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Virtual Automation Networks 15-5<br />

15.2.2 Components<br />

There are two groups of VAN components [NPM08,SOP06]:<br />

• VAN infrastructure components: VAN access point (VAN-AP), VAN gateway (VAN-GW), VAN<br />

server device (VAN-SVD), VAN security infrastructure device (VAN-SID), VAN engineering<br />

station.<br />

• Automation-specific VAN components: VAN automation device (VAN-AD), VAN-PD, VAN virtual<br />

device (VAN-VD).<br />

The infrastructure components enable the establishment and maintenance of the tunnel between distributed<br />

application objects (runtime objects). The automation-specific components are VAN-enabled ADs.<br />

A VAN-AP, the most important infrastructure component, connects VAN network segments. It does<br />

not contain an automation function or an automation application process. It can work as a gateway or<br />

a router to ADs that are members in a VAN application context (VAN domain). Thus, a VAN-AP may<br />

handle different transmission technologies, contains all relevant administration functions (necessary<br />

for configuration and parameter setting in connected subnetworks). It enables the switching between<br />

available <strong>communication</strong> paths and finds the best transmission technology and the best route through<br />

the different subnetworks of the heterogeneous network.<br />

Within a VAN domain, there are different opportunities how any AD can participate in a VAN network<br />

(Figure 15.4):<br />

• By integrating the VAN <strong>communication</strong> capabilities at the AD itself (VAN-AD)<br />

• By connecting a single device via a separate VAN gateway device<br />

• By connecting the whole network segment (e.g., connecting the ADs using any <strong>industrial</strong> <strong>communication</strong><br />

system/fieldbus) through a VAN-PD and mapping its application objects to the VAN<br />

object pool that its parts (VAN-VD) can be exchanged within the VAN domain<br />

VAN<br />

VAN network<br />

capability<br />

Automation<br />

function<br />

VAN-AD<br />

VAN<br />

VAN network<br />

capability<br />

VAN-PD<br />

FD1<br />

FD2<br />

FD5<br />

VAN-VDs<br />

Industrial comm.<br />

capability<br />

FD2<br />

Fieldbus<br />

network with<br />

several devices<br />

FD1<br />

FD4<br />

FD1, 2, 5 are VAN-virtual devices (VAN aware)<br />

FD3, 4 are not visible in VAN (VAN independent)<br />

FD5<br />

FD3<br />

Automation<br />

function<br />

FIGURE 15.4 Automation-specific components (AD, automation device; PD, proxy device; VD, virtual device;<br />

FD, field device).<br />

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

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