Selecting the Right Data Acquisition System
Engineers often must monitor a handful of signals over extended periods of time, and then
graph and analyze the resulting data. The need to monitor, record and analyze data arises in
a wide range of applications, including the design-verification stage of product development,
environmental chamber monitoring, component inspection, benchtop testing and process
trouble-shooting.
This application note describes the various methods and devices you can use to acquire,
record and analyze data, from the simple pen-and-paper method to using today's
sophisticated data acquisition systems. It discusses the advantages and disadvantages of
each method and provides a list of questions that will guide you in selecting the approach that
best suits your needs.
Introduction
In geotechnical engineering, we sometime encounter some difficulties such as monitoring
instruments distributed in a large area, dangerous environment of working site that cause
some difficulty for easy access. In this case, operators may adopt remote control, by which a
large amount of measured data will be transmitted to a observation room where the data are
to be collected, stored and processed.
The automatic data acquisition control system is able to complete the tasks as regular
automatic data monitoring, acquisition and store, featuring high automation, large data store
capacity and reliable performance.
The system is composed of acquisition control system and display system, with the following
features:
1. No. of Channels: 32 ( can be increased or decreased according to user's real needs.)
2. Scanning duration: decided by user, fastest 32 points/second
3. Store capacity: 20G( may be increased or decreased)
4. Display: (a) Table of parameter (b) History tendency (c) Column graphics.
5. Function: real time monitoring control, warning
6. Overall dimension: 50cm×50cm×72cm
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:
Data acquisition technology has taken giant leaps forward over the last 30 to 40 years. For
example, 40 years ago, in a typical college lab, apparatus for tracking the temperature rise in
a crucible of sodiumtungsten- bronze consisted of a thermocouple, a bridge, a lookup table, a
pad of paper and a pencil.
Today's college students are much more likely to use an automated process and analyze the
data on a PC Today, numerous options are available for gathering data. The optimal choice
depends on several factors, including the complexity of the task, the speed and accuracy you
require, and the documentation you want. Data acquisition systems range from the simple to
the complex, with a range of performance and functionality.
Pencil and paper
The old pencil and paper approach is still viable for some situations, and it is inexpensive,
readily available, quick and easy to get started. All you need to do is hook up a digital
multimeter (DMM) and begin recording data by hand.
Unfortunately, this method is error-prone, tends to be slow and requires extensive manual
analysis. In addition, it works only for a single channel of data; while you can use multiple
DMMs, the system will quickly becomes bulky and awkward. Accuracy is dependent on the
transcriber's level of fastidiousness and you may need to scale input manually. For example,
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