HL3.DEC–IOtech–wy
Data acquisition module expands notebook PC I/O capability
Module performs equally well in portable as well as desktop applications
DaqBook/100, an add-on module the size of a notebook PC, provides
multifunction I/O capabilities to the notebook PC for portable-test and
data-acquisition applications. The module measures 8 1/2 x 11 x 1 3/8 in.
and fits under a typical notebook PC. It is powered by a 12-V car battery,
an ac adapter, or an optional nickel-cadmium battery. DaqBook/100
provides 16 analog inputs, expandable to 256 inputs with optional add-on
modules for multiplexing a variety of transducers. It attaches directly to
a PC's parallel port (see box) and transfers data bidirectionally at up to
170 Kbytes/s, permitting real-time acquired data to be stored in the PC's
memory and on the PC's hard-disk drive. Furthermore, because the
DaqBook/100 connects to the PC's parallel port, it provides another
parallel port for connecting a parallel printer to the PC. DaqBook/100
goes a long way toward overcoming the limitations of the notebook PCs that
offer expansion slots. These notebooks can run for 6 hours or more on a
single battery charge and are therefore increasingly being considered for
portable and remote data-acquisition applications. However, these
computers' handicaps until now have been increased size, shorter battery
life, inability to accept full-length plug-in data acquisition boards, and
higher cost. DaqBook/100 provides a wide variety of data acquisition
capabilities. These include a 100-kHz, 12-bit, 16-channel A/D converter with
a programmable-gain input amplifier; two 12-bit D/A converters; five
16-bit counter-timers; 16 digital inputs that can be sampled at up to 100
kHz; and 24 general-purpose digital I/O lines. The A/D converter performs
100-kHz scan sequences and provides programmable delays of from 10
microsecond to 10 hours between each sequence. A 512-location scan
sequencer allows users to select each analog channel and associated input
amplifier gain at random; by contrast, similar plug-in boards typically
allow users to select only the first and last channel of a sequence.
DaqBook/100 scans all of its analog input channels at 100 kHz, including
the up to 256 expansion channels; similar plug-in data acquisition boards
typically scan expansion-channel signals at only 4 kHz. DaqBook/100 also
allows users to scan 16 digital inputs in the same scan sequence employed
for analog inputs, enabling acquired digital data to be time-correlated to
acquired analog data. DaqBook/100 comes with DOS and Windows software
drivers, as well as a graphical Microsoft Windows application that allows
users to save data acquired from an application directly to disk or to
seamlessly transmit the data to other Windows applications, such as
spreadsheets and databases. An optional nickel-cadmium battery supply
provides up to 10 hours of operation. Optional modules include: a screw
terminal signal-connection module, a 16-channel analog multiplexer module,
an eight-channel thermocouple module, a four-channel strain-gauge module, a
four-channel anti-aliasing filter module, and a four-channel simultaneous
sample-and-hold module. ($1,295–8 weeks ARO.) IOtech, Inc., Cleveland,
OH Tom DeSantis 216-439-4091 Fax 216-439-4093
CAPTION:
DaqBook/100 module provides add-on test and data acquisition capabilities
for notebook PCs.
BOX:
Why the parallel port?
Other ports besides the parallel port are available on most notebook PCs
to provide interface options. But the capabilities of these ports
generally fall short when compared to the parallel port. For example,
serial-port-based hardware for connecting instruments like data loggers
and DMMs has been available on PCs for years. For notebook PCs, however,
instruments like these are too power hungry for portable applications.
Furthermore, the typical 2-Kbyte/s speed obtainable with serial-port-based
hardware falls far short of the speed required for many applications.
Many of the newer notebook PCs have a proprietary expansion connector for
interfacing an external expansion chassis that accepts standard-length PC
plug-in boards. These chassis not only add to the bulk and cost of a
notebook PC, but greatly reduce the life of the PC's battery. A few of
the newest higher-end notebook PCs provide a standardized PCMCIA socket
that accepts credit-card-sized devices like memory boards, network
interfaces, and modems. Although capable of supporting
megabyte-data-transfer rates, the biggest drawback in using the PCMCIA
socket for data acquisition is, besides its relative scarcity right now,
that it will not then be available functions for which it is particularly
well suited, such as hosting an nonvolatile RAM card for storing analog
and digital data.
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