Remote control of CANbased industrial equipment using Internet technologies

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Remote control of CAN-based industrial equipment
usingInternet technologies

• Prof. Dr.-Ing. Gerhard Gruhler, University of
  Applied Sciences Reutlingen,
• Steinbeis Technology Transfer Center Automation
  (STA), Germany

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For demonstration purposes the described systems
are online 7 days / 24 hours andcan be accessed
by everyone from all over the world.
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CAN is not only used to great extent in carsand
other mobile applications but also inindustrial
equipment, machine control,building control,
medical and other devices inthe service/public
area. Due to the globalmarket place, in most
these fields remotesystem access becomes more
and moreimportant.
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ISO 11898 defines the Physical Layer.

• The CAN bus CANbus is a Balanced (differential)
  2-wire interface running over either a Shielded
  Twisted Pair (STP), Un-shielded Twisted Pair
  (UTP), or Ribbon cable. Each node uses a Male
  9-pin D connector. The Bit Encoding used is Non
  Return to Zero (NRZ) encoding (with bit-stuffing)
  for data communication on a differential two wire
  bus

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A number of different data rates are defined,
with 1Mbps (Bits per second) being the top end,
and 10kbps the minimum rate. All modules must
support 20kbps. Cable length depends on the data
rate used. Normally all the devices in a system
transfer uniform and fixed bit-rates. The maximum
line length is 1Km, 40 meters at 1Mbps.
Termination resistors are used at each end of the
cable. The worst-case transmission time of an
8-byte frame with an 11-bit identifier is 134 bit
times (that's 134 microseconds at the maximum
baud rate of 1Mbits/sec).
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AdvantagesThese are e.g.- more reliable
communication channels,- use of PC-based
standard technologiesand software like
TCP/IP-stack, webservers, browsers, Java, XML
etc.- significant cost reduction
fordevelopment, equipment and operation- less
effort in particular on the clientsside
usually the client just needs astandard web
browser,- worldwide availability of internet
accessat low costs
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The range of possible remote accessapplications
and the related benefit is large- remote
production and machine datacollection,- remote
system monitoring,- remote error detection,-
remote observation purposes, also forsecurity
reasons,- customer support for programming
andrunning the system, help for bug fixing,-
remote device parameterisation,-
software/firmware updates via internet,- better
support for maintenance staff,- sometimes even
avoiding service trips,
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direct system control by remoteoperator
interface,- and last but not least better
marketingsupport some device manufacturers
notonly provide the usual bunch ofdocumentation
on their web-site but startto make accessible
real devices fordemonstration purposes to
theirperspective customers.
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High-level web interfaces
High-level remote access to a KUKA robot via
internet and CAN
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High-level web interfaces
High-level remote programming and control concept
for a FESTO handling robot using CAN
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Remote access to and monitoring of lower CAN
layers
CAN Message Manager's web interface
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Remote access to and monitoring of lower CAN
layers
Concept of extending CAN systems over the
internet using CAN-TCP/IP-CAN gateways
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Remote access to and monitoring of lower CAN
layers
Software structure of CAN-TCP/IPCAN gateways
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PC-based and embedded systems for webserver and
client
Examples of embedded web servers, partially
available with CAN interface
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PC-based and embedded systems for webserver and
client
Remote access concept, not capable of passing
firewalls.
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PC-based and embedded systems for webserver and
client
Modified access method, to overcome firewalls