Various ‘real time’ incarnations of the Ethernet
protocol are gaining ground as the industrial networking options
of choice for high-speed industrial automation systems - a subject
covered in some depth by DPA last March. Along with USB, Ethernet
is also fast becoming the network of choice for data acquisition
(DAQ), particularly as it is fast and reliable, simply plugs into
your PC and is often able to make use of existing LANs and network
infrastructures.
Measurement Computing’s (www.measurementcomputing.com) new DAQ device,
the E-PDIS016, which is available in the UK from Adept Scientific
(www.adeptscience.co.uk), is a 10/100Base-T Ethernet digital I/O system that
includes integrated signal conditioning, 16 isolated inputs and
eight electromechanical relay outputs. The inputs monitor 24V ac
or dc, while the relays provide 6A (Form C, SPDT) outputs at 240Vac
or 28Vdc. The hardware is supplied with a suite of software products,
including DasyLab, MatLab’s Data Acquisition Toolbox, plus
library, VIs and program examples for LabVIEW, among others.
Also supported by Adept Scientific is the Datashuttle 2000L series
(http://datashuttle.adeptscience.co.uk/). Both units in the range
come equipped with built-in signal I/O capability for synchronous
measurement of analogue inputs at 16-bit resolution, as well as
frequency and digital inputs. The system can be supplied with signal
conditioning modules that reside within the unit’s rugged
housing, allowing transducers such as ICP accelerometers and strain
gauges to be connected and monitored.
You can connect any RS232 enabled instrument or serial device
directly to an Ethernet network using a Micro Serial Server (MSS1)
unit from Lantronix (www.lantronix.com) and communicate with it
via TAL Technologies (www.taltech.com) TCP-Wedge TCP/IP communications
software. Each Lantronix MSS1 has its own IP address, so TCP-Wedge
can input data from each port directly into spreadsheets, control
software packages, LabVIEW and HMI systems.
LabJack (www.labjack.com) has a combined USB/Ethernet data acquisition
device – the UE9 – that offers 14 analogue inputs,
each of which can be configured individually, with 12-bit and 16-bit
resolutions, depending upon how fast you want it to work. There
are two 0-4.8V analogue outputs and 23 digital I/O channels that
can be individually configured as input, output-high or output-low.
Eight of these can be software configured as up to six timers and
two counters. And if you happen to have an Ethernet switch device
to hand, you can connect many LabJack UE9s to a single PC and set
up a low-cost, low-speed, high channel count application.
Sena (www.sena.com) is another company that has seen the growing
uptake of Ethernet as a viable network technique for process measurement
applications. Its HelloDevice SS110, for example, offers network
connectivity for oil well controller applications using TCP socket
services, allowing them to be connected to all kinds of LAN based
equipment. The unit is equipped with two RJ-45 connectors: one
for RS232/422/485 enabled sensors and the other for Ethernet connectivity.
The SS110 provides access via DSL-based broadband networks as well
as conventional LANs through the 10/100Mbit/s Ethernet interface,
while wireless connectivity is available by plugging an appropriate
device into the SS110’s PCMCIA slot.
Data acquisition and control using Modbus/TCP is a feature of
Advantech’s (www.advantech.com) Adam 6000 series industrial
Ethernet DAQ device. Similar in many ways to other remote data
acquisition modules, this one has the added advantage of embedded
mathematical functions that enhance system performance. These modules
can be used with a very wide range of sensor devices, including
thermocouples (seven types), RTD sensors, pressure flow, voltage
and current, while a special variant also offers PID control algorithms.
Of course, you can get very specialised in the Ethernet based
data acquisitions field. You might be interested in acquiring just
one parameter – pressure or temperature, say – but
from a number of points at very high speed. Researchers in the
aerospace and FI development sectors will be very familiar with
such systems, often referred to as ‘scanners’.
A good example is Pressure Systems’ model 9016 intelligent
pressure scanner, which is available in the UK from Chell Instruments
(www.chell.co.uk). This device comprises 16 silicon piezoresistive
pressure sensors with temperature compensation and, thanks to some
clever internal electronics and software, will deliver an accuracy
of 0.05% full scale. It is capable of making 100 separate pressure
measurements (in engineering units) per channel per second, and
then transmitting this via a 10Mbit Ethernet interface supporting
both TCP and UDP protocols.
Dr
Know's recommended download is Measurement Computing PC-based
Data Acquisition Catalogue - download yours today.