +6 VDC = -1 VDC).
Encoder Mode The encoder mode allows the WBK17 to make use of data from optical incremental quadrature
encoders. When in the encoder mode, the WBK17 accepts either differential or single-ended
inputs and provides power for up to four encoders. When reading phase A, phase B, and
index Z signals, the WBK17 provides positioning, direction, and velocity data.
ESD Electrostatic discharge (ESD) is the transfer of an electrostatic charge between bodies having
different electrostatic potentials. This transfer occurs during direct contact of the bodies, or
when induced by an electrostatic field. ESD energy can damage an integrated circuit (IC); so
safe handling is required.
Excitation Some transducers [e.g. strain gages, thermistors, and resistance temperature detectors (RTDs)]
require a known voltage or current. Typically, the variation of this signal through the
transducer corresponds to the condition measured.
Gain The degree to which an input signal is amplified (or attenuated) to allow greater accuracy and
resolution; can be expressed as ×n or ±dB.
Gating
In relation to the WBK17, any counter can be gated by the mapped channel. When the mapped
channel is high, the counter will be allowed to count, when the mapped channel is low, the
counter will not count but hold its value.
Isolation The arrangement or operation of a circuit so that signals from another circuit or device do not
affect the isolated circuit.
In reference to data acquisition, isolation usually refers to a separation of the direct link between
the signal source and the analog-to-digital converter (ADC). Isolation is necessary when
measuring high common-mode voltage.
Linearization Some transducers produce a voltage in linear proportion to the condition measured. Other
transducers (e.g., thermocouples) have a nonlinear response. To convert nonlinear signals into
accurate readings requires software to calibrate several points in the range used and then
interpolate values between these points.