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Cheatography

Factory Automation Wireless Networks Cheat Sheet (DRAFT) by [deleted]

Compilation of available wireless technologies for factory automation

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Introd­uction

IEEE 802.15.4

IEEE 802.15.4 is designed to support peer-t­o-peer links as well as wireless sensor networks. The standard defines the basic physical layer (PHY), including frequency range, modula­tion, data rates, and frame format, and the media-­acc­ess­-co­ntrol (MAC) layer. Separate protocol stacks are then designed to use the basic PHY and MAC. Several wireless standards use the 802.15.4 standard as the PHY/MAC base, including ISA100a, Wireless HART, ZigBee, and 6LoWPAN.

The standard defines three basic frequency ranges. The most widely used is the worldwide 2.4-GHz ISM band (16 channels), which has a basic data rate is 250 kb/s. Another range is the 902- to 928-MHz ISM band in the U.S. (10 channels). The data rate is 40 or 250 kb/s. Then there’s the European 868-MHz band (one channel) with a data rate of 20 kb/s.

All three ranges use direct sequence spread spectrum (DSSS) with either binary phase-­shi­ft-­keying (BPSK) or offset quadrature phase-­shi­ft-­keying (QPSK) modula­tion. The multip­le-­access mode is carrier sense multiple access with collision avoidance (CSMA-CA). The minimum defined power levels are –3 dBm (0.5 mW). The most common power level is 0 dBm, while a 20-dBm level is defined for longer­-range applic­ations. Typical range is less than 10 meters.

6LoWPAN

Developed by the Internet Engine­ering Task Force (ITEF), 6LoWPAN provides a way to transmit IPv6 and IPv4 Internet Protocols over low-power wireless point-­to-­point (P2P) links and mesh networks. The 6LoWPAN standard (RFC4944), which is short for IPv6 protocol over low-power wireless PANs, also permits the implem­ent­ation of the Internet of Things on even the smallest and remote devices.

The protocol provides encaps­ulation and header compre­ssion routines for use with 802.15.4 radios.
If your wireless device must have an internet connec­tion, this is your technology of choice.
 

Cellular

With services from most network carriers, cellular radio provides data-t­ran­smi­ssion capability for machin­e-t­o-m­achine (M2M) applic­ations. M2M is used for remote monitoring and control. Cellular radio modules are widely available to build into other equipment. Older 2G and 3G modules are now being replaced by 4G LTE modules such as NB-IoT. The working range is from 1 to 10 km, which is the range of most cell sites today.

Dust Networks

Dust Networks was acquired by Linear Techno­logy, which in turn was acquired by Analog Devices. Its SmartMesh technology is based on the 802.15.4 and 6LoWPAN standards. The prime benefit of this technology is its ability to form ad hoc, self-r­epa­iring mesh sensor networks that increase range and reliab­ility. Other key features are its 10,000­-hour batter­y-l­ifetime modules and NIST-grade AES-128 security.

SmartMesh networks commun­icate using a time-s­ync­hro­nized channe­l-h­opping (TSCH) link layer, a technique whereby all nodes are synchr­onized to within a few micros­econds. Network commun­ication is organized into TDM time slots that permit channel hopping and full path diversity. They also offer a version of a HART wired network called Wirele­ssHART (see below).

ISA100a

Developed by the Intern­ational Society of Automa­tion, ISA100a is designed for industrial process control and factory automa­tion. It uses the 802.15.4 PHY and MAC, but adds special features for security, reliab­ility, feedback control, and other industrial requir­ements.

ISM Band

Most of these standards use the unlicensed ISM bands set aside by the Federal Commun­ica­tions Commission (FCC) in Part 15 of the Code of Federal Regula­tions (CFR) 47. The most widely used ISM band is the 2.4- to 2.483-GHz band, which is used by Wi-Fi, Bluetooth, 802.15.4 radios, and many other devices. The second most widely used band is the 902- to 928-MHz band, with 915 MHz being a sweet spot. Modulation is typically ASK/OOK or FSK. Other popular ISM freque­ncies are 315 MHz for garage­-door openers and remote­-ke­yle­ss-­entry (RKE) applic­ations, and 433 MHz for remote temper­ature monito­ring.

RFID

Radio-­fre­quency identi­fic­ation (RFID) is used primarily for identi­fic­ation, location, tracking, and inventory. A nearby reader unit transmits a high-power RF signal to power passive (unpow­ered) tags and then read the data stored in their memory.

RFID tags are small, flat, and cheap, and can be attached to anything that must be tracked or identi­fied. They have replaced bar codes in some applic­ations. RFID uses the 13.56-MHz ISM frequency, but other freque­ncies are also used, including 125 kHz, 134.5 kHz, and freque­ncies in the 902- to 928-MHz range. Multiple ISO/IEC standards exist.

Wi-Fi

Wi-Fi is the commercial name of the wireless technology defined by the IEEE 802.11 standards. Next to Bluetooth, Wi-Fi is by far the most widespread wireless techno­logy. It’s in smartp­hones, laptops, tablets, and ultrab­ooks, as well as TV sets, video access­ories, and home wireless routers. On top of that, it’s deployed in many industrial applic­ations. Wi-Fi is now showing up in cellular networks, where carriers are using it to offload some data traffic like video that clogs the network.

The initial version, called 802.11b, was popular because it offered up to 11-Mb/s data rates in the 2.4-GHz ISM band. Since then, new standards have been developed including 802.11a (5-GHz band), 802.11g, and 802.11n using OFDM to get speeds up to 54 and 300 Mb/s under the most favorable condit­ions.

More recent standards include 802.11ac, which uses multiple input, multiple output (MIMO) to deliver up to 3 Gb/s in the 5-GHz ISM band. Wi-Fi is readily available in chip form or as complete drop-in modules. The range is up to 100 meters under the best line-o­f-sight condit­ions. This is a great option, where longer range and high speeds are needed for the applic­ation.

Wireless HART

HART is the Highway Addres­sable Remote Transducer protocol, a wired networking technology widely used in industry for sensor and actuator monitoring and control. Wireless HART is the wireless version of this standard. The base of it is the 802.15.4 standard in the 2.4-GHz band. The HART protocol is a software applic­ation on wireless transc­eivers.

ZigBee

Emanating from the ZigBee Alliance, this software protocol and technology uses the 802.15.4 transc­eiver as a base. It provides a complete protocol stack designed to implement multiple types of radio networks that include point-­to-­point, tree, star, and point-­to-­mul­tip­oint. Its main feature is the ability to build large mesh networks for sensor monito­ring. And, it can handle up to 65,000 nodes.

ZigBee also provides profiles or software routines that implement specific applic­ations for consumer home automa­tion, building automa­tion, and industrial control. Examples include building automation for lighting and HVAC control, as well as smart meters that implement home-a­rea­-ne­twork connec­tions in automated electric meters. ZigBee is widely used in factory automation and can be used in other M2M and Internet of Things applic­ations as well.