Telegesis believes ZigBee PRO offers significant advantages for your next design in many key areas of operation such as scalability of large networks, security, network resilience and ease of commissioning. This is why we have chosen it as standard for our range of modules and peripherals to give our customers the best experience of designing with ZigBee.
ZigBee PRO features & benefits
Telegesis believes ZigBee PRO offers significant advantages for your next ZigBee design in many areas of operation such as scalability of large networks, security, network resilience and ease of commissioning. This is why we have chosen it as standard for our range of modules and peripherals to give our customers the best experience of designing with ZigBee.
Telegesis was the first ZigBee module manufacturer in the world to offer certified ZigBee PRO modules and we are now in volume production of modules with this firmware.
The complete range of Telegesis ZigBee products are also available with our AT Command Set based on Ember Corporation’s EmberZNet PRO which is based on the ZigBee PRO Feature Set specification from the ZigBee Alliance.
ZigBee PRO features many improvements but the key features are:
ZigBee PRO uses Stochastic addressing to assign addresses using probability analysis to simplify network formation. In networks which have used a tree cluster approach this can lead to address table ‘churning’ when a new node joins the network, something which can be problematic in large networks.
By using Stochastic addressing nodes do not need a new address when joining a network. In the rare case of a collision the stack provides a conflict resolution system using the unique IEEE address assigned to each node. Another benefit is that the entire 16 bit address space is available to all nodes at any point in the network. This address space is constant even if the network undergoes change such as nodes joining or leaving or a change in the RF environment.
Route Aggregation – ‘many to one’ and source routing
ZigBee PRO networks have the ability to aggregate routes through the use of ‘many to one’ routing. This allows each device to share the same routing path reducing broadcast and network traffic and greatly improves the efficiency and stability of the network routing table
ZigBee’s operation at 2.4GHz is aided by the choice of 16 available channels. The frequency agility function makes using these extra channels easier. When a network is first formed the node seeks a channel with the least noise or traffic. If over time extra traffic appears or noise becomes present the host application can scan for a better channel and move the whole network to the new channel allowing the network to adapt over time to changing RF environments.
Assymetric Link handling
Within a ZigBee network, paths are selected on the quality of RF communication. This quality between nodes is often asymmetric – better in one direction than the other. ZigBee PRO includes Asymmetric Link Handling which uses regular information exchange between nodes to automatically select optimal links greatly improving network performance.
High security operation
ZigBee PRO security is now better than ever; a network wide security key is mandatory and adds further protection for key management and distribution. Energy management is also improved in networks where ZigBee nodes run on batteries where power management is crucial. ZigBee PRO allows end nodes to turn off for fixed periods of time permitting nodes to sleep longer in periods of ‘Hibernation’ or shorter periods of ‘Napping’ as needed by the host application.
Sleeping nodes can however, miss a ‘change network key’ message from the security trust centre in the network. If this happens when a node wakes up it will attempt to communicate using an old key. ZigBee PRO has the ability for the newly awaked node to use a special link to encrypt a message to validate itself with the trust centre and get the new key back in another encrypted link.
PAN ID conflict resolution
Two networks can overlap; something which becomes more likely in large networks. ZigBee uses IEEE802.15.4 as a basic identifier known as the ‘PAN ID’. This allows different logical ZigBee networks even on the same channel. If two networks overlap, giving a PAN ID conflict ZigBee PRO now includes a mechanism to detect and resolve these issues automatically and signal a resolution to a host application.
The ZigBee 802.15.4 spec defines a maximum packet size of 128bytes. This is optimum for short control messages but there may be occasions where the network needs to send larger messages. ZigBee PRO now has the means to automatically fragment and reassemble a message at a receiving node relieving the host application of this overhead.
When a new network is set up each node must be instructed as to which network to join, what security is in place and what command and control relationships are present. This commissioning is usually done with a PC or PDA. ZigBee PRO features a ‘commissioning cluster that has a standard command set useful for typical configuration of new networks. The new security features in ZigBee PRO also means this commissioning can be performed securely.
When ordering any of our products with PRO, please request Firmware R3xx