PC-based Data Acquisition selection.

Selecting the right PC-based data acquisition system
to perform mechanical testing is a complex challenge.

A basic understanding of the types of
systems available goes a long way
towards clearing up the confusion
before committing to a specific type of
data acquisition system, it must include
the necessary signal conditioning for
the application.

For example, plug-in board and PC-card systems
typically read only voltages. To measure temperature,
strain and vibration, additional external signal conditioning
hardware would be required to convert the transducers
output to a voltage suitable for the data acquisition
systems input.

Suppliers work closely with systems integrators,
specialists in finding solutions to the customers hardware
and software applications. Choosing the right system
depends on the particular needs of the application.

The very first thing to consider is whether the application
is portable, requiring a notebook PC, or whether a desktop
PC can be used.

Plug-in boards
Data acquisition plug-in boards are a popular solution for
desktop test applications. One advantage is high
acquisition speeds because of direct data-bus connections.
Boards with sampling speeds of up to 200kHz are commonly

On-board processing has the advantage of speeding up
the data analysis by processing the raw data prior to
transferring it to the PC.

PC-card systems
Because of their compact size, most portable PCs cannot
accept plug-in boards. For PCs with a PC-card (PCMCIA)
slot, PC-card data acquisition systems are available.
Although they are more convenient to install than plug-in
boards, PC-cards generally have a more limited capability
due to their small form factor.

However, for many portable applications where the size
of the system is of prime importance they are an ideal
solution. In most cases the PC card can be connected
to signal conditioning modules in a similar fashion to
the plug-in boards.

Externally connected
Where channel expansion, convenient connections, a
quiet environment and signal conditioning are required,
externally connected data acquisition systems may be
a better solution.

These systems make use of the PC's existing ports for
communication, such as the serial port, parallel port,
or the USB (Universal Serial Bus) port. Because they
are external to the PC, external data acquisition systems
offer a number of advantages...

They can be installed without opening the desk-top PC,

They can be easily used with notebook PCs,

They have room for built-in signal connections

They can be easily expanded by adding modules or
boards that contain signal conditioning hardware.

Some external systems can achieve sampling rates up
to 1MHz, making them suitable for dynamic signal
measurement. However, speed is not always of
importance in data acquisition.

USB-based systems are best suited to medium-speed
acquisition and offer true plug-and-play, hot-swapping

Other PC-based data acquisition systems are also
available for measuring slow-changing phenomena
such as temperature and voltage.


For details of Data Acquisition Suppliers, click here...

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