data acquisition

100 Pages·2003·1.34 MB·English

DDAATTAA AACCQQUUIISSIITTIIOONN
Prof. Dr. Tuna Balkan
Fall 2003-2004
WWhhaatt iiss DDaattaa AAccqquuiissiittiioonn??
Data acquisition systems are
used by most engineers and
scientists for laboratory research,
industrial control, test and
measurement to input and output
data to and from a computer.
Balkan-Data Acquisition 2
A data acquisition and control
system typically consist of the
followings:
Sensors which measure physical
(cid:122)
variables such as temperature,
strain, pressure, flow, force and
motion (displacement, velocity,
and acceleration)
Balkan-Data Acquisition 3
Signal conditioning, to convert
(cid:122)
the sensor outputs into signals
readable by the analog input board
(A/D) in the PC.
An analog input (A/D) board, to
(cid:122)
convert these signals into digital
format usable by the PC.
Balkan-Data Acquisition 4
A computer with the appropriate
(cid:122)
application software to process,
analyze and log the data to disk.
Such software may also provide a
graphical display of the data.
An output interface, to provide an
(cid:122)
appropriate process control
response.
Balkan-Data Acquisition 5
Physical Transducer Signal
A/D Converter Computer
System Sensor Conditioning
00101011
00111011
10100000
10101010
Physical Noisy Electrical Filtered and 8-bit Resolution 00101011
Variables: Signal Amplified Digitized Signal 11101011
Temperature, Signal
Pressure, Flow,
8-bit Binary
Position,
Code
Velocity,
Acceleration,
Force
Balkan-Data Acquisition 6
In order to sense and measure
physical variables such as pressure,
flow and motion, it is necessary to
use transducers (sensors), which
convert physical variables into
electrical signals and transmit these
signals either to a signal
conditioning device or directly to the
data acquisition board.
Balkan-Data Acquisition 7
The signal conditioning device
performs the following main
functions:
Supplies power to the transducer,
(cid:122)
when required,
Amplifies, filters or digitizes the
(cid:122)
sensor signal,
Provides appropriate output signal
(cid:122)
which is easy to capture with an
analog input board.
Balkan-Data Acquisition 8
Signal conditioners frequently
perform additional functions such
as
bridge balancing,
(cid:122)
integration,
(cid:122)
output calibration,
(cid:122)
overload detection,
(cid:122)
signal level monitoring.
(cid:122)
Balkan-Data Acquisition 9
Signal conditioners must
(cid:122)
perform these functions over the
amplitude and frequency range
of the expected input signal.
Signal conditioners have a large
(cid:122)
effect on measurement system
performance characteristics.
Balkan-Data Acquisition 10