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wilamowski-b-m-irwin-j-d-industrial-communication-systems-2011

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50-4 Industrial Communication Systems<br />

Application framework<br />

Application (APL) layer<br />

ZigBee<br />

Security<br />

service<br />

provider<br />

(End<br />

manufacturer<br />

defined)<br />

Application<br />

object 240<br />

Endpoint 240<br />

APSDE-SAP<br />

APS security<br />

management<br />

NLDE-SAP<br />

Security<br />

management<br />

. . .<br />

Message<br />

broker<br />

(End<br />

manufacturer<br />

defined)<br />

Application<br />

object 1<br />

Endpoint 1<br />

APSDE-SAP<br />

Application support sublayer (APS)<br />

APS message<br />

broker<br />

Network (NWK) layer<br />

ZDO public<br />

interfaces<br />

Routing<br />

management<br />

Zigbee device object<br />

(ZDO)<br />

Endpoint 0<br />

APSDE-SAP<br />

Reflector<br />

management<br />

NLME-SAP<br />

Network<br />

management<br />

APSME-<br />

SAP<br />

NLME-<br />

SAP<br />

ZDO Management<br />

plane<br />

MLDE-SAP<br />

MLME-SAP<br />

IEEE 802.15.4<br />

PD-SAP<br />

Medium access control (MAC) layer<br />

PLME-SAP<br />

2.4 GHz radio Physical (PHY) layer 868/915 MHz radio<br />

FIGURE 50.3<br />

ZigBee stack.<br />

• Contention-based channel access, CSMA/CA<br />

• Message transmission can be fully acknowledged<br />

• Beacon from 15.ms up to 4.min, allowing very low duty cycles.<br />

• Optional guaranteed time slots (GTSs) can be reserved<br />

• 16 bit address field or extended 64 bit addresses<br />

• Link quality indication byte is attached to each receiver<br />

50.5.1 Physical Layer<br />

There are two groups of frequency bands specified: 2.45.GHz and 868/915.MHz. The popularity<br />

of 2.45.GHz is very high compared to the 868/915.MHz solutions that require different hardware and<br />

cannot just be switched by software (Figure 50.4).<br />

Channel 0 Channels 1–10<br />

915 MHz<br />

2 MHz<br />

868.3 MHz<br />

902 MHz<br />

928 MHz<br />

Kanal 11–26<br />

5 MHz<br />

2.4 GHz<br />

2.45 GHz 2.4835 GHz<br />

FIGURE 50.4<br />

Frequency spectrum.<br />

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

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