Everyone's excited about USB data acquisition these days as
it's so easy to connect up. But if you're part of a company network,
there's another way that's just as easy, offers more flexibility
and doesn't force you to keep your PC in the same room as your
measuring device: Ethernet data acquisition.
Connecting your data source to your PC via an Ethernet-based data
acquisition system is simply a matter of plugging in standard Ethernet
cabling. Doing so is as easy as using USB; the cabling is inexpensive
and there's probably plenty of it around in your organisation.
By their very nature, Ethernet cables protect the integrity of
your data by reducing the noise that tends to occur when analogue
signals are transmitted over long sensor wires. With Ethernet cabling,
it's feasible to take measurements from signal sources located
30m or more away from the PC.
With an Ethernet-based system, you can just as easily integrate
data acquisition applications into your corporate network. With
a USB connection (or indeed a PCI, parallel or RS232 device) you're
looking at a local set-up - your sensors need to be within a few
feet of your PC. If your organisation already has an Ethernet installation
(and most do these days), you can acquire data in one location
and feed it to PCs located just about anywhere else on the network.
So you don't have to dedicate a PC to data acquisition in every
location where you want to acquire data - and you can monitor and
control the signals on any networked PC that has the appropriate
software installed.
Several companies now produce data acquisition units to accommodate
Ethernet data transfer. One device we particularly like is the
new DataShuttle/2000L from Adept Scientific (http://datashuttle.adeptscience.co.uk)
which connects to your network via a fast 10/100BaseT Ethernet
interface. Like the USB and parallel port DataShuttles, the 2000L
has built-in provision for signal conditioning, which is a great
time-saver and makes it much simpler to set up and run your application.
As a data I/O device, the DataShuttle/2000L is a pretty well-specified
unit. It has built-in capability to measure voltage, frequency
and digital I/O, and it has two internal expansion slots, so you
can easily expand it to measure temperature, strain, vibration
and more. It supports the major software packages, including DASYLab,
LabVIEW and MATLAB, as well as Visual Basic, C/C++ and ActiveX/COM
routines and applications.
If you happen to use the PXI platform for your data acquisition
needs, you can take advantage of National Instruments' (www.ni.com/uk)
Gigabit Ethernet (PXI-8231) or combination Gigabit Ethernet and
GPIB controller (PXI-8232) modules to connect your system directly
to your company's network for the fast transfer of files or video
clips.
Fully compatible with existing Ethernet standards and cabling,
the module's port automatically switches between 10, 100 and 1,000
Mbit/s modes, depending upon network capability. Moreover, it auto-detects
whether the Ethernet cable is a straight-through or crossover type,
allowing either to be used. The PXI boards support NI's LabVIEW,
LabWindows/CVI, Measurement Studio, TestStand and Switch Executive
software suites, and are shipped with NI-488.2 and NI-VISA application
programming interfaces.
Do you have any questions about engineering software that you'd
like to ask Dr Know? He'll be devoting his column in a forthcoming
issue to readers' questions, so if you'd like to submit one of
your own, please contact editor, Les Hunt (les.hunt@imlgroup.co.uk),
who will pass it on.
Dr Know's recommended download is the Datashuttle 2000/L Series Guide - download yours today.