|
|
| Date Posted:
5/15/2008 4:13:12 AM
Status:
Live |
|
|
Asker's Rating:
Not Helpful
|
|
Response:
Data acquisition systems, as the name implies, are products and/or processes
used to collect information to document or analyze some phenomenon. In the
simplest form, a technician logging the temperature of an oven on a piece of
paper is performing data acquisition. As technology has progressed, this type of
process has been simplified and made more accurate, versatile, and reliable
through electronic equipment. Equipment ranges from simple recorders to
sophisticated computer systems. Data acquisition products serve as a focal point
in a system, tying together a wide variety of products, such as sensors that
indicate temperature, flow, level, or pressure. Some common data acquistion
terms are shown below:
- Analog-to-digital converter (ADC)
An electronic device that
converts analog signals to an equivalent digital form. The analog-to-digital
converter is the heart of most data acquisition systems.
- Digital-to-Analog Converter (D/A)
An electronic component found in
many data acquistion devices that produce an analog output signal.
- Digital Input/Output (DIO)
Refers to a type of data acquistion
signal. Digital I/O are discrete signals which are either one of two states.
These states may be on/off, high/low, 1/0, etc. Digital I/O are also referred to
as binary I/O.
- Differential Input
Refers to the way a signal is wired to a data
acquisition device. Differential inputs have a unique high and unique low
connection for each channel. Data acquisition devices have either single-ended
or differential inputs, many devices support both configurations.
- General Purpose Interface Bus (GPIB)
Synonymous with HPIB (for
Hewlett-Packard), the standard bus used for controlling electronic instruments
with a computer. Also called IEEE 488 in reference to defining ANSI/IEEE
standards.
- Resolution
The smallest signal increment that can be detected by
a data acquisition system. Resolution can be expressed in bits, in proportions,
or in percent of full scale. For example, a system has 12-bit resolution, one
part in 4,096 resolution, and 0.0244 percent of full scale.
- RS232
A standard for serial communications found in many data
acquistion systems. RS232 is the most common serial communication, however, it
is somewhat limited in that it only supports communication to one device
connected to the bus at a time and it only supports transmission distances up to
50 feet.
- RS485
A standard for serial communications found in many data
acquistion systems. RS485 is not as popular as RS232, however, it is more
flexible in that it supports communication to more than one device on the bus at
a time and supports transmission distances of approximately 5,000 feet.
- Sample Rate
The speed at which a data acquisition system collects
data. The speed is normally expressed in samples per second. For multi-channel
data acquisition devices the sample rate is typically given as the speed of the
analog-to-digital converter(A/D). To obtain individual channel sample rate, you
need to divide the speed of the A/D by the number of channels being
sampled.
- Single-ended Input (SE):
Refers to the way a signal is wired to a
data acquisition device. In single-ended wiring, each analog input has a unique
high connection but all channels share a common ground connection. Data
acquisition devices have either single-ended or differential inputs. Many
support both configurations.
|
|
|
|
If you post one question/problem, I will provide 1 input/answer. If you put "x" questions/problems, I will provide"x" inputs/answers. In both cases, appropriate ratings are appreciated for every input. Thanks.
|
|
|