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Virtual Automation Networks 15-3<br />

GSDML<br />

PROFINET<br />

engineering<br />

Controller<br />

IO device<br />

PROFINET<br />

Linking<br />

device<br />

IO<br />

proxy<br />

FB<br />

master<br />

IO device<br />

IO<br />

proxy<br />

PB<br />

master<br />

Linking<br />

device<br />

FB slave<br />

PROFIBUS<br />

slave<br />

FB slave<br />

PROFIBUS<br />

slave<br />

FB slave<br />

PROFIBUS<br />

slave<br />

FB slave<br />

PROFIBUS<br />

slave<br />

Fieldbus<br />

PROFIBUS DP<br />

FIGURE 15.2 Integration of fieldbus <strong>systems</strong> by PROFINET (IO, input/output; FB, fieldbus; PB, PROFIBUS; DP,<br />

decentral periphery).<br />

A heterogeneous network has to handle different classes of application data (application classes):<br />

• Decentralized periphery applications<br />

• Real-time applications/control loops (networked control)<br />

• Component-based applications<br />

• Telecontrol (TC) applications<br />

• Teleservices<br />

For these application classes, different requirements and opportunities exist. Limitations are,<br />

e.g., regarding isochronous and hard real-time <strong>communication</strong> caused by the performance of heterogeneous<br />

networks. The next sections give an introduction into the problems to be solved and<br />

into the developed concept. The main idea is to connect the local <strong>industrial</strong> <strong>communication</strong> <strong>systems</strong><br />

(e.g., PROFINET as automation backbone connected with different fieldbus <strong>systems</strong> following<br />

the mentioned integration concept) via tunnel through the heterogeneous WAN with one or more<br />

remote <strong>industrial</strong> <strong>communication</strong> system.<br />

15.2 Virtual Automation Network: Basics<br />

In a geographically distributed automation project, various local and remote installations based on<br />

fieldbus <strong>communication</strong>, connected by a heterogeneous WAN, exist. In virtual automation networks<br />

(VANs), the distributed automation function (local and remote parts) forms a domain (Figure 15.3),<br />

containing all installed equipment to realize these automation functions. Thus, a VAN domain covers<br />

all devices that shall be grouped together on a logical or virtual basis to represent a complex application.<br />

Depending on the complexity of the automation function, a hierarchical domain approach makes sense.<br />

It means that there are also domains and subdomains that can consist of subdomains, etc. Consequently,<br />

© <strong>2011</strong> by Taylor and Francis Group, LLC

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