Explanation of Quiz-3

 1: HART & Wireless HART

Introduction:

Wireless HART is the latest release of Highway Addressable Remote Transducer (HART) Protocol.

HART standard was developed for networked smart field devices.  The wireless protocol makes the implementation of HART cheaper and easier.  HART encompasses the most number of field devices incorporated in any field network.

HART Physical Layer:

1. Derived from IEEE 802.15.4 protocol.
2.  It operates only in the 2.4 GHz ISM band.
3.  Employs and exploits 15 channels of the band to increase reliability. 

HART Data Link Layer:

1. Collision free and deterministic communication achieved by means of super‐frames and TDMA. 
2. Super‐frames consists of grouped 10ms wide timeslots.
3.  Super‐frames control the timing of transmission to ensure collision free and reliable communication. 
4.  This layer incorporates channel hopping and channel blacklisting to increase reliability and security.
5.  Channel blacklisting identifies channels consistently affected by interference and removes them from use.

 HART Network & Transport Layers :

1.  Cooperatively handle various types of traffic, routing, session creation, and security.
2.  WirelessHART relies on Mesh networking for its communication, and each device is primed to forward packets from every other device. 
3.  Each device is armed with an updated network graph (i.e., updated topology) to handle routing. 
4.  Network layer (HART)=Network + Transport + Session layers (OSI)

HART Application Layer:

1.  Handles communication between gateways and devices via a series of command and response messages. 
2.  Responsible for extracting commands from a message, executing it and generating responses. 
3.  This layer is seamless and does not differentiate between wireless and wired versions of HART.

2: Z Wave:

1. Zwave (or Z wave or Z‐wave) is a protocol for communication among devices used for home automation.
2.  It uses RF for signaling and control.
3.  Operating frequency is 908.42 MHz in the US & 868.42 MHz in Europe.
4.  Mesh network topology is the main mode of operation and can support 232 nodes in a network.
5.  Zwave utilizes GFSK modulation and Manchester channel encoding.
6. A central network controller device sets‐up and manages a Zwave network.
7. Each logical Zwave network has 1 Home (Network) ID and multiple node IDs for the devices in it.
8. Nodes with different Home IDs cannot communicate with each other.
9. Network ID length=4 Bytes, Node ID length=1 Byte.
10.  Uses source routed network mesh topology using 1 primary controller.
11.  Devices communicate with one another when in range.
12.  When devices are not in range, messages are routed through different nodes to bypass obstructions created by household appliances or layout.
13.  This process of bypassing radio dead‐spots is done using a message called Healing.
14.  As Zwave uses a source routed static network, mobile devices are excluded from the network and only static devices are considered.

3: NFC (Near field communication)

1.  NFC for short, is an offshoot of radio‐frequency identification (RFID).
2.  NFC is designed for use by devices within close proximity to each other.
3.  All NFC types are similar but communicate in slightly different ways.

NFC Types:

1. Passive devices contain information which is readable by other devices, however, it cannot read information itself.
2.  NFC tags found in supermarket products are examples of passive NFC.
3.  Active devices are able to collect as well as transmit information.
4.  Smartphones are a good example of active devices.

Working Principle:

1. Works on the principle of magnetic induction.
2.  A reader emits a small electric current which creates a magnetic field that in turn bridges the physical space between the devices.
3.  The generated field is received by a similar coil in the client device where it is turned back into electrical impulses to communicate data such as identification number status information or any other information.
4.  ‘Passive’ NFC tags use the energy from the reader to encode their response while ‘active’ or ‘peer‐to‐peer’ tags have their own power source.

NFC Applications:

1.  Smartphone-based payments.
2.  Parcel tracking.
3. Information tags in posters and advertisements.
4.  Computer game synchronized toys.
5.  Low‐power home automation systems.

4: Bluetooth:

1. Bluetooth wireless technology is a short-range communications technology.
2.  Intended for replacing cables connecting portable units
3.  Maintains high levels of security.
4.  Bluetooth technology is based on Ad‐hoc technology also known as Ad‐hoc Piconets.

Features:

Bluetooth operating range depends on the device:

1. Class 3 radios have a range of up to 1 meter or 3 feet
2. Class 2 radios are most commonly found in mobile devices have a range of 10 meters or 30 feet.
3.  Class 1 radios are used primarily in industrial use cases have a range of 100 meters or 300 feet.

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