The Newsletter for PC-Based Data Acquisition and Control
Issue 110 www.windmill.co.uk September 2007
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month guide to the different types of wireless networks
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* Windmill News: People counting help
* Logging data wirelessly
* Excel Corner: Adding several y axes to a chart
* DAQ News Roundup
Windmill News: People Counting Help
You can now download the latest Help file for our people
counting software. Called VT Setup, the software
improves the accuracy of counting people into and out of
buildings. It lets you tailor the system to suit each
individual doorway and can handle hundreds of entrances.
To download the new Help file go to
You need to unzip the files before you can use them. In
Windows double-click the vtsetup.zip file and from the
File menu choose Extract All.
For more on counting people see
Logging data wirelessly
Monitoring instruments and sensors wirelessly is
becoming more and more common. A wireless network
saves cabling costs and installation time. It is
useful in electrically noisy or hostile environments.
It lets you move your measuring device from place to
place and remotely monitor conditions. You can log
data from your existing devices wirelessly by adding
appropriate adaptors or routers.
There are several different methods of wireless
communication. The standards for many of these
methods are still being developed.
Bluetooth was designed as replacement for short-range
cables. It allows up to seven devices to be monitored
over short distances, typically about 10 meters. It is
called a wireless Personal Area Network (PAN) and
conforms to the IEEE 802.15 standard. It is suitable
when devices are close to the computer and high
bandwidth is not required. You can use Bluetooth to
log data from RS232 instruments by plugging a
Bluetooth radio adaptor into your PC's COM port and
one into your instrument. You can then use software
like Windmill's COMIML to collect data
Bluetooth is named after a Danish king who unified
Denmark and Norway.
Further reading: http://www.bluetooth.com/
Wibree (Ultra Low Power (ULP) Bluetooth)
Wibree is a new interoperable radio technology for
small devices like sports sensors. It was designed
by Nokia for applications where ultra low power
consumption, small size and low cost were the critical
requirements. In June this year it was decided that
Wibree would be included in the Bluetooth
specifications and renamed Ultra Low Power (ULP)
Bluetooth. Further reading: http://www.wibree.com/
Similar to a traditional Ethernet model, WiFi comprises
a local area network (LAN). It uses the same radio
frequency as Bluetooth, but with higher power consumption.
WiFi is preferable to Bluetooth for operating medium-to-
large networks because it allows for a faster connection
speed, greater range, more devices to be monitored and
higher security levels. For more on WiFi and data
acquisition see Issue 82 of Monitor,
ZigBee was designed specifically for remote monitoring
and control. It comprises a personal area network based
on the IEEE 8-2.15.4 standard. ZigBee can support
thousands of nodes in a star or mesh network. In a star
network all devices communicate with the controlling node,
as is used by WiFi and Bluetooth. In a mesh network,
messages can be passed from node to node such that if any
of the nodes fail, the message can still reach the
destination. Once associated with a network, a ZigBee
node can wake up and communicate with other ZigBee
devices then return to sleep. This and its low power
means that a device's battery can last a very long time.
Further reading: http://www.zigbee.org/
Passed earlier this month, the HART 7 specification
includes the wireless protocol dubbed WirelessHART.
This sets out to create a wireless version of the
Wired HART protocol in order to ensure backward
compatibility with wired devices. HART Communication
is used to communicate between intelligent field
instruments and host systems.
Further reading: http://www.hartcomm.org/
WiMax, the Worldwide Interoperability for Microwave
Access, aims to provide wireless data over long
distances in a variety of ways. It is based on the
IEEE 802.16 standard, which is also called WirelessMAN.
Typically it has a range with a radius of 3 to 10 km.
The WiMAX Forum expects the technology to allow city-
wide wireless broadband access. In the data acquisition
field, WiMax is envisaged as most useful for monitoring
Further reading: http://www.wimaxforum.org/
GPRS and GSM
GSM (2G) networks are used for voice calls from mobile
(cell) phones. They are limited when it comes to sending
or receiving data as it can take up to 30 seconds to
make a connection to the network. GPRS is a method of
enhancing GSM. GPRS (General Packet Radio Service)
devices can transfer data immediately and at higher
speeds. GPRS uses the existing GSM network to transmit
and receive TCP/IP based data to and from GPRS mobile
devices. GPRS devices are always on, as opposed to
dial-up modems. You can connect Ethernet devices to
a GPRS network by adding a suitable GPRS router.
More Wireless Resources:
IEEE Wireless Standards Zone
The IEEE is developing open, consensus standards for
The ISA-SP100 group formed in 2004 with the charter to
establish standards and recommended practices for
implementing wireless systems in the automation and
control environment, with a focus on the field level.
ISA: Users fear wireless networks for control
Excel Corner: Adding several y axes to a chart
We were asked this month how to plot 3 variables on an
Excel chart, each with a different y axis. Excel doesn't
offer an option to do this, but there are work-arounds
to achieve it.
On way relies on using a dummy chart series to add a
third axis. This was pioneered by Jon Peltier. He
describes the method at
The second method is to display traces separately,
like the Windmill Chart program does
This is also known as a panel chart, a trellis chart,
a stacked line chart or a multi-plot chart. Details of
how to achieve this in Excel are given at
Jon Peltier's site at
For more on data acquisition and control using Excel see
DAQ News Roundup
Welcome to our roundup of the data acquisition and
control news. If you would like to receive more
timely DAQ news updates then grab our RSS newsfeed
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http://www.windmill.co.uk/newsfeed.php for notes
on how to display the news on your own web site,
read it via e-mail, mobile phone or a newsfeed viewer.
Ear-sensor helps athletes
A new body sensor, the size of a hearing aid,
monitors the performance of an athlete while training.
The sensor fits behind the ear and gathers data about
posture, stride length, acceleration and response to
shock waves travelling through the body. A computer
inside the earpiece and transmits data to a laptop
for real-time monitoring of athletic performance.
Source: Imperial College
NIST measures challenges for wireless in factories
Heavy industrial plants are challenging
environments for wireless systems. They can be
highly reflective, scattering radio waves
erratically, and interfering with or blocking
wireless transmissions. NIST have identified a
number of steps to take minimise radio interference
on the factory floor.
Source: National Institute of Standards and Technology
Smart homes could track your electrical noise
Your computer could one day track your movements
around the house by monitoring the electrical noise
made by household appliances as you switch them on
and off. Such a system could be cheaper and simpler
to operate than the suite of sensors that researchers
currently envisage for "smart homes".
Source: New Scientist
Beyond Batteries: Storing Power in a Sheet of Paper
Researchers at Rensselaer Polytechnic Institute,
New York, have developed a new energy storage
device that easily could be mistaken for a simple
sheet of black paper. The battery is lightweight,
ultra thin, completely flexible, and geared toward
meeting the trickiest design and energy requirements
of tomorrow's devices.
Source: Rensselaer Polytechnic Institute
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