Page 282 - Electric Drives and Electromechanical Systems

Chapter 11 Cyber Physical systems and security 279

Table 11.1 Industrial networking standards that are current
or present in legacy systems.
Application Product
Enterprise bus Ethernet
Control bus HSE, ControlNet
Field bus Foundation Fieldbus, Profibus PA,
Device bus DeviceNet, Profibus Dp, Interbus-S
Sensor bus CAN, ASI, Seriplex, LANWorks

Several standards developed by system manufactures have evolved and can be found
in legacy or current applications, these include:

DeviceNet (2005) is a digital, multi-drop network that is capable of operating
between industrial controllers and I/O devices, and is considered to be the de facto
standard in the US semiconductor industry. In the DeviceNet architecture each
device and/or controller is considered to be a node on the network. One of the
important features of this technology is that power is provided on the network.
This allows devices with limited power requirements to be powered directly from
the network, reducing connection points, physical size and cost. DeviceNet
conforms to the OSI model, and as such is an open standard. DeviceNet uses
Controller Area Network or CAN for its communication layer. The CAN protocol is
defined by ISO 11898-1 and comprises the data link layer of the seven-layer ISO/
OSI reference model. CAN provides two communication services, either the
sending of a message or the requesting of a message (Remote Transmission
Request, RTR). The CAN approach is capable of providing, a multi-master hierar-
chy, which permits the development of intelligent and redundant systems. An
important feature is that if one network node fails the network is still able to
operate.
PROFIBUS (2005) or the Process Field Bus is based on the IEC 61158 standard and
is mainly used at field level with capabilities to operate down to the sensors, or up
to the production levels. A number of variants have been designed for factory
operation (PROFIBUS DP), motion control (PROFIdrive), process operation
(PROFIBUS PA) or safety applications (PROFIsafe). In PROFIBUS DP and
PROFIdrive the communication is based on RS485, and has the capability of speed
up to 31.25 Kbps up to distances of 1900 m, and uses a logical token ring with a
master/slave paradigm. In using PROFIBUS a drive system can be controlled
remotely, for example setting speeds; the actual closed loop speed control is
carried out by the drive itself. The electronic line shaft application shown in
Fig. 10.11 is a typical application where the synchronising features of the
PROFIdrive system can be used. Instead of the drives being hardwired, each drive