31
June 2014
I
NTERNET
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OF
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HINGS
Originally launched by Nokia as Wibree in
2006, Bluetooth Low-Energy (BLE) or Bluetooth
Smart provides a similar range to classic Blue-
tooth but with reduced power consumption.
In place of the 1MHz channels used by the
original Bluetooth protocol, BLE uses a smaller
set of wider-bandwidth channels of 2MHz but
with a lower peak data rate. The channel band-
width is similar to that of ZigBee but with nar-
rower spacing. A key advantage of BLE is its
lower latency, just 3ms versus the 100ms of
classic Bluetooth, as well as lower complexity,
so that its software stack can easily be incorpo-
rated into lower-cost microcontrollers. BLE re-
tains support for frequency hopping from the
original Bluetooth protocol, which makes it
more robust than ZigBee in the presence of
strong interfering signals. One of the main ap-
plication areas for BLE is medical instrumenta-
tion, where a number of on-body sensors to
monitor heart rate, blood pressure, and posture
relay their readings at regular intervals to a
central controller, which may be a mobile
phone or a dedicated medical instrument.
Having been in use in various forms for more
than 15 years, Wi-Fi has the benefit of being
the most mature wireless-networking radio
technology suitable for IoT applications.
Through protocols such as WPS, Wi-Fi can
offer easy integration into an existing network
for devices that have little to no physical user
interface. Of the wireless technologies suitable
for IoT applications, Wi-Fi has the best power-
per-bit transmission efficiency. Conventional
Wi-Fi designs tend to use more energy to
maintain a connection while quiescent than
protocols such as BLE, which can decrease en-
ergy efficiency if the application does not need
high bandwidth. However, vendors such as
GainSpan have worked on power efficiency in
designs such as the GS2000, which combines
support for both ZigBee and Wi-Fi on the
2.4GHz and 5GHz band. These designs put
the radio into an energy-saving standby mode
if the sensor node does not need to transmit
any data. It wakes up only to send data or
keep alive connection packets used to assure
central controllers that the node has not failed.
In general, Wi-Fi tends to suit applications
where compliance with the IP stack is an ad-
vantage, there is a requirement to deliver large
amounts of data, such as audio or video, or
the remote devices can be powered by external
energy sources. An example of Wi-Fi in use is
by Mernok Elektronik of South Africa, which
used modules from connectBlue to incorporate
wireless networking into the locomotive control
and safety management systems of railway
systems used in mining. The modules are used
to collect real-time operation data on each ve-
hicle and provide a robust wireless connection
across both 2.4GHz and 5GHz frequency bands
with support for over-the-air firmware updates
and parameter changes.
BLE andWi-Fi can be used together efficiently
as they both support coexistence protocols de-
signed to reduce interference between the two
on their common frequency band of 2.4GHz.
This coexistence ability lends itself to imple-
mentation in gateway designs where BLE is
used for connections to sensor nodes and Wi-
Fi for relaying aggregated data to a backbone
network. The APx4 from Bluegiga provides an
off-the-shelf solution for this, providing sup-
port for both Wi-Fi and the full Bluetooth 4.0
software stack that includes BLE, based around
a powerful 450MHz ARM9 processor. A num-
ber of integrated microcontrollers and support
chipsets from vendors such as Atmel, CSR,
Freescale, STMicroelectronics and Texas In-
struments provide support for protocols such
as BLE,Wi-Fi and ZigBee. For implementations
that need flexibility, the configurable radio
transceivers made by Lime Microsystems make
it easier to deploy nodes that can be pro-
grammed with a specific RF interface person-
ality at the point of manufacture to suit different
networking needs in the target system.
Figure 2. Channel arrangements for ZigBee,
BluetoothLE and Wi-Fi
Innovasic: RapID platform for PROFINET IRT
Innovasic has certified the solution for both Class B and Class C. Now it is possible to design in
PROFINET with the RapID Platform and take advantage of seamless support for version v2.3.
Innovasic’s solution allows users to certify their design to v2.3 through any of the PI Test
Labs. The PROFINET IRT network interface is delivered as a module or embedded design con-
taining everything needed to participate in a PROFINET IRT and RT network. A host processor
connects to the Network Interface via a UART or 16-bit Parallel Interface.
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