ZFR1800 Series Wireless Field Bus System Technical Bulletin 65
Appendix A: ZigBee Overview
The ZigBee network is a global open networking standard that defines a low-cost,
low-power, two-way wireless communication system. Its development comes from
the ZigBee Alliance, an organization of manufacturers devoted to providing a
cost-effective wireless networking technology for use in commercial and
residential applications. The primary advantages that ZigBee technology brings to
the marketplace include the following:
• high reliability and security
• low power with multi-year battery life
• low complexity at an economic cost
ZigBee Communications Technology
The ZigBee network is a Personal Area Network (PAN) based on the Institute of
Electrical and Electronic Engineers (IEEE) 802.15.4 standard for low power, low
duty-cycle wireless transmitting systems. Devices on the network use Direct
Sequence Spread Spectrum (DSSS) wireless technology and operate on the
2.4 GHz Industrial, Science, Medical (ISM) band.
Devices on the ZigBee network are different from Bluetooth® devices and
wireless Universal System Bus (USB) devices in that they form a mesh network
between nodes. Mesh networks are a type of daisy chaining from one device to
another. This technique expands the typically short range of an individual node
into a much larger, widespread network consisting of multiple nodes.
The Media Access Control (MAC) layer uses a Carrier Sense Multiple Access with
Collision Avoidance (CSMA/CA) mechanism. This layer transmits beacon
requests, synchronizations, and message retries. The physical layer of the ZigBee
network uses the 2.4 GHz radio band. Channels 11 to 26 are available in this band.
Figure 23 illustrates the details and provides a comparison of ZigBee and Wireless
Fidelity (WiFi) network channel spacing.
ZigBee Device Types
The ZigBee specification defines three kinds of devices that can be part of a
ZigBee network: a coordinator, one or more routers, and one or more end devices.
Coordinator
A coordinator is a required network component. Up to eight coordinators are
permitted on each wireless network. The coordinator acts as a parent device,
initiating network formation, which involves channel selection and network
identification. Each Wireless PAN contains one and only one network coordinator.
Router
A router is an optional network component. One or more routers are permitted on
each wireless network. Routers act as parent devices, participating in multi-hop
message routing; they relay messages between nodes and allow child nodes to
connect to them. Routers can talk to other routers and to end devices.
To Next Page
Loading...
Need help?
General
