Remote control - CAN bus 1

Remote control of CAN-based industrial equipment using

Internet technologies

Prof. Dr.-Ing. Gerhard Gruhler, University of Applied Sciences Reutlingen,

Steinbeis Technology Transfer Center Automation (STA), Germany

Remote control - CAN bus 2

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 in

the service/public area. Due to the globalmarket place, in most these fields remotesystem access becomes more and more

important.

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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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Advantages:These are e.g.:

- more reliable communication channels,- use of PC-based standard technologies

and software like TCP/IP-stack, webservers, browsers, Java, XML etc.

- significant cost reduction fordevelopment, equipment and operation- less effort in particular on the client´s

side: usually the client just needs astandard web browser,

- worldwide availability of internet accessat low costs

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Remote control - CAN bus 10

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 not

only provide the usual bunch ofdocumentation on their web-site but start

to make accessible real devices fordemonstration purposes to their

perspective 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 web

server and client

Examples of embedded web servers, partially available with CAN interface

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PC-based and embedded systems for web

server and client

Remote access concept, not capable of passing firewalls.

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PC-based and embedded systems for web

server and client

Modified access method, to overcome firewalls