Top 100+ Zigbee Interview Questions And Answers
Question 1. What Is The Zigbee Alliance?
Answer :
The ZigBee Alliance is a non-benefit industry consortium of driving semiconductor producers, innovation suppliers, OEMs and end-clients around the world. Individuals target characterizing a worldwide determination for interoperable, practical, low-power remote applications dependent on the IEEE 802.15.4 norm. Current participation is around 200 and incorporates the two heavyweights, (for example, Siemens and Texas Instruments) and little new businesses.
Question 2. What Is The Goal Of The Zigbee Alliance?
Answer :
The objective of the ZigBee Alliance is to make an open determination characterizing lattice and tree arrange topologies with interoperable application profiles for remote control frameworks. Its emphasis is obviously on measures based, minimal effort, low-force, and low-information rates applications. Intends to affirm items are additionally inside the extent of the ZigBee Alliance.
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Question 3. Who Is Supporting The Zigbee Alliance Today?
Answer :
Industry pioneers worldwide have focused on giving ZigBee-agreeable items and arrangements. Part organizations incorporate 13 advertisers (BM Group, Ember, Free scale, Honeywell, Huawei, Mitsubishi Electric, Motorola, Philips, Samsung, Schneider Electric, Siemens, STMicroelectronics, and Texas Instruments) and members that contain semiconductor makers, remote licensed innovation suppliers and OEMs.
As of not long ago the ZigBee Alliance used to be overwhelmed by semiconductor producers and innovation suppliers. Since 2006 enormous OEMs like Siemens and Schneider Electric have joined the Board of Directors. They are relied upon to bring to the Alliance a more application-driven center, which will be instrumental in accomplishing the guarantee of item and seller interoperability.
Despite the fact that the ZigBee Alliance used to be so far very US-driven, enrollment has fundamentally developed in Europe and Asia. Supporting organizations are currently spread everywhere throughout the world.
Question 4. What Are The Typical Applications Promoted By The Zigbee Alliance?
Answer :
Since its commencement ZigBee innovation has been planned as a universally useful low-information rate, low-power remote arrangement. In opposition to contending advancements, (for example, Z-Wave, which centers around home control), ZigBee has an extremely wide application scope. Commonplace models incorporate home mechanization (lighting, warming, terminations, security, access to set-top boxes), building computerization (lighting, HVAC, smoke recognition, get to control), mechanical checking, programmed meter perusing, ecological information assortment, and clinical detecting.
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Question 5. Which Zigbee Alliance Members Are Active In Residential And Building Automation?
Answer :
Control4, Danfoss, Eaton, Grundfos, Hitachi, Honeywell, Hubbell, Invensys, Johnson Controls, Legrand, Marlin Controls, Mitsubishi Electric, Nice, Niko, Philips, Schneider Electric, Siemens, Trane, Urmet Domus, Vantage Controls, Viconics, and Yamatake.
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Question 6. Which Zigbee Alliance Members Are Active In Industrial Automation?
Answer :
Crane, Eaton, Grundfos, Hitachi, Honeywell, Invensys, Legrand, Mitsubishi Electric, Omron, Schneider Electric, Siemens, Yamatake, and Yokogawa.
Question 7. Which Zigbee Alliance Members Are Active In Automated Metering?
Answer :
Holley Metering, Itron, and Schneider Electric.
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Question 8. Are There Several Zigbee Versions?
Answer :
Right now, the open update of the detail is ZigBee 1.0 (dated December 2004). It incorporates the system layer, the application layer, and the 'Home Controls, Lighting' (HCL) application profile (which will be supplanted by another profile in the following modification). ZigBee 1.0 does exclude any authorizing suggestions, nor does it determine a specific stack profile since just tree tending to is characterized.
The following open correction of ZigBee is 1.1, which ought to be accessible by end 2006. It will incorporate propelled highlights permitting to withdraw from current impediments forced by tree tending to and brought together authoritative. New application profiles, alongside relating dispatching systems, will likewise be discharged.
A few sellers, for example, Ember, give ZigBee stacks that are in front of the present determination. Propelled highlights are then frequently brought to the ZigBee Alliance to be remembered for the following authority update.
Question 9. What Are The Various Zigbee Stack Profiles?
Answer :
ZigBee 1.1 will incorporate two stack profiles:
'ZigBee' (earlier 'Home Controls') targets less difficult, littler systems that commonly work in a private situation. Tending to is acted in a tree style, security execution is genuinely straightforward, and application ties occur in the facilitator in a brought together way. The comparing detail is currently finished.
'ZigBee Pro' (in the past 'Business, Industrial and Institutional') targets bigger and increasingly advanced systems. Tending to and steering are progressively versatile, security is increasingly hearty, and propelled highlights, for example, multicast are incorporated. Additionally, 'ZigBee Pro' targets giving negligible dependence on the organizer through appropriated application ties. The comparing detail ought to be finished by end 2006.
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Question 10. What Are The Various Zigbee Application Profiles?
Answer :
ZigBee 1.0 incorporates the 'Home Controls, Lighting' (HCL) application profile, which gives fundamental definitions to basic private lighting applications.
ZigBee 1.1 will incorporate extra application profiles:
'Home Automation' (HA) replaces and extends HCL. It depends on 'ZigBee' stack profile and characterizes a lot of gadgets for use in home conditions: switches, indoor regulators, window conceals, radiators, and so forth. The relating determination is practically finished.
'Business Building Automation' (CBA) targets enormous structure frameworks and depends on 'ZigBee Pro' stack profile. The detail incorporates gadget depictions for lighting and HVAC the executives, for example. It ought to be accessible by end 2006.
'Modern Plant Monitoring' (IPM) incorporates gadget definitions for sensors and actuators utilized in mechanical control: temperature, pressure, infrared, and so forth. The relating detail ought to be finished by end 2006.
Other continuous activities spread extra applications inside the extent of ZigBee:
'Remote Sensor Applications' (WSA) will give highlights to diminishing force utilization in switch gadgets and permit them to be in dozing mode.
'Telecom Applications' (TA) will address new situations around the utilization of cell phones in private or tertiary conditions.
'Programmed Meter Reading' (AMR) targets metering applications however is today waiting.
Question 11. What Is The Zigbee Commissioning Framework (zcf)?
Answer :
The reason for the ZigBee Commissioning Framework (ZCF) is to determine normalized methods of shaping and designing ZigBee systems. This incorporates the meaning of general authorizing modes (completely programmed, with or without charging apparatus) and reliable techniques to enact ZigBee gadgets. The ZCF will be accessible in modification 1.1 and meets up with HA and CBA application profiles.
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Question 12. What Are The Various Zigbee Certification Mechanisms?
Answer :
The ZigBee Alliance has characterized three affirmation levels:
The ZigBee Compliant Platform (ZCP) affirmation is accessible today for equipment and programming innovation suppliers. So far 13 merchants have had their ZigBee stage guaranteed.
The ZigBee Network Capable (ZNC) affirmation targets items that utilize a private ZigBee application profile notwithstanding an agreeable stage. The approach is being intended to permit simple self-accreditation and the utilization of a logo.
The ZigBee Certified Product level gives interoperability different sellers since it requires the utilization of an open ZigBee application profile notwithstanding an agreeable stage. A particular test plan goes along every open application profile discharged by the ZigBee Alliance.
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Question 13. Is It Possible To Deploy Zigbee Networks In Sub-ghz Bands?
Answer :
Truly, it is. ZigBee can utilize IEEE 802.15.4 physical interfaces transmitting at 868 MHz or 915 MHz. Information rates are decreased to 20 kbps and 40 kbps, individually. The remainder of the convention stack is equivalent to in ZigBee executions at 2.4 GHz.
Question 14. What Is The Typical Communication Range Of Zigbee?
Answer :
Range relies upon various elements including the general condition, handsets' qualities, radio wire configuration, yield power, and so forth. A portion of these parameters can be improved to expand the range in explicit engendering conditions. Utilizing the present off-the rack ZigBee radios at an ostensible yield intensity of 0 dBm, common qualities are 10 to 50 m indoor and around 100 m open air, more if there should arise an occurrence of immaculate view.
Question 15. What Is The Typical Battery Lifetime Of Zigbee End Devices?
Answer :
Battery lifetime is an element of numerous parameters, for example, battery type, limit, obligation cycling and end-use application. Various radios and smaller scale controllers include various degrees of intensity utilization, which at last influence battery lifetime. The present off-the rack ZigBee parts working under low obligation cycles take into account run of the mill lifetimes involved somewhere in the range of 5 and 10 years. Applications like programmed meter perusing that require significantly sparser transmissions may surpass 10 years.
Further upgrades in power utilization are anticipated with the expanding accessibility of single-chip ZigBee arrangements (coordinating the radio and the small scale controller on a similar chip).
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Question 16. Is It Possible To Have Battery-fueled Zigbee Routers?
Answer :
ZigBee switches are today thought to be mains-fueled. The low-power switch usefulness is relied upon to be a piece of the ZigBee particular sooner rather than later. This activity is driven by the 'Remote Sensor Applications' (WSA) work gathering.
Question 17. Does The Zigbee Coordinator Represent A Single Point Of Failure?
Answer :
All ZigBee systems require an organizer, which is liable for arrange development. In ZigBee 1.0 and in 'ZigBee' stack profile, the facilitator moreover has the coupling table and along these lines turns into a frail point. Systems to manage facilitator breakdowns, (for example, duplication of the coupling table) are execution issues and out of the extent of update 1.0.
ZigBee 1.1 will have systems to manage facilitator disappointments and oversee decentralized restricting tables. The facilitator won't be anything else in danger of turning into a solitary purpose of disappointment.
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Question 18. How Is Addressing Performed In Zigbee?
Answer :
In ZigBee 1.0 and in 'ZigBee' stack profile, hubs are sensibly sorted out as a tree. Switches branch out in a tree-like way from the facilitator, with end gadgets commonly being tired gadgets. Tending to is performed progressively by following the tree structure.
In 'ZigBee Pro' stacks profile, there is no sensible tree structure. System addresses are haphazardly ascribed, with potential location clashes settled along these lines.
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Question 19. How Is Routing Performed In Zigbee?
Answer :
In ZigBee 1.0 and in 'ZigBee' stack profile, directing is at first performed deterministically, along the parts of the tree structure. Tree steering implies that subsequent courses are at times backhanded and accept that the system topology is static. As a subsequent advance, table steering can be utilized to alternate route the tree and find new courses.
In 'ZigBee Pro' stack profile, just table directing is permitted. Along a course, each middle hub utilizes its own steering table to advance the parcel to the following hub, until the bundle arrives at its goal. For a specific goal, every hub stores the following bounce data in its steering table.
Question 20. What Is The Zigbee Cluster Library (zcl)?
Answer :
The ZigBee Cluster Library (ZCL) is a huge expansion to correction 1.1. In ZigBee, a bunch is a message or assortment of messages relating to a given application space. A few gadgets, (for example, on/off switches) have a similar definition and usefulness whatever application profile is utilized. The thought behind making the ZCL was to give group reusability by abstracting bunches over a few application spaces and putting them in a library sorted out as per utilitarian areas (e.g., lighting, terminations, HVAC).
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Question 21. Is Multipath Fading A Chief Concern For Zigbee?
Answer :
Multipath blurring impacts every single remote transmission. Coming about radio signs arrive at the accepting reception apparatus by a few ways, prompting signal obstruction and stage moves that can cause blunders and influence the connection quality. This marvel will in general be ignored in work systems since information parcels can go through option steering ways if there should arise an occurrence of correspondence disappointment. While multipath blurring may not be a worry for thickly coincided ZigBee systems, it unquestionably is for single point-to-point joins.
Question 22. Are Zigbee Networks Scalable?
Answer :
ZigBee tending to plan can bolster up to 65'535 hubs per organizer, and different facilitators can be connected together to build the general size. This breaking point clearly is hypothetical and doesn't ensure legitimate activity of such an enormous system. Adaptability will profoundly rely upon the application prerequisites as far as thickness, traffic load and satisfactory idleness.
With minimal test material accessible for extremely huge systems, it is anyway sheltered to expect that such enormous systems will be enough sorted out into geological groups. Expanding on the continuous ZigBee Alliance's work with respect to IP passages, one can likewise envision connecting a few ZigBee organizes through rapid IP spines that as of now exist in numerous situations.
Question 23. Are Zigbee Networks Secure?
Answer :
The ZigBee determination incorporates arrangements for security and information uprightness dependent on get to control records, parcel newness clocks and 128-piece AES encryption. It is genuinely sheltered to expect that these are sufficient for private and generally business and modern applications.
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Question 24. Does Zigbee Have A Transport Layer?
Answer :
No, the ZigBee determination doesn't characterize a vehicle layer. Since most ZigBee information trades target basic and little messages, the subject of guaranteeing start to finish information conveyance has been left to the item merchant. The last can decide to incorporate that capacity as a component of its application.
Some stack merchants, for example, Ember, give an extra vehicle layer that ensures dependable start to finish informing and rearranges application advancement. This element is anyway not indicated in the norm and will along these lines be utilized in mix with private application profiles.
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Question 25. Will Products Based On Different Zigbee Stack Profiles Be Interoperable?
Answer :
No, they won't. 'ZigBee' and 'ZigBee Pro' stack profiles don't depend on the equivalent tending to and steering plans, which forestall interoperability.
Question 26. Is Zigbee A Competitor For Bluetooth?
Answer :
ZigBee and Bluetooth have been created to serve diverse application spaces. Bluetooth targets higher information rates and better QoS to ship more extravagant media (ordinarily voice signals). ZigBee passes on a lot more straightforward messages across increasingly versatile systems that require low obligation cycling without close synchronization.
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Question 27. Is Zigbee A Competitor For Wifi (ieee 802.11b/g)?
Answer :
ZigBee and WiFi obviously address exceptionally unmistakable application necessities. Cost and force utilization examples of WiFi can't fit remote control needs, though ZigBee transmission capacity is by a wide margin too low to even think about transmitting enormous information streams.
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Question 28. Is Zigbee A Competitor For Z-wave?
Answer :
ZigBee contends with Z-Wave in the home robotization space. As an innovation concentrated on the home control fragment solely, Z-Wave has been quicker than ZigBee in bringing its convention stack to the market. While Z-Wave is a solitary source innovation, ZigBee appreciates multi-sourcing and depends on an IEEE standard. Moreover, ZigBee gives higher information rates and works in both 2.4 GHz and sub-GHz unlicensed groups.
Question 29. Are There Yet Zigbee Products On The Market?
Answer :
Indeed, there are. Some actualize a real ZigBee stack while others include a ZigBee prepared stage like Ember Net.
Models in the private space incorporate Control4 (lighting), Eaton (home mechanization), Golden Power Manufacturing (sprinklers and indoor regulators), Hawking Technology (home doors), Kalirel (warming), Mija (fire dousers), Nice (shades), and TSC Systems (home computerization).
Models in the business space incorporate Mija (fire quenchers), Philips (lighting), Siemens (building robotization), and TAC (building computerization).
