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Moxa ANT-WSB-ANM-05 network antenna

1. innovative push based architecture so that less maintenance effort and lower level hardware devices can be implemented WWW moxa com info moxa com 62 Automatic Tag Generation Active OPC Server Lite and ioLogik series products support Auto Tag Generation which eliminates the headache of specifying target IP addresses I O channels and data formats one by one or editing and importing configuration text files since Active OPC Server Lite creates the tags for the target ioLogik automatically Simply select the channels that you need to update and the tags are generated and configured automatically Generally speaking tag generation is 50 times faster with Active OPC Server Lite than with traditional OPC server packages One of the biggest payoffs is that users will no longer need to be trained to install and configure your OPC It takes 2 5 minutes to create only 1 tag Just 5 seconds to create 20 or more tags Sereer Active OPC Server No queries ioLogic Dynamic IP WAN Connection Unlike the fixed IP requirements of Ethernet I O with a traditional OPC server Active OPC Server Lite and ioLogik products provide the flexibility of configuring the ioLogik to use dynamic IP addresses The ioLogik connects directly to the Active OPC Server Lite instead of being polled which makes dynamic IP addressing and WAN Access to the Ethernet I O device possible and adds
2. 29 WWW moxa com info moxa com 2009 Industrial Wireless Guidebook Moxa s Antennas Selection Guide IEEE 802 11b g 2 4 GHz Wireless Antennas lu a UU ANT WSB ANF 09 ANT WSB PNF 12 ANT WSB PNF 18 E Plane E Plane s hr A Se rpm tns be e Fu ur Tx si d zt LJ m i EE S ae ag Mi 9 L a 1 d H Plane H Plane o T n PE PS an A ks io tn r DM aii L VS T3 etd KS Ja i et E MALLE Eu era WP ee miu e Q pate zt 2 paT RIN pum uu z 2 4 to 2 5 GHz 2 4 to 2 5 GHz 2 4 to 2 5 GHz 2 4 to 2 5 GHz M Diple M Diple Omni directional Directional Panel Directional Panel 50 5 ohms 50 5 ohms 50 5 ohms 50 5 ohms id 0 EN 0 13412 se 1 45 Max 1 45 Max EE 15 W Max 10 W Max 15 W Max HP SMA male N type female N type female N type female 40 to 80 C 40 to 80 C 40 to 80 C 40 to 80 C C Q D T e D 5 Q 5 a 5 Q c T e ES 2 c m ITI m Co O N i IDEM a ENS IP65 S O 420 mm length 215 x 90 x 30 mm 2 0 x 205 x 15 mm 300 g 430 g 560 g 1020 g WWW moxa com info moxa com 20 4 Understanding Industrial WLAN IEEE 802 1 Memm W IEEE 802 11a b g 2 4 5 GHz Dual band Antennas ANT WDB ANF 0609 E Plane 2 4 GHz UL ju sg a e t E Ife 2 4 to 2 5 5 1 to 5 9 GHz Omni directional 6 9 dBi 50 5 ohms 10 8 1 1 5 Max 10 W Max N type female 7 40 to 80
3. D rk lt O A 0 Reverse Real COM mode diagram WWW moxa com info moxa com 52 Cellular Networks oo Socket Mode Standard TCP IP Connection TCP Server Client If your application involves a socket based TCP server or TCP client you can set your OnCell G3100 device to Socket Mode Socket operation mode by simply using the OnCell web console You do not need to install any additional utilities onto the host PC but the socket software on the host PC will need to set up a socket connection with the OnCell G3100 The IP address of the SIM card on the OnCell G3100 device will determine the role of socket connection OnCell Device s IP Address Suitable Role Socket Mode Selection Public address Server role Client role TCP Server TCP Client Private IP address i Like 10 x y x or 172 xx Client role TCP Client If both the host PC at the control center and the OnCell G3100 device have private IP addresses you can use OnCell Central Manager on the OnCell G3100 to resolve the private IP to private IP problem and select TCP Server for the OnCell G3100 s socket mode 1 IP gateway play TCP Server role gn IP gateway play TCP Client role 53 WWW moxa com infogmoxa com 2009 Industrial Wireless Guidebook Short Message Connection SMS Tunnel Short Message Service SMS is a very popular service offered by cellular providers You can send and receive serial data via SMS by setting up t
4. PPP Dial out to PPPD Dial In y WWW moxa com info moxa com 54 Cellular Networks o 2 The originating OnCell device dials the phone number of the ISP Internet Service Provider just like an analog modem Normally ISPs offer free accounts and passwords for you to access the Internet f PPP to Internet via ISP s Hos IP Gateways and GPRS GPRS is designed for packet data communication and provides GSM users with access to the Internet from a cellular network Before activating the GPRS function on your OnCell G3100 make sure that the SIM card is GPRS enabled with the right APN string In order to activate GPRS service on your OnCell device your SIM card must first be connected to a GSM network That is why the GSM LED on your OnCell device will be lit for a while before the GPRS LED turns on You will also need the APN Access Point Name and account password not required by some cellular providers The APN is a string that determines which Internet gateway GGSN from the cellular provider s network you can access This may affect the IP address and services such as port blocking and VPN you are able to obtain from your provider Cellular providers also maintain a database HLR to record and bill your service level S Cy fF GPRS mode to Internet Wir q If your SIM card is already GPRS enabled and has the right APN then your OnCell G3100 will automatically set up the IP link for your appl
5. or in the server specific settings Remember that OPCEnum requires the Anonymous Logon access You may wish to remove this access The consequence of this action will simply be that OPC Users will be unable to browse for OPC Servers on the specific computer where Anonymous Logon access is not available However users will indeed be able to properly connect to and exchange data with the OPC Server 65 WWW moxa com info moxa com 2009 Industrial Wireless Guidebook We encourage you to complete your DCOM setup with this step Integrators freguently establish OPC communication and don t spend the necessary time to secure the computers again This can lead to catastrophic results if network security is compromised due to a virus worm malicious intent or simply unauthorized experimentation by well meaning coworkers For more detail information please refer to the OPC Training Institute http www opcti com i Enhance OPC Capability for Cellular Communications GPRS is a communication technology that allows data acquisition systems to overcome the difficulty of cabling for wide area remote sites GPRS applications are becoming more and more prevalent due to the ease with which they can be implemented but the dynamic IP address issues associated with GPRS networking continue to frustrate system integrators The fact that most GPRS devices use dynamic IP addresses can be somewhat frustrating What this means is that telecom s
6. Ethernet devices connected to the OnCell device Virtual Server Settings Virtual Server Setup Virtual server Enable Disable No IZ Activate Protocol Public Port Internal IP Internal Port 1 e TGP 502 1 192 168 1 1 502 2 E TCR 80 192 168 1 1 80 3 E TCP v 4 D TEP v 5 LI TCP w 5 O Tce 7 Li TCP v 5 9 TCP Submit As you can see virtual server setting is basically setting the forwarding ports For example you select an available public port that the OnCell s WAN IP will be listening on A TCP client device will connect directly to the OnCell s WAN IP Public Port when making a TCP connection with the server Next enter the actual server s IP address Internal IP to allow the OnCell to locate the server in the local network An internal port listening port on the actual server is then specified so that the traffic coming through from the public port will be forwarded to the internal port Lastly you ll notice that both TCP and UDP traffic can be forwarded by the virtual server The previously mentioned DDNS function can be enabled on the OnCell device to compensate for dynamic WAN IP addresses DDNS Configuration DONS M Enabla O Disable Server address DynDns org Host name moxaiw dyndns org Username moxaiw Password LLLE Submit 57 WWW moxa com infogmoxa com 2009 Industrial Wireless Guidebook i From LAN to WAN Cy fF Cup st We now switch the rol
7. Server Lite is a software package provided by Moxa that operates as an OPC driver for an HMI or SCADA system It offers seamless connection from Moxa s ioLogik series products to SCADA systems including Wonderware Citect and iFix Active OPC Server Lite meets the latest standard of OPC DA 3 0 which allows connections to various kinds of devices and host OPC machines SCADA System Moxa Active Traditional OPC Server OPC Sarver Push Polling Architecture Architecture rg N f Moxa Active Ethernet 1 0 Devices VO Devices i Communication from 1 0 to SCADA There are many kinds of communication methods between SCADA HMI software and remote devices such as I O devices RTUs or PLCs In the past proprietary protocols were provided by device manufacturers who always supplied drivers to make their devices compatible with SCADA HMI software or provided their own SCADA software Today Modbus protocol is quickly becoming the standard among hardware manufacturers with SCADA HMI software vendors also jumping on the wagon Although Modbus offers compatibility between most devices and SCADA software not all devices support Modbus protocol Achieving a standard mechanism for communicating with numerous data sources such as devices on the factory floor or a database in a control room is the motivation for the development of OPC SNMP protocol is used in IT to manage various Ethernet devices and OPC Client Server architecture supports SNMP Moxa s innova
8. Service providers such as web portals and e mail servers use a fixed domain name Clients such as mobile phones get information from these service providers by pushing the connection request to the Web and e mail servers and when a connection is established the communication is bi directional Unlike the so called polling architecture push technology makes bi directional communication possible for GPRS networks that are using either a dynamic or a static IP address A remote device with front end intelligence can report its I O status to the host and connect to the GPRS network when it needs to Since Moxa s Active OPC Server supports push technology our GPRS I O family of products creates a software based gateway that makes communications easier By using a static IP address on the Active OPC Server the GPRS I O device can connect to the GPRS network and Active OPC Server without needing to worry about the IP address issues The topology is described below li establish 2 Ae Compared with polling architecture push technology not only solves the IP address issues but also reduces network loading as well as bandwidth consumption Moxa s ioLogik W5340 Active GPRS l Os takes full advantage of all the benefits of push technology and Active OPC Server What Active GPRS I O and Active OPC Server provide are 1 SCADA Data Acquisition by OPC protocol 2 SCADA Data Acquisition by Modbus TCP protocol 3 ioAdmin exe active GPRS l O s confi
9. Transmit Power 4 1 o P Gt Gr Pr 20 GGI Y 41 88 x f t F L d P f Mad Pr Sensitivity f is the frequency in mHz pt and pr in dBm and gt and gr in dBi which are easier to obtain from product specifications To get the effective range d in km all we have to do is plug in the values for pt pr gt gr and ja WWW moxa com info moxa com Gt Gr Antenna Gain E LL Z09 333l NVIM Ieuisnpu Buipuejsjepuf Understanding Industrial WLAN IEEE 802 11 9 The receiver s sensitivity is the minimum power level the receiver can accept to process the received data The specified sensitivity is not the power detected by the receiving antenna but the power present as the receiver module An important point to note from the above eguation is that as freguency increases the effective distance decreases Therefore the 802 11a 5 GHz standard will yield a shorter communication distance than 802 11b g 2 4 GHz Users who wish to communicate long distances should therefore select 802 11b g as their operating standard Bandwidth Data Rate and Throughput Usually when bandwidth is mentioned it means one of two things 1 The actual width of a frequency band measured in Hz Hertz the effective bandwidth would be the frequency band that is actually carrying data 2 The maximum data rate available bits per second in a communication link The former is the technically correct definition of bandwid
10. are necessary to extend the wireless range The following sections contain a brief description of the two types of antennas e Omni directional antennas transmit horizontally with equal power in all directions They have very limited vertical spread which determines the antenna gain Antennas of this type are typically located in the center of open spaces or larger offices to provide even coverage to all clients E Plane H Plane ii Fiberglass Antenna Dipole Antenna e Uni directional antennas have beams with narrow horizontal and vertical angles Uni directional antennas are mainly used on rooftops or masts for establishing point to point links that interconnect areas of a network that are separated by a distance LL 208 333l NYIM Ieuisnpuj Guipuejs1apun E p E Plane H Plane Directional Panel Antenna WWW moxa com info moxa com 26 Understanding Industrial WLAN IEEE 802 11 9 i Setting Up Point to Point Connections This sector introduces the basic principles involved in designing point to point links and provides tips on aligning the antennas The following basic questions must be answered when designing long range wireless links e What antennas are required for the desired application e How must the antennas be positioned to ensure a problem free connection e What performance characteristics do the antennas need to ensure sufficient data throughput within the legal limits MOXA Antenna Calcu
11. are some potential limitations when a wireless VLAN reaches a certain scale The first limitation arises from its 12 bit VLAN identifier VID The size of the VID limits the number of wireless VLAN to 4094 The number might look big enough to accommodate most WLAN applications However as wireless applications grow at a tremendous pace it will soon be not enough for some large scale WLAN applications Large scale Wireless VLAN also causes the second and third limitations That is when the Wireless VLAN grows too large traffic flowing through the routers also increases This large volume of traffic makes routers another potential bottleneck for the Wireless VLAN The third constraint is the potential security loopholes As the VLAN grows there is a possibility that the wireless VLAN will stretch over large geographical areas that require the VLAN to pass through a third party network This creates security loopholes as there is almost nothing to stop the virus from spreading inside the VLAN WWW moxa com info moxa com Understanding Industrial WLAN IEEE 802 11 oo i QoS for Video Audio and Control The dramatic growth of WLAN has also led to demands for video and audio transmission over WLAN Quality of Service QoS is therefore becoming an important topic for wireless communications QoS is a network term for controlling and measuring data transmission rates throughputs and error rates QoS is not of a big concern for simple data t
12. area is adjacent to a Class Division 1 location Zone 2 This is defined as an environment where an explosive gas atmosphere is not likely to occur during normal operation but could occasionally arise for brief periods of time ATEX Class Division 2 in Oil amp Gas Industry Safety is of the utmost importance and cannot be negotiated in dangerous industrial environments In particular oil and gas exploration sites as well as energy field development production and transportation facilities face a real risk of explosions Therefore engineers must ensure prior to installation that all the equipment and protection systems have to meet or exceed regulatory standards used under hazardous conditions Moxa Offers Specifically Designed for Hazardous Sites Designed with the highest safety standards in mind Moxa s AWK series of WLAN solutions are constructed in strict accordance with global acceptance for explosion protection in hazardous locations Product offerings include rugged AWK 3121 and AWK 4121 With ATEX Class 1 Division 2 and UL C1D2 certifications these stringently proven WLAN products help build safe and reliable networks in the oil and gas industry WWW moxa com info moxa com 2009 Industrial Wireless Guidebook Chapter 3 Cellular Networks 3 1 Cellular Basics What is Cellular Cellular is a radio based communications system that enables customers to call and be reached over a wide area supporting both h
13. communication speed to reach a theoretic number of 300 Mbps Since the theoretic speed of this new standard now called IEEE 802 11n needs to reach 300 Mbps the Physical Layer also needs to support a higher transmission speed that is at least 50 times faster than IEEE 802 11b and 10 times faster than IEEE 802 11g In addition to enhancing communication speed IEEE 802 11n also extends the communication distance to satisfy the growing needs of wireless applications To make this happen IEEE 802 11n has added more specifications to the MIMO standard that allows IEEE 802 11n to be able to use multiple antennas to increase transmission speed It also uses Alamouti coding schemes to increase the transmission coverage There are two rival camps competing to dominate the IEEE 802 11n Physical Layer architecture the World Wide Spectrum Efficiency which is supported by Broadcom and TGnSync supported by Intel and Philips i IEEE 802 11s An 802 11s mesh network device is referred to as a mesh station mesh STA Mesh STAs form mesh links with one another over which mesh paths can be established using a routing protocol 802 11s defines a default mandatory routing protocol or HWMP yet allows vendors to operate using alternate protocols HWMP is inspired by a combination of AODV RFC 3561 1 and tree based routing Mesh STAs are individual devices using mesh services to communicate with other devices in the network They can also collocate with 802
14. even greater flexibility by allowing connections across firewalls I O devices for traditional data acquisition applications are not capable of using this approach 1 OPC Fundamentals OPC OLE for Process Control is an industry standard created by the collaboration of a number of leading worldwide automation hardware and software suppliers working in cooperation with Microsoft The standard defines methods for exchanging real time automation data between PC based clients using Microsoft operating systems The OPC Specification is a non proprietary technical specification that defines a set of standard interfaces based upon Microsoft s OLE COM DCOM platform and NET technology The application of the OPC standard interface makes possible interoperability between automation control applications field systems devices and business office applications Traditionally each software or application developer was required to write a custom interface or server driver to exchange data with hardware field devices OPC eliminates this requirement by defining a common high performance interface that permits this work to be done once and then easily reused by HMI SCADA control and custom applications OPC simplifies system integration in a heterogeneous computing environment However functions such as security batch and historical alarm and event data access belong to the features that are addressed OPC interfaces can be used in many places within an appl
15. is also required for domain name access i The OnCell can be both TCP Server and TCP Client In some applications Ethernet devices act in both the server and the client role In these cases the OnCell can play both roles as well The virtual server settings and gateway settings can be used simultaneously in the same way a traditional router can forward traffic in both directions As shown in the network diagram below you only need two OnCell devices for two Ethernet devices to communicate with each other The Ethernet devices do not need to be located in a hardwire Internet ready area as long as there is a cellular signal present and the TCP Server Client pair of the OnCell device can bridge a LAN connection TGP eant lienas WWW moxa com info moxa com 58 Cellular Networks gt 3 6 How to Connect 1 0 Devices to Cellular Networks i SCADA Meets Ethernet SCADA Supervisory Control and Data Acquisition is a computer based industrial control system that plays an important role in the field of automation today In particular SCADA systems are used to monitor and control a process including manufacturing production power generation fabrication refining water treatment distribution wastewater collection and treatment oil and gas pipelines electrical power transmission and distribution facility processes and more Some of the benefits provided by SCADA include e Setting up Communications for Data Acquisitions e
16. range however WLAN systems are still limited to local area networks and places with hardwire Internet connections What if Ethernet devices could be accessed through a cellular network This would allow Ethernet devices to be accessible almost anywhere as long as cellular coverage is available Ethernet to cellular technology can also provide primary and backup network connectivity Moxa offers an easy and cost effective means of connecting virtually any remote location or device to a corporate IP network It is ideal for applications where wired networks e g lease line frame relay CSU DSU fractional T1 are not feasible or where alternative network connections are required i From WAN to LAN TCP Server SYIOMJAN JeJNIj2D E In this case the Ethernet device when acting as a server is to be reached from the public domain The TCP Server may be an industrial PC server an I O device with LAN interface or any Ethernet routing device As long as the device uses a LAN interface running on TCP protocols even MODBUS TCP the device can be reached There may even be multiple Ethernet devices with different IP addresses connected to the IP gateway When a TCP Client device attempts to connect to the TCP Server it will first need to make a TCP connection with the IP modem OnCell and then have the OnCell port forward the synchronization request to the TCP Server connected to it Basically the OnCell plays the role of a virtual serv
17. settings After opening the DCOM setting windows find the OPC Server to configure and right click on it Select the Properties option in the list of objects in the right window pane Choice the XThe system account services only The OPC Server will take the identity of the Operating System or System for short This is typically the desired setting for the OPC Server as the System Account is recognized by all computers on the Workgroup or Domain In addition no one needs to be logged on the computer so the OPC Server can execute in an unattended environment Disable this option if the OPC Server is not setup to execute as a Windows Service If this is the case simply configure the OPC Server to execute as a service before configuring this setting Restore Windows Security Once you establish the OPC Client Server communication it is important to secure the computers again This includes but is not limited to a Turn on the Windows Firewall again This will block all unauthorized network traffic You will also need to provide exceptions on two main levels e Application level specify which applications are able to respond to unsolicited requests e Port and protocol level specify that the firewall should allow or deny traffic on a specific port for either TCP or UDP traffic b Modify the Access Control Lists ACLs to allow and deny the required User Accounts This can be accomplished either through the system wide settings of DCOMCNFG
18. the developing world to link communities separated by difficult geography with little or no connectivity options In this section we will introduce long distance wireless technology and list the components required to extend your wireless range 1 Application Topology Wireless Link AP Client Mode By setting up a wireless link between the AP and Client several buildings in an extensive corporate campus can be easily integrated into the company network AP Client connections can also be used to provide Internet access in areas where cabling would be too expensive or impractical to install A good LOS Line of Sight is required between the AP and Client devices Distances of several kilometers can be bridged by this type of wireless link Ethernet Mobile Device Panel PC AP Client Operation Wireless Distribution System WDS Wireless Distribution System WDS is a special type of wireless link This mode allows several buildings on a company to be connected to the central office The central AP is configured the partner MAC Media Access Control the remote WDS AP is configured the central AP MAC Media Access Control The wireless link will reduce half bandwidth due to use the same frequency channel when add more one AP under chain connection nt 4 Enabled clie wos Link go2 1 e 23 a WWW moxa com infogmoxa com 2009 Industrial Wireless Guidebook Wireless Bridge System Dual RF Mo
19. this SSID to the AP Figure Single RF Connection SSID2 2 WLAN Bassi Seung BRZ Houx fastum SSID Lacra sn Nee RT Vbi Ya 8 TAL ERI bomo mom moe m m m D LL 208 333l NV 1M Ieuisnpuj Guipuejsaepur E ALAS with seme color must have deta AF type 5506 and security settings In addition to wireless redundancy mode Moxa s AWK 5000 6000 advanced AP Client devices offer another dual RF feature called Wireless Bridge mode This is designed to optimize WDS mode because of the throughput problem for WDS The normal eruption for throughput is throughput 25Mbps n 1 where n is the nodes number for WDS With Wireless Bridge mode we can keep the throughput at 10 to 15 Mbps Configuration is simple simply link the Wireless Bridge master to the Wireless Bridge slave as shown below Single RF Mesh Network 25M Throughput Ps EE Ex Around 8Mbps with 4 mesh nodes Poor Performance WWW moxa com info moxa com 38 Understanding Industrial WLAN IEEE 802 11 9 Figure Wireless Operation Mode Bridge Mode Op ain it mcdia i ieri i WLAN i agerstion mode Cp xem WLAN 2 open ein mode APF Clant LAN 1 namamazaxa MANT WAS mM il AS 2 WLAN cocoon my il AS 2 e i i 6 6 5 U A GA A LA A Master Slave Master Slave Macher Slave ALARMS with seme color must have identical RP type 5506 and security settings Wireless Bridge mode can also connect wireless clients to another SSID as show
20. 11 Access Points APs and provide access to the mesh network to 802 11 stations STAs which have broad market availability Also mesh STAs can collocate with an 802 11 portal that implements the role of a gateway and provides access to one or more non 802 11 network In both cases 802 11s provides a proxy mechanism to provide addressing support for non mesh 802 devices allowing end points to be cognizant of external addresses 802 11s also includes mechanisms to provide deterministic network access congestion control and power saving Table 802 11 Standards and Date Rate Release Wig est Range Typical Range Prot M KIK STI outdoor 802 11 1997 2 4 2 5 GHz 2 Mbps 5 15 5 35 5 47 5 725 802 11a 1999 5 725 5 875 GHz 54 Mbps 30m xm soiDoJouuoe SSajJAUIM ueeAgeg Punenuoeioeyiq T 802 11b 1999 2 4 2 5 GHz 11 Mbps 30m 100 m 802 11g 2003 2 4 2 5 GHz 54 Mbps 30 m 100 m 802 11n 2008 2 4 GHz or 5 GHz bands 600 Mbps 50m 125m WWW moxa com info moxa com 8 Differentiating Between Wireless Technologies o 1 4 WLAN vs Proprietary 2 4GHz Common usage of the WLAN limits its distance to under 100 meters Now with Moxa s advanced technologies it is also possible to extend the distance up to 10 kilometers for multi point connections or 20 kilometers for point to point connections The IEEE 802 11 standard is designed for high speed data transmission However it is also vulnerable to outside interferences This is unacceptable f
21. 11a has 12 parallel channels among them 8 of which are used for indoor communications and 4 for point to point communications IEEE 802 11b is not inter operable with IEEE 802 11a unless the communication devices support both standards IEEE 802 11a has the advantage of less interference than IEEE 802 11b as IEEE 802 11b s 2 4 GHz band is widely used However the high frequency also has some downsides IEEE 802 11a has a much narrower coverage so it needs more access points This also means that signals can not be transmitted as far as IEEE 802 11b because it is much easier for signals to be absorbed by surrounding objects Parameter Tuning Wireless devices have traditionally been limited in range due to the inherent design of the 802 11 standard 802 11 protocol uses acknowledge for each received frame If an acknowledgement is not received the frame is re transmitted By default the maximum distance between transmitter and receiver is 1 mile 1 6 km On longer distances the delay will force retransmissions so Moxa has tuned our Wireless product to support long range deployments using wireless 802 11 Moxa Wireless Products are now enhanced with the ability to automatically adjust parameters such as slot time ACK time out and CTS time out to fine tune the wireless device for optimal performance and achieve a longer range Environmental Conditions Two factors are considered as below e 2 4GHz interference There are literally hundreds
22. 2 11 9 UNII Band The 5 GHz UNII band consists of 3 parts each 100 MHz wide The 802 11a standard uses this band Each part of the UNII band includes 4 non overlapping channels with 5 MHz of guard band between them The FCC states that the lower band UNII 1 can only be used indoors the middle band UNII 2 can be used indoors or outdoors and the higher band UNII 3 should only be used outdoors Since UNII 1 and UNII 2 can be used indoors the maximum number of non overlapping channels in an indoor environment is 8 See below for channels supported in the 5 GHz UNII band for different countries Channel ID Frequency MHz UA EU M East Asia 36 V V 5180 V 40 5200 V V V 44 5220 V V V 48 5240 V V V 52 5260 V V V 56 5280 V V V 60 5300 V V V 64 5320 V V V 100 5500 V V V 104 5520 V V V 108 5540 V V V 112 5560 V V V 116 5580 V V V 120 5600 V V V 124 5620 V V V 128 5640 V V V 132 5660 V V V 136 5680 V V V 140 5 00 V V V 149 5745 V 153 5 65 V 157 5 85 V 161 5805 V 165 5825 V t Signal Power Radio signals are transmitted with a certain power level Power is measured in watts However a watt is a rather large amount of power in WLAN Therefore power is usually measured in milliwatts mW which is one thousandth of a watt A typical wireless AP transmits between 30 to 100 mW of power and about 50 mW for wireless adaptors clients Certain applications will require higher transmit Tx power and may attempt to use power booster
23. AGVanced 2009 Industrial Wireless Guidebook 4 Your Guide to Industrial Wireless WWw w moxa com Preface Wireless technologies have become increasingly popular in industrial automation as growing numbers of system integrators governmental agencies and industrial solution providers continue to turn to these solutions for their applications Advantages of using wireless technologies include boosting data transmission speed real time data transmissions remote equipment monitoring and alerts flexible installation of remote equipment and wide coverage areas In addition wireless technologies can penetrate areas where cables are unable to reach saving wiring costs By adopting wireless technologies industrial applications are able to benefit from greater versatility However the completeness of data security of transmission and reliability of the wireless network are constant concerns as wireless technologies rely completely on the emission of electromagnetic waves through the air Drawing from over 20 years of experience Moxa offers users the most reliable industrial networking solutions including Turbo Roaming for seamless wireless communication as well as extended wireless transmission ranges of over 10 km In addition our complete selection of products for demanding industrial environments includes wide temperature 40 to 75 C models IP67 rated protection from water and dust and EN50155 ce
24. C IP65 3 260 mm length 155 g ANT WDB PNF 1518 E Plane 2 4 GHz at Phe nc LC AT TETE T E E CH P m Pw Pm m A 2 4 to 2 5 5 1 to 5 9 GHz Directional Panel 15 18 dBi 50 5 ohms Linear 50 10 30 10 1 1 5 Max 20 W Max N type female 40 to 80 C IP65 270 x 205 x 15 mm 1020 g NE 7 WWW moxa com infogmoxa com 2009 Industrial Wireless Guidebook IEEE 802 11a 5 GHz Wireless Antennas ANT WSB5 ANF 12 ANT WSB5 PNF 18 E Plane w wA TEML T mu m mim Mt Directional Panel 1 1 3 Max 1 1 5 Max e Handlini 10 W Max 10 W Max N type female N type female E AT 40 to 80 C 40 to 80 C IP65 IP65 i nna Profi 420 mm length 270 x 205 x 15 mm 430 g 990 g s La pur a S m ie m R ee Pe 3 2 MS PALL a m 02 IT T1 umm ur TE S S ee a a C 5 Q D zj T et e 2 a 5 e gt Q m et 3 m Z I m m m 00 e NO za WWW moxa com info moxa com 2 M Understanding Industrial WLAN IEEE 802 11 o Cellular Antennas UMTS HSDPA WCDMA Cellular Antennas ANT CQB ANT CQB ANT CQB ANT CQB ANT WCDMA ANT WCDMA ASM 01 AHSM 00 3m AHSM 03 3m AHSM 05 3m ASM 1 5 AHSM 04 2 5m GSM GPRS Cellular Antennas 850 900 850 900 850 900 850 900 850 900 1800 850 900 1800 1 KA 900 MHz 1800 1900 MHz 1800 1900 MHz 1800 1900 MHz 1 MAN 00 MHz 1900 2100 MHz Cable Type p
25. Graphics HMI e Alarms e Trends and Process Analyst e Commands and Controls SCADA usually refers to centralized systems that monitor and control entire sites or a network of systems spread out over large areas Most control actions are performed automatically by intelligent I O devices i e Moxa s Active Ethernet I O remote terminal units RTUs or programmable logic controllers PLCs Host control functions are usually restricted to basic overriding or supervisory level intervention For example a PLC may control the flow of cooling water through part of an industrial process but the SCADA system may allow operators to change the setpoints for the flow and enable alarm conditions such as loss of flow and high temperature to be displayed and recorded The feedback control loop passes through the Active Ethernet I O or RTU or PLC while the SCADA system monitors the overall performance of the loop Modem Extension Mode Virtual Modem Data acquisition begins at the RTU PLC or I O device level and includes meter readings and equipment status reports that are communicated to the SCADA system as required Data is then compiled and formatted in such a way that a control room operator using the HMI can make supervisory decisions to adjust or override normal I O controls An HMI is usually linked to the SCADA system s database and software programs to provide trending diagnostic data and management information such as scheduled maintenanc
26. P address DHCP local address pool RADIUS When the MS opens PDP context GGSN assigns an address to the MS Obtaining an IP Address From a local address pool on the GGSN Via DHCP Via RADIUS from an external RADIUS server From the customer s network via an L2TP tunnel from the GGSN WWW moxa com infogmoxa com 2009 Industrial Wireless Guidebook 3 2 Private IP Solution There are two limiting factors you are almost assured to encounter when setting up a wired LAN with private IP addresses in an office 1 short transmit latency and 2 limited IP addresses to connect to the Internet for the cellular WAN interface As a result delay times for the WAN interface are very different from the local area network s delay times WAN port IP addresses are also very different from those in office LANs i Private IP vs Public IP From the LAN point of view According to RFC 1918 standards office networks are allocated private IP addresses according to class A B and C The Internet Assigned Numbers Authority IANA has reserved the following three blocks of IP address space for private networks 10 0 0 0 10 255 255 255 10 8 prefix 172 16 0 0 172 831 255 255 172 16 12 prefix 192 168 0 0 192 168 255 255 192 168 16 prefix From the cellular WAN port point of view Normally IP addresses for cellular WAN ports will have Type of Address Role s of Configured Devices Mobile operator keeps a pool of
27. P capability to reach IP Internet domains offer a viable solution that reduces loading for serial devices so they can focus on transmitting and receiving serial data Cellular networks are everywhere so you can make calls without a wired telephone connection providing industrial automation machine to machine applications with additional benefits IP Gateways IP gateways are not only call setup intelligent but also come with built in TCP IP capability Due to the popularity of cellular networks around the world you will be able to use them to communicate from just about anywhere Moreover IP gateways can help your serial devices transfer and receive data conveniently Moxa s cellular IP gateways solution offers flexible communication for serial devices 1 How OnCell Cellular IP gateways can help your serial device access an IP domain E e Keep existing software Real COM Reverse Real COM e Standard TCP IP connection TCP server Client e Real time serial data send receive solution e Short message connection SMS Tunnel Network capabilities for data bearer e IP gateways over CSD e IP gateways over GPRS Keep Existing Software Real COM Reverse Real COM Moxa s Real COM and Reverse Real COM operation modes are used to link remote serial devices to the control center By simply installing OnCell Driver Manager onto a host computer at the control center your applications will be able to keep existing serial interface soft
28. R and user profiles e g IMSI ID code of the SIM card addresses used in the packet data network of all GPRS users registered with a particular SGSN e Gateway GPRS Support Node GGSN The Gateway GPRS Support Node GGSN is a main component of GPRS networks The GGSN is responsible for connecting the GPRS network to external packet switched networks such as the Internet and X 25 networks The GGSN stores the current SGSN address of the user and his or her profile in its location register The GGSN is responsible for IP address assignment and is the default router for the connected user equipment UE The GGSN also performs authentication and charging functions Other functions include subscriber screening IP Pool management and address mapping QoS and PDP context enforcement SXJOM 9N JeJNIj2D Sg ii op vm f 3 A ses A pss ant circu sate 5 d e Summary General Packet Radio Service GPRS Connectionless Bill by packets IP based communication Internet access and increasing speed with 3G HSDPA HSUPA etc WWW moxa com infogmoxa com 46 47 Cellular Networks DJ t APN in Packet Switch Each external network is given a unique Access Point Name APN that is used by the mobile user to establish the ugs connection to the required destination network U BSS SGSN 1 Activate POP Context Riequast APM QoS 2 Create POP context request IP address Create POP c
29. able to perform multiplatform monitoring event management alerting real time performance monitoring network discovery and topology mapping Centralized Management More advanced network management tools provide a complete solution for network administrators including VPN firewall and UTM It also allows centralized management for device maintenance 41 WWW moxa com info moxa com 2009 Industrial Wireless Guidebook 2 7 Industrial Certification i EN50155 Certification EN50155 are the standards that define requirements for railway cars or rolling stock It clearly outlines the requirements for power input voltage fluctuation transient ambient temperature ranges shock and vibration and as well as fog and salt spray Electronics that are used aboard railway rolling stock are required to meet the standards of EN50155 The target of EN50155 certification for all electronics is for the devices to be operable 24 7 for as long as 20 years To meet this standard an electronic device needs to meet the requirements as summarized below Power Input Voltage Fluctuation A nominal 110 VDC power input system needs have at least 77 to 137 5 VDC voltage fluctuation range with no time limits The fluctuation may sometimes become too extreme so electronic devices should also be able to withstand 66 to 154 VDC power input for at least 100 ms Transient and Ambient Temperature Railway rolling stock require an operating tem
30. and over and roaming Cellular networks are connected to the PSTN to give transparent incoming and outgoing access to fixed network subscribers The following diagram shows a typical GSM cellular network architecture Network and Switching Subsystem NSS Parts MSC Mobile Switch Controller GMSC Gateway MSC HLA Home Location Register VLR Visitor Location Register AuC Authentication Center EIR Equipment Identity Register Base Stalion Subsystem BSS Mobile Station MS Parts Supports the switching Parts Base Transceiver Station BTS functions subscriber profiles Mobile Eguipment ME Base Station Controller BSC and mobility management Subscriber Identity Module SIM e Radio Interface Connects to MS Moxa OnCell G2100 3100 series PDA or PC e A Interface Connects to connected to the ME MSC i Data Service of GSM Here we show how to implement these three data services We hope this will help you understand how these technologies work so you can select the most suitable application WWW moxa com info moxa com SX4JOMJ 9N JE NIJSDO E 44 Cellular Networks gt Short Message Services SMS SMS messages as specified by the ETSI organization documents GSM 03 40 and GSM 03 38 and can be up to 160 characters long where each character is 7 bits according to the 7 bit default alphabet Eight bit messages max 140 characters are usually not viewable on phones as text messag
31. and the ability to stay connected in high speed movement To satisfy the need for data exchange over cellular networks 3G networks were developed to improve spectral efficiency The improvements incorporate voice video and broadband wireless data transmission all in the mobile environment The most commonly seen 3G systems are the Universal Mobile Telecommunication Systems UMTS and the Wideband Code Division Multiple Access WCDMA These 3G systems are the major revenue contributors to carriers in the past three to two years As the technologies continue to evolve transmission speeds have become faster For example High Speed Packet Access HSPA offers downlink speeds that can reach 144 Mbps and 5 8 Mbps for the uplink It is not wonder the building of 3G facilities and networks are on the rise Worldwide subscribers are expected to increase rapidly over the next 3 to 4 years However 4G technologies are already in the works and aim to take mobile data transmission to an even higher level HSDPA High Speed Downlink Packet Access HSDPA or 3 5G is a mobile telephony communications protocol It provides packet data service in WCDMA downlink The transmission speed can reach 8 10 Mbps on a 5 MHz carrier wave and 20 Mbps with MIMO technology In practice the technologies deployed include AMC MIMO HARG fast scheduling and fast cell selection HSUPA High Speed Uplink Packet Access HSUPA or 3 75G was developed in response to the inad
32. ansmission t Limitations of High Speed Roaming The first limitation of the Threshold based Handover Algorithm is wireless resource consumption because the client is constantly scanning for APs that also need to respond in due time To solve this problem the network topology and system configuration needs to be carried out in greater detail The second limitation is that there is currently no unified high speed roaming standard so roaming among different APs from different manufacturers might not be possible WWW moxa com info moxa com 2009 Industrial Wireless Guidebook 1 Roaming Speed Acceleration To increase the roaming speed a common method is to use the Threshold based Handover Algorithm The Threshold based Handover Algorithm allows roaming only when the current AP s signal drops below a certain threshold so that roaming to another AP would improve the transmission quality and at the same time provide a stronger signal In short the Threshold based Handover Algorithm means the client will constantly scan for the best AP signal quality and roam only when the threshold is reached This can prevent the ping pong effect unnecessary handovers that might take place when the client moves back and forth between two APs Also this can increase the roaming speed to deliver a smoother data transmission The second way to increase the roaming speed is to unify AP channels to avoid wasting channel hopping time during roaming How
33. aru 74 U poru 74 U ORGITA 74 U RG174 U Impedance 50 S0ohms 50 S0ohms 50 S0chms 50 S0ohms 50 Soms 50 ohms ont 3 SMA M SMA M SMA M SMA M SMA M SMA M Antenna Profile 3 3 mm length 100 mm length 250 mm length 370 mm length 104 mm length 110mm length ces 3m 3m 3m 2 5 M WWW moxa com info moxa com 2009 Industrial Wireless Guidebook Moxa Performance Test Report ANT WDB O 2 Omni dipole dual band 2dBi antenna istant oa oe NECK 1 2 4G AP Station Mbps 18 38 16 62 7 869 4 471 2 4G Station gt AP Mbps 20 13 17471 6 82 4 008 SG AP gt Station Mbps 20 371 0 4725 12 959 N A 5G Station AP Mbps 19 0608 13 637 13123 MNA N A Not Available ANT WSB ANM 05 Omni dipole 2 4G 5dBi antenna Distance Km 2 4G AP gt Station Mbps 24 257 24G Station AP Mbps 20 67 N A Not Available 2 ANT WSB ANF 09 Omni directional 2 4G 9dBi antenna Distance Km 2 4G AP gt Station Mbps 18 725 17 557 2 4G Station gt AP Mbps 20 452 19 953 N A Not Available ANT WSB5 ANF 12 Omni directional 5G 12dBi antenna Distance Km 5G AP gt Station Mbps 5G Station gt AP Mbps N A Not Available ANT WSB PNF 12 Uni directional 2 4G 12dBi antenna Distance Km 2 4G AP gt Station Mbps 2 4G Station gt AP Mbps N A Not Available ANT WDB PNF 1518 Uni directional dual band 15 18 dBi ante
34. at is much wider than the minimum bandwidth required by the information signal The transmitter spreads the energy originally concentrated in narrowband across a number of frequency band channels on a wider electromagnetic spectrum Some of the advantages include M Useri MM User 2 b 7 us E v DT Improved privacy Decreased narrowband interference Increased signal capacity Time slot WWW moxa com infogmoxa com 2009 Industrial Wireless Guidebook DSSS Direct Sequence Spread Spectrum DSSS divides a stream of information to be transmitted into small pieces each of which is allocated to a frequency channel across the spectrum DSSS generates a redundant bit pattern for each bit to be transmitted This bit pattern is called a chip or chipping code Even if one or more bits in the chip are damaged during transmission statistical techniques embedded in the radio can recover the original data without the need for retransmission Direct sequence spread spectrum is also known as direct sequence code division multiple access DS CDMA This modulation technique is officially accepted and used by the IEEE 802 11b and IEEE 802 11g standards Signal Level Channel 2 Channel 6 Channel 10 2400 2412 2417 2422 2427 2432 2437 2442 2447 2452 2457 2462 2467 2472 2477 Frequency 9 10 11 12 13 14 MHz OFDM Orthogonal Frequency Division Multiplexing OFDM is a modulation scheme that divides a single digital
35. ble there are also task groups within IEEE designated to develop different wireless applications IEEE 802 11 IEEE 802 11a IEEE 802 11b IEEE 802 11c IEEE 802 11d IEEE 802 11e IEEE 802 11f IEEE 802 119 IEEE 802 11h IEEE 802 11i IEEE 802 11 IEEE 802 111 IEEE 802 11m IEEE 802 11n IEEE 802 11 k IEEE 802 11r IEEE 802 11s 1 WWW moxa com 2 Mbps 2 4 GHz band 1997 MAC Physical Standard 54 Mbps 5 GHz band 1999 MAC Physical Standard 11 Mbps 2 4 GHz Band 1999 MAC Physical Standard MAC Layer Bridging to support IEEE802 1D Automatic settings for different countries Quality of Service QoS IAPP Inter Access Point Protocol cancelled by IEEE after February 2006 54 Mbps 2 4 GHz Band 2003 MAC Physical Standard Support more channels on 5GHz spectrum 2004 Wireless security 2004 Japanese Standard upgrade 2004 Reversed Maintenance Standard Draft now using MIMO Multi input Multi Output Technology to increase transmission speed to 300 600Mbps Define measurement items and protocol Define implementations of WLAN roaming enables 802 11 able to be applied to mobile and VoIP applications Standard for Mesh under standard architecture infogmoxa com 2009 Industrial Wireless Guidebook i IEEE 802 11n In January 2004 IEEE made an announcement to form a new task force to develop new standards for the IEEE 802 11 standard The goal of this task force was to allow wireless
36. cation server also takes responsibility for computing the keys that the encryption algorithm Will use Although the details of authentication may be complex the overall procedure is easy to describe STEP 1 The Authenticator relays authentication messages between the WLAN and the Ethernet STEP 2 The Authentication Server and Supplicant establish a secure tunnel that is used to pass encrypted messages STEP 3 The Authenticator performs the authentication check based on the agreed upon method TLS PEAP MSCHAP V2 TTL etc WWW moxa com info moxa com 18 Understanding Industrial WLAN IEEE 802 11 amp 3 Encryption The science of encryption or in more down to earth terms the making and breaking of codes is one of the most crucial aspects of WLAN technology This is because the radio waves used to transmit data packets between your computer and the wireless access point can pass through walls floors and other barriers People who use laptops that have a wireless LAN card will know this first hand since it is often possible to pick up signals from wireless access points located in nearby apartments Using a password to restrict entry to your network may not provide enough protection since a reasonably clever person can still intercept your data packets In fact if the person intercepting the wireless data is more than reasonably clever he or she may also be able to download and read the contents of the packets As illust
37. d grouping and for the GPRS world the VPN grouping concept solves the dynamic IP address issues The grouping of the devices into one private network prevents unauthorized persons from accessing the data For this VPN solution customers are required to buy a number of different GPRS on line services and to apply for access to a Virtual Private Network VPN When the GPRS device dials up the carrier will assign a private IP address to it and because the private IP address is on the same network segment as the host the host and devices can maintain bi directional communication using a polling architecture Solution 3 DDNS Using dynamic IP addresses is often necessary since many ISPs do not provide static IP addresses or because the cost of obtaining a static IP address is too expensive The Dynamic Domain Name System DDNS is used to convert a device s name into a dynamic IP address so that remote devices can communicate with the control center using a fixed domain name When GPRS devices get an IP from the carrier they will automatically connect to the GPRS network Each time a GPRS device s built in DDNS client gets a new IP address it will send the IP address to the DDNS sever The mapping table in the DDNS server is refreshed each time the DDNS receives a new IP address from the devices WWW moxa com info moxa com 66 Cellular Networks o New Push Architecture for GPRS Networks Push Architecture is a mobile centric solution
38. dth with you Our discussion only includes the 2 4 GHz ISM band and 5 GHz UNII band because these 2 frequency bands are the most commonly used in WLAN applications 13 WWW moxa com infogmoxa com 2009 Industrial Wireless Guidebook 2 4 GHz ISM Band As 802 11b g is the most commonly used WLAN standard today the 2 4 GHz ISM band is supported by almost every country worldwide Not every country supports the same channels in the 2 4 GHz ISM band so you need to make sure the wireless AP matches the standard used by your country The following chart shows channels supported in the 2 4 GHz ISM band for different countries continents Channel Number Center Frequency USA EU M East Asia M M 2 412 an 39 ae H AAA AAA A a T OOO OOO Ia ap eae v XY ok Woo 00 24 0000 Y 000 Y 00 aa naaa 14 2 484 Y DSSS only The FCC opened the frequency band between 2 4 to 2 5 GHz and the IEEE uses 2 400 to 2 4835 GHz The minor mismatch is to provide a buffer to prevent power from leaking into the forbidden band lt lt lt lt lt lt lt lt lt lt CO N Oo GI RK C DY lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt lt c O D o RV Q 3 Q o I m ITI m Qo N WWW moxa com info moxa com 14 Understanding Industrial WLAN IEEE 80
39. e Click amp Go logic inside Rich Alarm functions SMS SNMP trap and e mail Lower bandwidth consumption push architecture reduces bandwidth by 8096 compared to the polling architecture Faster response time because of push technology and event handling Data Logging Local data logged to SD card and pushed to host by TFTP i Conclusion Remote monitoring and alarm systems used in water distribution pipeline management and environmental monitoring applications must be capable of covering a wide area and function reliably Most importantly the cost must be affordable A remote monitoring and alarm solution with Moxa s Active GPRS I O devices and Active OPC Server help users overcome the frustrations associated with using dynamic IP addresses and makes it extremely easy to connect to SCADA systems SX4JOMJ 9N JeJNI 2D E Reference 1 http en wikipedia org wiki SCADA 2 http www citect com index php option com content amp viewz article amp id 1502 amp ltemid 1366 3 How to put SCADA on the Internet http www controleng com article CA321065 htmi 4 OPC amp DCOM 5 Things You Need to Know www opcti com WWW moxa com info moxa com 68 Creating Excellence Since 1987 MOXA About Moxa For more than twenty years industrial systems integrators have relied on Moxa products in major device networking installations around the world Moxa offers industrial grade solutions backed by an excellent warrant
40. e Keying 6 OFDM BPSK ES poss Deck C BPSK Bi phase Shift Keying 2 DSSS QPSK DSSS C BPSK t ISM and Licensed Band The FCC Federal Communications Commission regulates the usable freguency bands and the maximum allowable power in these freguency bands for the United States WLAN devices are allowed to use the ISM Industrial Scientific Medical band by the FCC The ISM band consists of 3 different sub bands 902 MHz 2 4 GHz and 5 8 GHz The FCC has also further defined the UNII Unlicensed National Information Infrastructure band for WLAN usage The following diagram shows the spectrum overview of the ISM and UNII bands A ati Figure ISM and UMI Bands IEEE 4 FCC 5 18 amp 25 5725 Ecc T 24000 2 5000 GHz LIT 2400 2425 2480 2475 2500 5 000 5 t Tm 6 000 Guz GHE a Fog 8728 5 AT8 GHz 151 FCC 902 528MHz 1 900 3910 920 0830 MHz 8 728 8 778 5 825 8 878 GHz TTE Raap Mees u Research div ign nar Mu 10 Hn 1 10 MHz MHz GHz GHz Advantages and Disadvantages of Using Unlicensed Bands ISM and UNII are both un licensed bands which means anyone can transmit in these bands without a license from the FCC It is the opening of these un licensed bands that has allowed the WLAN business to grow in small businesses and homes The freedom of these license free bands also means a great number of un licensed users may share the bandwi
41. e of the Ethernet device from TCP Server to TCP Client Now the OnCell device is a gateway for the TCP Client to route its traffic to the public domain through the cellular network The NAT function built into the OnCell device allows the WAN and LAN interfaces to direct traffic to each other The Ethernet device can now locate the server on the public domain to establish a remote connection For example multiple Ethernet devices at a remote site can act as TCP clients and all connect to the same server in the control center for central management When the OnCell is acting as a client its WAN IP address will not be limited to public WAN IP addresses The WAN IP address of the OnCell IP modem can be public or private static or dynamic without any extra settings How to configure the OnCell as a gateway to the public domain For the OnCell G3100 series you do not need to perform extra settings to use the OnCell as a gateway for connected Ethernet devices to be able to access the public internet The built in NAT function is enabled by default so by simply setting the default gateway IP address of the Ethernet device to the OnCell s LAN IP address the Ethernet device will be able to connect to the Internet and initiate TCP connection requests to the TCP server SXJOM 9N JeJNIj2D E Please note that if you are going to be accessing a domain name on the Internet not only do you need to set the OnCell as your default gateway but a public DNS server
42. e procedures logistic information detailed schematics for a particular sensor or machine and expert system troubleshooting guides Data may also be fed to a commodity database to allow trending and other analytical auditing SCADA systems typically implement a distributed database commonly referred to as a tag database which contains data elements called tags or points A point represents a single input or output value monitored or controlled by the system Points can be either hard or soft A hard point represents an actual input or output within the system while a soft point results from logic and math operations applied to other points Most implementations conceptually remove the distinction by making every property a soft point expression which may in the simplest case equal a single hard point Points are normally stored as value timestamp pairs a value and the timestamp when it was recorded or calculated A series of value timestamp pairs gives the history of that point It s also common to store additional metadata with tags such as the path to a field device or PLC register design time comments and alarm information 59 WWW moxa com info moxa com 2009 Industrial Wireless Guidebook The SCADA system reads the measured flow and level and sends the setpoints to the PLCs row Mete water T PLC2 compares the measured level to the setpoint controls the flow through the valve to match level to setpoin
43. e wireless to replace traditional wired solutions to transmit larger data such as video NOTE WLAN technologies are discussed in detail Chapter 2 WWW moxa com info moxa com 7 2009 Industrial Wireless Guidebook i WPAN Wireless Personal Area Network A WPAN is a short range peer to peer or ad hoc network built around a person s working area Normally the distance is no more than 10 meters Because of their limited transmission range WPANs are used mainly as cable replacement solutions for data synchronization and data transmission for personal electronic devices such as PDAs or smart phones Bluetooth is the most prevalent WPAN technology in use today It allows devices such as phones mice headsets and other personal devices to connect wirelessly within a range of 10 meters The shorter communication distances also mean lower power consumption making Bluetooth an even more ideal solution for short range data transmission Moxa will be releasing WPAN products in 2010 Wireless Network Coverage 1 2 Evolution of Cellular Networks t 3G Technologies 3G refers to the third generation of telecommunication technologies that is designed to replace 2 5G GPRS or CDMA The demand for 3G comes from the growing need for data transmission over wireless networks The features of cellular networks make them particularly attractive to wireless users in comparison to IEEE 802 11 standards Cellular has the advantages of wider coverage
44. ectivity requests Another way is to set up a virtual server that allows remote users to access the Host or FTP services via a public IP address and automatically redirects them to local servers in the LAN This firewall feature will filter out any unrecognized packet to protect your LAN WWW moxa com info moxa com 50 51 Cellular Networks o 3 4 How to Connect Serial Devices to Cellular Networks i Traditional Modems Serial port connections are very popular in traditional industrial applications but their transmission distance is limited The Hayes command modem AT command offers a good solution for enlarging the transmission distance It connects two serial devices through PSTN via an AT modem This traditional modem always occupies the line as a voice call so even when you are not talking transmitting data you will still be charged by the minute for staying on the line In addition the serial device such as a PLC link to the modem needs dial up capability for call controls such as dialing a number checking if the called side is busy retrying the call and hanging up If the connected link is an IP domain then the serial device needs built in PPP Point to Point Protocol capability to access the IP domain whether it is an Internet or VPN Serial devices also require many call control capabilities in order to link to traditional modems resulting in heavy loading IP modems eguipped with call setup and PP
45. efore be applied to finance medicine education transportation and other industries This is because the communication terminal is able to manage more tasks such as multimedia communications remote control and voice communications If area networks Internet telecommunications radio broadcasts and satellites are grouped together as an integrated network in the future regardless of the terminal used they will be able to offer complete wireless and broadband connectivity and higher quality service Such advancement would allow 4G technologies to penetrate every aspect of our lives From the subscribers perspective 4G is able to provide faster speed and satisfy more needs The fundamental driving force of moving mobile communications from analog to digitalization and from 2G to 4G is the shift from wireless voice service to wireless multimedia service in subscriber needs This has spurred operators to adapt because they need to boost ARPU develop new frequencies to attract more subscribers design more efficient spectrum use and cut their operational costs In effect 4G involves two different but overlapping concepts e High speed mobile telephony system with speed as fast as ADSL s bandwidth 10 Mbps or higher This concept formerly applied to wireless technologies such as Wi Fi It is also the vision addressed by the successful 3G system providers presently e Pervasive network technology a more abstract term often defined as wireless
46. eless Guidebook 3 3 Security One of the major concerns faced by system integrators when adopting an Ethernet solution is the security and confidentiality of data transmissions over the network Wireless networks are especially vulnerable because they need to transmit data through open air and are vulnerable to sniffing To protect the security of wireless connections one of the most commonly seen solutions is the VPN i k The Virtual Private Network VPN A VPN is a computer network that links up two or more networks or nodes by using open connections or virtual circuits Many people believe that a VPN offers sufficient data transmission security However a VPN by itself does not guarantee information security In response to the lack of security when tunneling through the network L2TP and IPSec are often used to enhance network security Layer 2 Tunneling Protocol L2TP is a tunneling protocol used in a VPN L2TP is sent in a UDP datagram It contains no security feature on its own so it is often implemented along with IPSec IPSec is an open communication standard created to ensure data transmission security over public networks IPSec is also a Layer 4 security protocol which is the most widely used way to ensure security for it is a more balanced solution than Layer 1 and Layer 7 security control IPSec uses either Authentication Header AH or Encapsulating Security Payload ESP AH can protect packet headers and data in
47. ennas Selection Guide 30 IEEE 802 11b g 2 4 GHz Wireless Antennas EEE 802 11a b g 2 4 5 GHz Dual band Antennas EEE 802 11a 5 GHz Wireless Antennas Cellular Antennas Setting Up Point to Point Connections Antenna Alignment for P2P Operations Moxa Performance Test Report 2 5 Mobile Optimization 39 Roaming Under Linear Movement Roaming Speed Acceleration Limitations of High Speed Roaming 2 6 Advanced WLAN Technologies 37 Dual RF Redundancy Mesh Technologies Wireless VLAN QoS for Video Audio and Control Wireless Management 2 7 Industrial Certification 42 EN50155 Certification ATEX Class Division 2 2009 Industrial Wireless Guidebook Chapter3 NV NEN Cellular Networks 3 1 Cellular Basics 44 Data Service of GSM APN in Packet Switch 3 2 Private IP Solution 48 Private IP vs Public IP Delay Time Solution for Private IP Moxa OnCell Central Manager 3 3 Security 50 The Virtual Private Network VPN Firewall 3 4 How to Connect Serial Devices to Cellular Networks 51 Traditional Modems P Gateways 3 5 How to Connect Ethernet Devices to Cellular Networks 56 From WAN to LAN TCP Server From LAN to WAN The OnCe
48. equate upload speed of HSDPA only 384 Kbps The transmission speed can reach 10 15 Mbps on a 5MHz carrier wave 28 Mbps with MIMO technology The upload speed goes up to 5 76 Mbps 11 5 Mbps with 3GPP Rel7 technology With HSUPA functions requiring massive upload bandwidth e g two way live transmission or VoIP can be realized soiDoJouuoe SSaJAUIM ueeAgeg Hulenuseyjig E WWW moxa com info moxa com 4 Differentiating Between Wireless Technologies o amp CDMA2000 1xEV Evolution CDMA2000 1xEV is CDMA2000 1x equipped with HDR 1xEV in general has two sessions e CDMA2000 1xEV 1st session CDMA2000 1xEV DO in light of the fast data transmitted under a wireless channel supports downlink data speeds up to 3 1 Mbps with uplink up to 1 8 Mbps e CDMA2000 1xEV 2nd session CDMA2000 1xEV DV Evolution Data and Voice supports downlink data speeds up to 3 1 Mbps with uplink up to 1 8 Mbps 1xEV DV also supports 1x voice subscribers 1xRTT data subscribers and high speed 1xEV DV data subscribers to use the same wireless channel at the same time 2G 36 4G L mmi SM mm ee gt arns ma EDGE ma WCDMA i 4G Technologies Fourth generation technologies made their market debut in 2009 The goal of 4G is to increase downlink speed to 100 Mbps and uplink speed to 50 Mbps The two major competing technologies in the 4G market are Long Term Evolution LTE and WiMax sponsored by the IEEE Group Possible 4G Standa
49. er to allow clients to make a direct TCP connection to it before forwarding traffic to the actual server Much like a WLAN router the traffic from the WAN port is directed to the devices connected to the LAN port of the router It is important to note that your OnCell device will need to obtain a public WAN IP address from your cellular provider in order for it to be visible to the public domain Private IP addresses are hidden from the public Internet so TCP Clients will not be able to find it on a public network The WAN IP address of your OnCell device may be static or dynamic but it must be a public IP address If the public WAN IP address is a dynamic IP address changes every time the OnCell reconnects to the cellular network a useful function is to enable to DDNS Dynamic DNS DDNS allows the TCP clients to access the OnCell device by domain name So even as the OnCell device s WAN IP address changes the changed IP addresses continue to map to the same domain name through DDNS updates In cases where only private IP addresses are available from the cellular provider the OnCell can still play the server role by enabling the OnCell Central Manager see section 3 2 for details function proprietary to Moxa s IP gateways WWW moxa com info moxa com 56 Cellular Networks o How to configure the OnCell device as a virtual server In the OnCell device s web console you will find a virtual server settings page where you can set up multiple
50. ervice providers commonly referred to as carriers often assign temporary IP addresses to their clients to access the Internet Compared with static IP addresses using dynamic IP addresses make it difficult for the control centers to keep in constant contact with remote devices The Traditional Polling Architecture of GPRS Networks Traditional monitoring and alarm systems use a polling architecture that will only work properly if the host knows the IP addresses of the I O devices used by the system The trouble with I O devices with GPRS capability is that the devices receive a different IP address every time they connect to the GPRS network Three distinct solutions have been developed to tackle this obstacle Solution 1 Public Static IP Address The first choice is to get a public static IP address some carriers can assign a static IP address to a specific SIM card This way all the I O devices will have their own static IP address and the entire system will operate in the same manner as a traditional monitoring system that uses physical wiring Perhaps the main benefit of this solution is that it behaves the same as a wired solution However not all carriers offer this kind of service and when they do the cost is relatively high SX4JOMJ 9N JeJNI 2D E Solution 2 VPN Service Provided by Carrier MVNO A VPN Virtual Private Network is a secure LAN solution that groups specific devices together VPN has two major functions security an
51. es Instead they are used for data in 16 bit messages max 70 characters and used for Unicode UCS2 text messages viewable on most phones SMS is a point to point store and forward technology with 2 basic functions e Transmit a message from the short message service center to the mobile station SMS DELIVER PDU Protocol Data Unit e Transmit a message from the mobile station to the service center SMS SUBMIT PDU Protocol Data Unit SMS messages contain up to 140 octets which is equivalent to e 160 Latin characters 7 Bit Coding in Text Mode or e 70 Unicode characters double byte such as Arabic or Chinese characters SMS Summary e Up to 140 octets or 160 characters for every message e No IP based communication only suitable for sending receiving serial data Circuit Switch Data CSD Circuit Switched Data CSD is the original form of data transmission developed for Time Division Multiple Access TDMA based mobile phone systems like Global System for Mobile Communications GSM GSM CSD bearer service is the most widely used data service providing a non transparent data rate of 9 6 Kbps Non transparent in this context means error correction and flow control Usually GSM network operators support the non transparent CSD bearer service through a modem interworking function This means that a mobile station mobile phone initiates a data call and the network routes the call to the modem interworking function which is loca
52. es authentication to check a user s credentials and determine if the user should be given access to the data and resources provided by the protected network Encryption on the other hand encodes the data so that anyone who does not have the secret key will not be able to read the data E Authentication The 802 1X standard dictates how authentication on wired and wireless LANs is carried out 802 1X authentication uses port based access control which means that the various entities involved in the authentication process gain access to each other s resources by connecting through ports In effect the authentication procedure involves placing a guard at each port to prevent unauthorized users from gaining access to protected data The 802 1X authentication procedure involves three basic players e The supplicant is the client PC or laptop computer for example who would like to gain access to network resources through the wireless network e The authenticator which is usually an access point AP for a LL 208 333l NV 1M Ieuisnpuj Guipuejsaepur wireless network plays the role of plici gatekeeper pem SN XM e The authentication server oe walen connects to the AP over a T a wired network handles the nd authentication procedure More often than not a RADIUS server is used In effect the authenticator and authentication server work as a team to verify the identity of the supplicant The authenti
53. ever a unified channel selection will also cause interference Users are advised to make proper channel separation among roaming APs to reduce interference Chz4 c Q D o Q gt Q 3 Q o m I m ITI m Qo N Lower the lime consumption of dedicate AP searching amd make roaming efficent WWW moxa com info moxa com Understanding Industrial WLAN IEEE 802 11 o 2 6 Advanced WLAN Technologies 1 Dual RF Redundancy According a recent VDC report more than 4096 of wireless users are concerned about interference In industrial and critical applications this issue is even more important Normally interference occurs in a dedicated frequency So if we can use 2 or more different frequencies to communicate at the same time then data transmission will not be stopped even if there is interference in one of the frequencies The picture below depicts the standard architecture for wireless infrastructure As you can see access points AP can connect many Clients to an Ethernet network Figure Traditional Wireless Architecture crie ciiam For network redundancy simply use APs and Clients with dual RF and keep the existing architecture usually these 2 RFs are set to 2 4 GHz and 5 GHz to make sure prevent interference To ensure that data can be delivered between the AP and Client even when there is interference in one of the frequencies Moxa devices are equipped w
54. f not an individual AP or another other level like a VPN This is more secure as unauthorized traffic can be denied right at the AP WEP Wired Equivalent Privacy WEP provides a basic level of security to prevent unauthorized access to the network and protect wireless data Static shared keys fixed length alphanumeric hexadecimal strings are used to encrypt data and are manually distributed to all wireless stations that want to use the wireless network WEP has been found to have serious flaws and is not recommended for networks that require a high level of security For more robust wireless security most access points support Wi Fi Protected Access WPA or WPA2 for improved data encryption and user authentication 19 WWW moxa com info moxa com 2009 Industrial Wireless Guidebook 1 Using a Firewall as an Additional Safeguard One of the most basic aspects of maintaining the security of your network involves using a firewall to filter out unwanted traffic To protect a private LAN from unwanted traffic originating outside the LAN firewall software often runs on a gateway that connects the LAN to the Internet The firewall is configured to filter out traffic based on various characteristics of the incoming packets such as IP address MAC address type of protocol etc Even if your private LAN does not connect to a public network once you allow access to the LAN through a wireless AP you open the network to possible ex
55. guration software Alarm messages such as e mail and SNMP trap or user definable TCP UDP raw packets can all be actively pushed to e mail servers SNMP trap servers or TCP UDP servers SMS can be pushed from the Active GPRS I O to an engineer s cellular phone Active OPC server is an exceptionally powerful gateway for Active GPRS I O and plays the role of managing IP addresses GPRS I O device names data acquisition gateways and configuration gateways This is truly the easiest solution for the GPRS industry to eliminate IP address and communication problems 67 WWW moxa com info moxa com 2009 Industrial Wireless Guidebook Benefits of Using Active GPRS 1 0 Moxa s W5340 Active GPRS I O devices come eguipped with 4 analog inputs 8 software configurable DI Os and 2 relay outputs In addition the built in GPRS communication front end intelligence and data logging function give users the advantage of a highly integrated solution The W5340 also features a 3 in 1 serial port RS 232 422 485 for connecting field serial devices such as instruments or meters The benefits of using Active GPRS I O include m A cost effective solution for GPRS telemetry applications m The best choice for solving the dynamic IP issue whether the IP is public or private dynamic or static Easy installation with Active OPC s support the W5340 can push IP addresses and I O status to Active OPC server Flexible Event Handling thanks to th
56. h network This test was done with 32 pcs ol ioLogik E2210 with bandwidth occupation all because of the traditional 640 DUO points AS shown in the figure the Active pull architecture Active tags created by Active Ethernet W O can save 80 of bandwidth consumption OPC Server Lite and ioLogik series products report than passive Ethernet VO the I O status only when it changes This type of save B0 Bandwidth event driven tag status update results in an I O Active Ethernet UO EE response time that is 7 times faster than other OPC l P Passive Ethene LO ii i i ie Server packages using a testing environment with OT A g 2 560 I O channels In a different test of network bandwidth usage Active OPC Server Lite and Test 2 Response Time for UO Status the ioLogik caused an apparent 8096 reduction in This test was conducted with 128 pcs of lologik E2210 network traffic The end result is that I O access is With 2 560 UU points As shown in the figure the active more precise and the cost of communicating with EN T UN Ds ani 9 l architecture in reponse time whan the VO status is remote I O devices is substantially lower especially changed Save B Bandwidih when the remote site has limited bandwidth e g satellite microwave and cellular communication Acbvo Ethornet l O i i PRR At the same time the CPU usage of the SCADA Passive Ethemet lO EBENEN NL HMI system is also reduced by 3596 with this 012 34 5 67
57. he OnCell G3100 device s SMS Tunnel Mode The OnCell G3100 s SMS Tunnel Mode uses a serial port to serial port communication tunnel to send SMS messages There are 3 key inputs involved in transmitting SMS serial data 1 Target phone number of the mobile device that will receive transmitted data 2 Pre approved recipient phone numbers unapproved numbers will be filtered out 3 Data format i e ASCII binary UCS2 SYIOMJAN JeJNIj2D E Unlike GPRS and CSD SMS employs a store and forward mechanism so messages are not transmitted in real time IP Gateways and CSD Some cellular providers offer Circuit Switch Data CSD service which transmits data over voice channels that are always connected such as fax and modem service However CSD calls always occupy the phone which means you will still be charged for service even when you are not sending data In additional data throughput is limited and takes up too many resources As a result cellular providers usually do not offer CSD and the service is no longer offered in some countries At the same time 2G service is also being phased out in favor of 3G technologies Check with your cellular provider to see if they offer these services The OnCell G3100 IP gateway can send IP stacks using PPP Point to Point Protocol capability over CSD service There are 2 mechanisms for setting up your PPP connection 1 The originating OnCell device PPP dials the terminating OnCell device PPPD
58. high attenuation the overall throughput dips bellow the optimum value Throughput can be measured with various throughput measuring tools One of the free throughput measuring tools available is Jperf downloadable here http sourceforge net projects iperf WWW moxa com info moxa com 2009 Industrial Wireless Guidebook 2 2 Wireless Security If you re new to wireless the first thing you should realize is that the signals you send and receive from a nearby access point are easily intercepted by anyone in the vicinity who has a wireless card and a computer The purpose of WLAN security technigues is to render the connection unusable and the data unreadable by anyone but you and the person or machine you re communicating with Although most people do not need in depth knowledge of WLAN security understanding the basics can make it easier for you to find the right product for your application For example one of the most basic guestions you can ask is whether or not a product supports WPA and or WPA2 But why should you care Most wireless products available on the market today support WEP Even though WEP may protect your data from the casual passerby it still leaves you vulnerable to attack from someone with some basic network knowledge and some time on their hands as we point out in the next section i A Peek at the Technology There are two basic aspects to wireless security authentication and encryption Simply put a system us
59. i High M Security High ig edium standard 54Mbps 802 11a g 115200 bps to Th hput k to 100 M 115200 b bus ua uu EM 600 Mbps 802 11n PERSA 1 Mbps E 9 a WWW moxa com info moxa com 2009 Industrial Wireless Guidebook Chapter 2 Understanding Industrial WLAN IEEE 802 11 2 1 IEEE 802 11 Basics Wireless Communication In a wireless environment the communication medium is air Radio waves carrying data propagate from point to point through free space Due to the characteristics of this unguided medium wireless communication calls for a very different set of Knowledge and skills than traditional wired communication systems Getting the most out of your wireless environment requires a basic understanding of the following scientific principles that govern wireless communications i Electromagnetic Waves To understand how energy is transferred through the air we need to review basic electromagnetic theories Electromagnetic EM waves are formed by alternating current rapidly changing direction on a conductive material The rapid oscillation of electric and magnetic fields around the conductor projects electromagnetic waves into the air see the figure below In order for current to be radiated into the air in the form of electromagnetic waves a few factors are critical namely the length of the conductor and freguency of the AC current Higher freguency reduces the reguirement for conductor length LL Z08 3331 NV1M Ieuis
60. ial Wireless Guidebook Despite WiMax s current lead in commercializing its technologies there are signs indicating that LTE is catching up In the past major players like Nokia Siemens Motorola Alcatel Lucent and Nortel showed their support for WiMax But starting from 2008 these players were also showing signs of interests in LTE Nortel had announced not to take part in Mobile WiMax Alcatel Lucent and Motorola also started to discuss LTE announcing they will take part in both WiMax and LTE development This has been interpreted as an indication that WiMax development has fallen short of their expectations The turning point came with the abandonment of Ultra Mobile Broadband UMB When the leading mobile chip provider Qualcomm announced that it will not to invest in UMB but in LTE instead the CDMA camp also decided to adopt LTE as its standard for next generation technologies The unification of both CDMA and GSM in LTE gives LTE a great advantage over WiMax However LTE is not expected to dominate the market any time soon This is because current 3G technologies have raised HSPA downlink speed to 42 Mbps With 100 Mbps possible in the near future with HSPA LTE will need to offer even more incentives to operators in order for it to become the industry standard 4G Status With respect to integration 4G technologies involve more participants technologies industries and applications than just telecommunications It can ther
61. ication At the lowest level they can get raw data from the physical devices in a SCADA HMI system or from the SCADA HMI system in the application The architecture and design makes it possible to construct an OPC Server that allows a client application to access data from many OPC Servers provided by many different OPC vendors running on different nodes via a single object OPCUF Physical LiF ENS or gt ia OPC Application isis Server Physical yr 63 A WWW moxa com info moxa com 2009 Industrial Wireless Guidebook General OPC Architecture and Components The architecture of OPC leverages the advantages of the COM interface which provides a convenient mechanism to extend the functionality of OPC OPC specifications always contain two sets of interfaces Custom Interfaces and Automation interfaces VB OPC Automation OPC Automation Aelicatica Wrapper Local Remote Interface OPC Server m i Shared by many cient Application OPC Custom Interface Server Data Cache Physical Device Data The OPC Specification specifies the COM interfaces but not the implementation It specifies the behavior that the interfaces are expected to provide to the client applications that use them Like all COM implementations the architecture of OPC is a client server model where the OPC Server component provides an interface to the OPC objects and manages them There are several unique considerations in imple
62. ication whether you re using socket mode or operation mode Modem Extension Mode Virtual Modem Modem Extension Mode is a solution for e Extending the distance from the control center to a pure AT modem and e Sending pure AT commands to control your OnCell G3100 device via Ethernet longer distance If you need to control your modem from a longer distance consider using an Ethernet link This solution allows you to keep the serial control interface at the control center and send AT commands from the control center to your OnCell G3100 device by Ethernet You will first need to install OnCell Driver Manager on the controller side to create a virtual COM port which will allow you to control the serial port as if it were a traditional modem and send AT commands to set up CSD calls send SMS messages or link to GPRS You also can install the OnCell modem driver so you can set up dial up networking for your laptop 55 WWW moxa com info moxa com 2009 Industrial Wireless Guidebook 3 5 How to Gonnect Ethernet Devices to Gellular Networks Traditionally Ethernet based devices can only establish TCP IP connections through wired LAN lines At best you may be able to deploy a WLAN environment to communicate with Ethernet devices in the field A WLAN system can eliminate wires and cabling problems when installing and operating the devices It also provides greater mobility especially when the Ethernet devices are moving When it comes to
63. ings they reflect and change their direction and phase If the reflected surface is smooth the reflected signal will likely represent the initial signal and not be scattered All of the above phenomena results in multipath propagation so not all signals arrive at the receiver antenna at the same time due to obstacles that change the signal paths Whether you are setting up an outdoor or indoor application multipath can severely affect received signal quality because the delayed signals are destructive to the main signal The multipath issue can usually be compensated by antenna diversity at the RF level and or by OFDM at the baseband level 1 Modulation and Spread Spectrum The following chart categorizes different digital modulation techniques Digital modulation linear Constant envelope nonlinear Combined hybrid Spread spectrum BPSK BFSK MPSK PN DPSK MSK MearyQAM DSSS QPSK GMSK i MFSK FHSS 1 4 QPSK ODFM 1 E i As you can see there are many RF modulation techniques However our discussion is limited only to the techniques that pertain to the 802 11 standard namely FHSS DSSS and OFDM FHSS Frequency Hopping Spread Spectrum This modulation technique is one of the techniques used in spread spectrum signal transmission It is also Frequency known as Frequency Hopping Code Division Multiple Slot Access FH CDMA Spread spectrum enables a signal to be transmitted across a frequency band th
64. ith a special protocol with almost 0 switching time for seamless redundancy For reliability beyond wireless redundancy Ethernet redundancy is also required Fast ring redundancy like RSTP or Turbo Ring is important on the Ethernet side Figure Redundant Wireless Ethernet Typology 37 a WWW moxa com infogmoxa com 2009 Industrial Wireless Guidebook Introduction to Moxa s Dual RF Redundancy Moxa s advanced AP Client AWK 5000 6000 series product line provides this kind of redundancy The configuration is very easy All you need to do is select redundant AP on the AP side and redundant Client on the client side Then set a different SSID for each RF As shown in the following figure depicting the Web console Ul for Moxa s AWK 5222 set SSID1 for WLAN1 and SSID2 for WLAN2 Figure Dual RF Wireless Redundancy Mode m m A m m y WLAN 1 T WLAH 2 ll red Operation Mode ia van mm Gam E Operation Mode 55ID1 X SSIDZ Chen alie muria mm madame i EE E 1 E h i Wahane Chee wLAHMl 9 933023 si WLAH 2 AWALANS with seme color must have identical AF type SSI and security settings If both the existing Clients and dual RF clients support redundancy in the same network Moxa s AWK 5000 6000 Access Point can connect both types of clients to an Ethernet network As shown in the figure below enter SSID Moxa 1 1 in the 2nd column for the AP to connect the traditional wireless clients with
65. ket share followed by CDMA Code Division Multiple Access K DATA Rate The biggest issues regarding data exchange over a WWAN are the associated costs bandwidth and IP management However as technologies improve and costs drop WWAN is predicted to replace traditional microwave HF radio frequency and satellite communication due to its lower infrastructure costs NOTE The term cellular is also used to refer WWAN technology in general WWAN technologies are discussed in detail Chapter 3 WLAN Wireless Local Area Network As suggested by its name WLAN transmits data over a shorter distance normally 100 meters or so In terms of transmission technology WLAN uses spread spectrum or OFDM Orthogonal frequency division multiplexing modulation technology to provide the convenience of exchanging data without the limitation of cables Today s WLANs are based on IEEE 802 11 standards and are referred to as Wi Fi networks The 802 11b standard which operates around the 2 4 GHz frequency band at 11 Mbps was the first commercialized wireless technology Advances in wireless technology have made a higher transmission rate of 54 Mbps possible with 802 119 which also operates around 2 4 GHz and 802 11a which operates around the 5 GHz frequency band It is now very common to see dual band Wi Fi access points and client network adaptors that support a mixture of 802 11a b and g standards More bandwidth means that it is possible to us
66. lator Moca You can use the Moxa Antenna Calculator to calculate the E output power of the access points as well as the achievable ee distances and data rates The program can be used from our NT website at www moxa com Event IW 2009 Industrial_Wireless_ A G M Typology index htm T H Tis After selecting your components access points antennas cable etc the calculator works out the data rates ranges and the antenna gain settings that have to be entered into the access point Positioning the Antennas Antennas do not broadcast their signals linearly but within an angle that depends on the model in question The spherical expansion of the signal waves results in amplification of or interference to the effective power output at certain intervals of the connection between the transmitter and receiver The Fresnel Zone must remain free from obstruction in order to ensure that the maximum level of output from the transmitting antenna reaches the receiving antenna Any obstructing element protruding into this zone will significantly impair the effective signal power The object not only screens off a portion of the Fresnel Zone but the resulting reflections also lead to a significant reduction in signal reception The concept of RF LOS is based on a parabolic free space zone called the Fresnel Zone that will ensure a more stable link if at least 6096 of the vertical radius is kept obstacle free The figure below show
67. ll can be both TCP Server and TCP Client 3 6 How to Connect l O Devices to Cellular Networks 59 SCADA Meets Ethernet Communication from I O to SCADA OPC Fundamentals OPC and DCOM 5 Things You Need to Know Enhance OPC Capability for Cellular Communications Conclusion Differentiating Between Wireless Technologies gt Chapter 1 Differentiating Between Wireless Technologies m d kad 7 1 1 WWAN vs WLAN vs WPAN Modem wireless technologies are developed for the growing demand in mobile data exchange Since demands vary depending on the application different technologies are applied to meet specific needs Normally wireless technologies are divided into three categories WWAN WLAN and WPAN Coverage Jaen LIEN W YAN osui Gem eose uep SOFAS enZ 300M 100M WPAN IEEE 802 154 Bluetooth T ZigBee neon uw 1 Mbps 10 Mbps 100 Mbps WWAN Wireless Wide Area Network A WWAN utilizes mobile cellular communication networks such as cellular UMTS GPRS CDMA2000 GSM CDPD Mobitex HSDPA 3G and WiMax All of these networks offer wide service coverage and are normally used for citywide nationwide or even global digital data exchange Cellular networks in particular are operated by carriers such as Cingular Wireless Vodafone and Verizon Wireless In cellular communication GSM Global System for Mobile Communication is the leader with over 8096 mar
68. mains in a Layer 2 network Traditional networks use routers to define broadcast domain but it is now possible to set the broadcast domain boundaries with Layer 2 switches That is to say a VLAN can add two or more hosts that were in different subnets to be grouped into the same LAN segment disregard of their geographical locations VLAN provides the leeway to the network administrators to address network security management and scalability issues vA How to Set Up VLAN with IEEE 802 11 Every time a packet is sent from one switch to another over a VLAN VLAN tagging is required VLAN tagging is the practice of inserting a VLAN ID in the packet header so the packet can be identified and forwarded to the right port or interface The IEEE 802 1q standard is the most commonly seen VLAN tagging protocol created by IEEE group The tagging protocol supports a maximum of 4096 VLANs c Q D o Q gt Q 3 Q o m I m ITI m Qo N By borrowing the same concepts it is now also possible to apply VLAN to an IEEE802 11 wireless network Many wireless access points AP are now equipped with VLAN capability A single AP can now be configured to assign a different service set identifier SSID to different VLANs Also the authentication settings like MAC EAP and VLAN ID are required to configure a wireless VLAN Wireless VLAN Limitations Wireless VLANs bring many benefits to WLAN applications but there
69. menting an OPC Server The main issue is the frequency of data transfer over non sharable communications paths to physical devices or other databases Thus we expect that OPC Servers will either be a local or remote EXE which includes code that is responsible for efficient data collection from a physical device or a database An OPC client application communicates to an OPC server through the specified custom and automation interfaces OPC servers must implement the custom interface and optionally may implement the automation interface In some cases the OPC Foundation provides a standard automation interface wrapper This wrapperDLL can be used for any vendor specific custom server SXJOM 9N JeJNIj2D E OPC Servers now register with the system via Component Categories This allows the Microsoft ICatlnformation IID ICatlnformation Interface on the StdComponentCatagoriesMgr CLSID_ StdComponentCategoriesMgr to be used to determine which OPC servers are installed on the local machine The problem is that this does not work for remote machines because the Component Categories Manager is a DLL and the ICatlnformation interface only works in process As a result there is no easy way for a Client including the Foundation supplied Automation Wrappers to obtain a list of OPC Servers installed on a remote machine The OPC Foundation supplied Server Browser OPCENUM EXE can reside on any machine will access the local Component Categories Manager and pro
70. n below so it can be used in environments where APs cannot be wired LAM 1 Denis Bathing Balertian Figure Bridge Mode for Extra APs SSI pera Wide Action Hui kinkiEg dp v aj Em WAN ras WA 77 An uh A Ar Master va SSIDL2 Slave RAN L WLAN e 498 e b s Master Clave WILA Ns with seme color must have identical AF type 5506 and security settings t Mesh Technologies Mesh technologies are generally considered to be wireless communication systems that are interconnected to each other However there are two distinctive ways to build up a so called mesh network wireless distribution systems WDS and mesh routing Both of these methods create Layer 2 connections to one or more bridges mesh routers to allow data to be passed between them WDS differs from mesh routing in many ways Generally WDS has the nature of a more static network configuration without significant demand for redundancy That is a wireless bridge is configured to point to the adjacent bridge with a predefined MAC address So when a bridge fails and while there is no adjacent bridge is configure to serve as a backup path the link will be lost A wireless mesh routing link on the other hand can provide greater redundancy because it can create a redundant path in the event of node failure In other words the mesh router automatically detects a new node when the original node fails and dynamically determines the best path While a WDS is more
71. n is relative to an isotropic radiator i e a radiating sphere in space This ideal radiation is impossible to realize but its pattern is the reference for all realizable antennas The gain of a passive antenna is measured by how effectively the antennas can focus the energy how narrow is the antenna angle rather than the actual boost in transition power Therefore the narrower the antenna angle the higher the antenna gain The diagram below shows the antenna angles of a high and low gain antenna B Low Gain Antenna High Gain Antenna Transmit Power and Received Sensitivity When a radio signal is being transmitted through the air it will experience a great loss in signal strength caused by attenuation introduced by free space Therefore when evaluating a wireless system one needs to be aware of the signal power level at the transmitter end and at the receiver end The signal power received cannot be so weak as to break the communication link or too strong as to saturate the receiver s amplifiers These concerns call for estimating the power budget of a wireless system By making a power budget estimation you will have an idea of how far you can extend your wireless link without losing communication Please note that the following calculations are pure theoretical estimations that are not meant to guarantee communication distance There are many other factors involved that will affect transmission distance Pt
72. nd decryption of data To save valuable cellular network resources some M2M solution providers offer a software solution to help customers cope with the private IP problem That is manufacturers provide middleware that works as a communication gateway 7 Moxa OnGell Gentral Manager The OnCell G3100 series is Moxa s cellular IP gateway that connects serial or Ethernet devices to cellular networks As a leading industrial networking solution provider Moxa is aware of the private IP issue troubling many of our M2M customers To solve this problem Moxa has introduced OnCell Central Manager Simply install OnCell Central Manager onto a Server PC with a public IP address and register the IP addresses of OnCell devices in your private network on the Client OnCell IP gateway As soon as the OnCell IP gateway is powered on it will initiate the connection to OnCell Central Manager Thanks to OnCell Central Manager your access points can now communicate with field devices via cellular networks so you don t need to worry about paying extra VPN service fees or wasting valuable cellular network resources OnCell Central Manager with public IP address Moxa OnCell G3110 3150 TCP Server Service forwarding port ssss IP gateway Telnet portzxxx V y A e datalcmd yyyy zzzz i ON Ethernet Serial 7 TCP Client Ethernet Device Serial Device TCP Server TCP Server 49 WWW moxa com info moxa com 2009 Industrial Wir
73. ng On WLAN devices the most commonly used antenna connector is PRSMA and N type for IEEE 802 11 wireless applications N type male N type female RP SMA female RP SMA male SMA female SMA male Half Power Beam Width HPBW This parameter is measured from the antenna s radiation pattern and refers to the beam width at which the antenna s radiation drops to half of its peak value It also refers to the antenna s effective coverage area Once you get outside the half power beam width the signal typically drops off very quickly A very high gain antenna has a very narrow angled half power beam width which makes the directionality high as well Antenna Polarity Polarization refers to the direction in which the electromagnetic field lines point as energy radiates away from the antenna The simplest and most common type is linear polarization When power is sent from transmitter to receiver only that portion of the beam with the same polarization can be received An improper antenna installation may decrease performance 21 WWW moxa com info moxa com 2009 Industrial Wireless Guidebook Frequency Different wireless applications use different freguencies to achieve their purposes To make sure wireless devices work as expected users need to choose the right antenna with the right freguency For example using a 5GHz IEEE 802 11a application with a 2 4GHz antenna can weaken or even completely wipe out the signal 1 Choosi
74. ng the Right Antenna for Your Project In addition to the key antenna specifications outlined above there are some very simple tips you can use to choose the right antenna for your wireless project For a fixed point to point connection we recommend choosing a directional antenna Rather than broadcasting their signals linearly directional antennas form a Fresnel Zone a spherical expansion of the signal waves and increase signal strength The increased signal strength ensures smoother data transmission and connection NI When facing an application that requires constant changing of locations omni directional antennas make a better choice An omni directional antenna emits waves equally in all directions so it is easier for moving objects with constantly changing angles and positions to receive signals A few applications require special types of antennas such as a leakage antenna for collecting data along rail tracks These are very special cases and the deployment and infrastructure costs can be very high c O D P o e Q Q O c o e EX m c m ITI m Qo e NO en mah WWW moxa com info moxa com 22 Understanding Industrial WLAN IEEE 802 11 9 2 4 Long Distance Wireless Wireless transmissions today are based upon the IEEE 802 11 protocol stacks By modifying these stacks wireless solution providers can optimize them for long range point to point applications It has also been used in
75. nna KETAS SK o 2 4G AP gt Station Mbps 15 686 11892 11 066 0 306 2 4G Station AP Mbps 14703 13 176 11 691 0204 SG AP Station Mbps 12889 0 6 934 N A LL 208 333l NV 1M Ieuisnpuj Guipuejsaepur 5G Station gt AP Mbps 25 15085 7553 NA N A Not Available ANT WSB5 PNF 18 Uni directional 5G 18dBi antenna Distance Km 5G AP gt Station Mbps 25 022 5G Station AP Mbps 26 456 N A Not Available ANT WSB PNF 18 Uni directional 2 4G 18dBi antenna Distance Km 2 4G AP gt Station Mbps 2 4G Station AP Mbps N A Not Available WWW moxa com info moxa com 35 Understanding Industrial WLAN IEEE 802 11 9 2 5 Mobile Optimization In mobile applications that involve multiple access points APs the speed and roaming handover mechanism can be crucial to a project s success In the world of wireless roaming refers to when a client moves between two or more access points As a result seamless connection is reguired for the client to roam from one AP to another Simply put as the client physically moves from one AP to another the signal from the first AP will drop while the signal strength from the other AP will increase By the time the signals from the first AP drop below the signals from the second AP the client will have roamed to the second AP There are a number of factors that will affect the smoothness of roaming These include the topology
76. npuj Buipuejsaepu E E Plane The conductors are called antennas Antennas transform electric energy into EM waves during transmission and turns EM waves into electric energy during reception The size and length of the antenna Jii m is directly proportional to its desired transmission reception freguency As shown in the figure to the right electromagnetic waves are radiated from a directional antenna in a parabolic shape As EM waves propagate through the air they will experience different types of alterations as they are intercepted by different obstacles Obstacles in the signal path introduce the following alteration to the signals WWW moxa com info moxa com 10 Understanding Industrial WLAN IEEE 802 11 oo Diffraction Shadow Fading Signal strength is reduced after experiencing diffraction Obstacles causing diffraction usually possess sharp edges such as the edges of buildings When EM waves encounter an obstacle with sharp edges that cannot be penetrated the EM waves wrap around the obstacle to reach the receiver Scattering When EM waves encounter many small obstacles smaller than wave length the EM waves scatter into many small reflective waves and damage the main signal causing low quality or even broken links Such obstacles include rough surfaces rocks sand dust tree leaves street lights etc Reflection When EM waves run into large obstacles such as the ground walls or build
77. of a standard and a mesh routing link is more of a proprietary standard they are being adopted in accordance with users needs A WDS is often employed in a hierarchical network topology for bridges that can not prevent broadcast storms As a result a WDS is often configured in spanning tree topologies A bridge loop is often avoided to prevent a broadcast storm However there are software solutions which utilize Spanning Tree Algorithms STA to compute the best path between two nodes while putting all other paths in blocking mode This realizes communication redundancy in a WDS but it can be time consuming to create a workable bridge loop So a WDS is often adopted in a small network that requires manual configuration for each node Once the connection is established it is not easily interrupted Mesh routing on the other hand is often adopted in systems that require higher redundancy It often needs few manual configurations for each node and provides greater expandability when more nodes are to be added in the future In summary redundancy is the primary concern when choosing mesh routing links It is also more of a suitable choice when the connections are subjected to constant disruptions for example by passing by buses 39 WWW moxa com infogmoxa com 2009 Industrial Wireless Guidebook T Wireless VLAN A Virtual LAN VLAN as defined in IEEE is a group of hosts grouped together as if they were attached to the Broadcast do
78. of other sources of interference that aggregate into a formidable obstacle to enabling long range use in occupied areas microwave ovens baby monitors wireless cameras remote car starters wireless phones and Bluetooth products e Landscape interface Obstacles are among the biggest problems when setting up a long range wireless application Trees and forests degrade the microwave signal and rolling hills make it difficult to establish line of sight propagation In a city buildings will impact integrity soeed and connectivity Steel frames partly reflect radio signals and concrete or plaster walls absorb microwave signals significantly but sheet metal in walls or roofs may efficiently reflect wireless signals causing an almost total loss of signal Power Amplifier Moxa supplies RF devices with 63 200 800 mW and boosters to extend your wireless range For example if you have a 18 dBm 63 mW device and replace Moxa s 200 mW RF device you can increase 18 dBm 63 mW to 23 dBm 200 mW if you replace Moxa s 800 mW RF device you can increase 18 dBm 63 mW to 29 dBm 800 mW Based on our experience you can increase the range by using Moxa s HF devices or boosters 25 WWW moxa com info moxa com 2009 Industrial Wireless Guidebook External Antennas Moxa s 802 11a b g n wireless AP bridge client devices are supplied with a low gain antenna However for many of the long range applications additional external antennas
79. of the access points gain and coverage of the antennas and the roaming threshold settings on the client To ensure smooth roaming we first have to take into consideration the routes of the moving object and carefully plan the wireless AP deployment configuration Different applications encounter different roaming conditions but we will use linear roaming as an example to illustrate how roaming is conducted and what factors we need to pay special attention to t Roaming Under Linear Movement A client is moving from left to right across three different APs As the client moves the signal from the first AP drops and the signal strength from the second AP increases Most of the commercial wireless clients only monitor the communication quality as the basis for roaming decisions That is to say when the signal from first AP drops and frames can not be transmitted the client in an IEEE 802 11b application will first drop the communication speed from 11 Mbps to 5 5 Mbps and then to 2 Mbps and 1 Mbps If the communication quality is still poor and frame transmission continues to fail the client will decide to roam from the first AP to the second AP Channel 1 Channel 6 Channel 1 Movement of client A roaming mechanism of this sort might be able to satisfy many non critical applications However this type of mechanism severely impairs the smoothness of data transmission for video or audio applications which require higher quality data tr
80. ontext request 4 Activate POP context accapt IP address galiated Quas Data Transmission Receive PDP context activation procedures are as follows a A 0 N Mobile phone sends out PDP context activation request and other relative parameters e g APN QoS SGSN begins verification based on previously stored GPRS Attach information DNS mechanism in SGSN analyzes the APN and returns a GGSN address SGSN and GGSN build logic links GGSN will instruct an IP address for the mobile phone and send it to the MS via SGSN The external network can then start a session with the MS APN Access Point Name Access Point Name is a label according to DNS naming conventions describing the access point to the external packet data network PDN An APN is a logical way to name a GPRS service The Domain Name Service DNS server translates the APN into the GGSN IP address APN string naming comes from the mobile operator There is no common rule so customers need to request 1 GPRS service and 2 the APN string from their operator Some operators offer different APNs according to the GPRS service level such as public fixed IP addresses non port blocking or VPN IP Address Allocation in GPRS Fixed addressing IP address is stored in HLR HLR sends IP address to SGSN then SGSN sends IP address to the MS IP address is sent to the MS when the MS wants to send data Dynamic addressing GGSN receives the I
81. or some industrial applications where the control elements are often involved It is a basic control requirement that communication must not be interrupted To meet this requirement there are some proprietary 2 4GHz band wireless devices that use FHSS spread spectrum technologies to meet the needs for higher noise resistance In summary FHSS sacrifices throughputs and communication ranges for more stability Table WLAN vs Proprietary Wireless Frequency 2 4 GHz ISM 900 MHz license needed 2 4 GHz ISM Standard IEEE 802 11 Proprietary Proprietary Spread Spectrum DSSS OFDM a FHSS FHSS Throughput 22 Mbps 115200 bps 115200 bps Distance 10 km 10 km 3 2 km Communication method Point to multiple points Point to point Point to point a FHSS utilizes frequency hopping to avoid signal interference Bluetooth is one example that uses this technology In the early days IEEE 802 11 also used FHSS but has since adopted DSSS Direct Sequence Spread Spectrum out of security concerns 802 11a 801 11g and 802 11n adopt OFDM to increase their resistance to external interferences About modulation and spread spectrum please refer to Chapter 2 1 i WWAN vs WLAN vs WPAN vs Proprietary RF GSM GPRS CDMA Bluetooth Standard WCDMA WiMax IEEE802 11 eee No Standard i Point to point GSM eae ON pan LAN TCP IP Point to point Point to Point Mode WAN GPRS 3G icati 1 to 1 a ICA 5 km to 30 km 100 mto 300 m Approx 10m SUDO coverage km Low not
82. perature range of 25 to 40 C or 40 to 85 C for electronic devices When the trains enter and leave a tunnel the temperature change can be very drastic As a result electronic devices must also be able to withstand a 3 C sec temperature change and thermal shock that leads to condensation on the PCB Shock and Vibration EN50255 follows the test standards of EN67373 Electronic devices must withstand at least 1 G vibration when mounted on a DIN Rail Chassis mounted devices are required to withstand a shock rating as high as 50 G Atmospheric Pollutants Combustible dust accompanied by oil sulphur dioxide and salt spray in the air create a hazardous environment for rolling stock applications As a result an EN50155 compliant device must have a high IP rating Air Cooling Force air cooling systems are not allowed EN50155 electronic devices must have conductive only mechanism designs to eliminate potential maintenance problems that arise from fan cooling systems Moxa AWK Series Meet EN50155 and EN50121 3 2 50121 4 Standards for Rail Traffic Certified to Meet Industry Standards Rail vehicles require the highest standards of stability due to random vibrations that occur during normal operation The EN 50155 standard covers electronic equipment used on rolling stock and EN 50121 4 defines the emission and immunity of signaling and telecommunication apparatus They outline the issues that need to be addressed to ensure that railway elec
83. platforms provide a service called ping that can be used to measure round trip latency Ping performs no packet processing it merely sends a response back when it receives a packet i e performs a no op so it is a relatively accurate way of measuring latency Where precision is important one way latency for a link can be more strictly defined as the time from the start of packet transmission to the start of packet reception The time from the start of packet reception to the end of packet reception is measured separately and called Serialization Delay This definition of latency is independent of the link s throughput and the size of the packet and is the absolute minimum delay possible with the link latency of the LAN you can measure by specified device with input to output delay time in serialization WWW moxa com info moxa com 48 Cellular Networks o As a result of WAN latency from cellular networks you cannot count the number of nodes in your link as the timing is different for each link Therefore delay time in cellular networking is immeasurable and not suitable for real time systems i Solution for Private IP A common problem in M2M network planning is that cellular operators and service providers usually only provide private and dynamic IP addresses The reasons for doing so are threefold 1 In the world of Internet communication one of the biggest problems is that the number of public IP addresses is running out quickl
84. pplications Earth Bulge may need to be taken into consideration as an obstacle c O D o RV Q 3 Q o I m ITI m Qo N WWW moxa com info moxa com 28 Understanding Industrial WLAN IEEE 802 11 9 The precise alignment of the antennas is of considerable importance in establishing long range wireless connections The more central the receiving antenna is located in the ideal line of the transmitting antenna the better the actual performance and the effective bandwidth are If the receiving antenna is outside of this ideal area however significant losses in performance will result The current signal quality over a long range wireless connection can be displayed on the device s LEDs or in the Moxa monitor in order to help find the best possible alignment for the antennas The more LED indicators means the stronger the connection In the Moxa monitor the connection quality display is opened with the context menu once signal monitoring has commenced The P2P dialog displays the absolute values for the current signal strength and the maximum value upon starting the measurement The development of the signal strength over time and the maximum value are displayed Initially only one of the two antennas should be adjusted until a maximum value is achieved This first antenna is then fixed and the second antenna is then adjusted to attain the best signal quality
85. private IP addresses and assigns one to the GPRS subscriber Floating private IP address Always Client role to access server Class A 10 XX XX XX Can be Client or Server role IP address is always changeable needs a SX4JOMJ 9N JeJNI 2D E Mobile operator keeps a pool of public Floati lic IP UC IP addresses and assigns one to the address CO a a notification mechanism to update public IP address Mobile operator keeps a dedicated IP Ear DZ e Bapa r l Fixed public IP address for each SIM card based on P address is fed needsa special bii address the SIM card s IMSI ID code and user E rate from operator service level As you can see from the table above the kind of WAN IP address obtained from your cellular operator will affect network planning and determine the role of the devices configured with the IP address Private IP addresses are suitable for Client role Public IP addresses are suitable for Client role and Server role i Delay Time Latency in a packet switched network is measured either one way the time from the source sending a packet to the destination receiving it or round trip the one way latency from source to destination plus the one way latency from the destination back to the source Round trip latency is more often quoted because it can be measured from a single point Note that round trip latency excludes the amount of time that a destination system spends processing the packet Many software
86. ransmission However it becomes more of an issue when it comes to audio and especially video Video requires high quality of flow and throughput control and lower error rates All these are In multimedia data transmission it is important for delays arising from network latencies to be undetectable to users IEEE 802 11e was set up to answer this call for QoS in WLAN IEEE 802 11e is the amendment that defines wireless LAN QoS enhancement in IEEE 802 11 WLAN QoS is achieved through modifications to the Media Access Control MAC layer solving the latency delay problem that is sensitive to multimedia and voice data transmission od t Wireless Management QoS is essential for wireless communication It is an important element for wireless applications when it comes to management There are three layers of management namely device management network management and centralized management ur lt N TO LO Pri awi 5222 Device Management When it comes to network management device management is always the most basic task for all network administrators Often wireless APs Clients come with a management utility or web console that allows network managers to locate and remotely configure the wireless APs Clients Network Management Above device management is the network management layer This layer requires a higher level of software utilities to manage all wireless nodes The network management utility should be
87. rated in the schematic below wireless encryption has evolved from WEP which was released in 1999 to the 802 11i standard more commonly referred to as WPA2 t The Evolution of Wireless Encryption WPA2 WPA2 is the second generation of WPA The primary difference between WPA and WPA2 is the technology used for data encryption WPA uses Temporal Key Integrity Protocol TKIP for data encryption whereas WPA2 uses Advanced Encryption Standard AES a stronger encryption technology suitable for industries that require highly secure networks WPA Wi Fi Protected Access WPA is a stronger security method that was created in response to the flaws discovered in WEP It was intended as an intermediate measure until further 802 11i security measures were developed When implemented with authentication methods such as RADIUS WPA is considered secure enough for all but the most sensitive enterprise applications For most home and small business use an effective level of security can be obtained by using WPA with a pre shared key PSK that is shared by all users 802 1X 802 1X is an authentication method that prevents unauthorized users from entering the network It is used with WPA to form a complete WLAN security system On many wireless systems users either log into individual access points or can freely enter the wireless network but cannot get further without additional authentication 802 1X makes users authenticate to the wireless network itsel
88. rds WiMAX Worldwide Interoperability for Microwave Access Led by Intel Corporation this is the 4G technology with the farthest transmission range Its highest downlink and uplink speed under mobile communication environments can reach 75 Mbps and 50 Mbps respectively On November 12 2008 HTC and Russian carrier Scartel branded Yota jointly launched the world s first GSM WiMAX integrated dual module mobile phone HTC Max 4G UMB Ultra Mobile Broadband Led by Qualcomm Inc this is the evolution standard of CDMA technology It has the highest transmission speed among 4G technologies currently The highest downlink and uplink speed under mobile communication environments can reach 288 Mbps and 75 Mbps respectively LTE Long Term Evolution LTE is led by ETSI Its highest downlink and uplink speed under mobile communication environments can reach 100 Mbps and 50 Mbps respectively In December 2008 the Third Generation Partnership Project also known as 3GPP announced 3GPP Release 8 to enhance data transmission speed in mobile networks Release 8 standardizes the LTE and makes it a more viable candidate for the nascent 4G standard LTE uses both Frequency Division Depex FDD and Time Division Duplex TDD and is able to operate on different bands ranging from 700 MHz to 2 6 GHz This also makes it possible to incorporate the now incompatible GSM and WCDMA and also reduces costs E 5 WWW moxa com infogmoxa com 2009 Industr
89. rewall is turned off for a short period of time Check with the Network Administrator to ensure it is safe to turn off the Firewall temporarily Set Up Mutual User Account Recognition To enable both computers to properly recognize User Accounts it is necessary to ensure that User Accounts are recognized on both the OPC Client and Server computers This includes all the User Accounts that will require OPC access If there are no User Accounts or Passwords already on the computers please add them to both computers Configure System wide DCOM Settings OPC specifications depend on Microsoft s DCOM for the data transportation Consequently you must configure DCOM settings properly It is possible to configure the default system wide DCOM settings as well for a specific OPC server The system wide changes affect all Windows applications that use DCOM including OPC application In addition since OPC Client applications do not have their own DCOM settings they are affected by changes to the default DCOM configuration OPC communication only requires Connection Oriented TCP IP so add Anonymous Logon required for OPCEnum and Everyone to the list of Group or user names in each tab Configure Server Specific DCOM Settings Once the system wide DCOM settings are properly configured turn attention to the server specific DCOM settings In the OPC Server specific settings only the Identity tab needs to change from the default
90. rk resource is wasted when a data call is utilized in a GSM network That is because data transmission doesn t necessarily need real time transmission which is primarily required for voice or video communications A few seconds delay won t change the correctness and consequence in data transmission Take email uploads and downloads for example The network resource is occupied only when data is transmitted through the packet switching system As a result other users can freely send their data when the system is inactive Accordingly consumers benefit from the low cost and real time data transmission of GSM networks General packet radio service GPRS is a packet oriented mobile data service available to 2G and 3G GSM users E A GSN GPRS Support Node is a network node that supports the use of GPRS in the GSM core network All GSNs should have a Gn interface and support the GPRS tunneling protocol There are two key variants of the GSN namely Gateway GGSN and Serving GPRS Support Node SGSN e Serving GPRS Support Node SGSN A Serving GPRS Support Node SGSN is responsible for the delivery of data packets from and to the mobile stations within its geographical service area Its tasks include packet routing and transfer mobility management attach detach and location management logical link management and authentication and charging functions The location register of the SGSN stores location information e g current cell current VL
91. rtification for rail traffic applications We hope this guidebook will provide you with a more comprehensive understanding of industrial wireless technologies and serve as your best guide to getting un wired It s time to go wireless Moxa Inc www moxa com gt infotmoxa com Table of Contents Chapter 1 Differentiating Between Wireless Technologies 1 1 WWAN vs WLAN vs WPAN 3 WWAN Wireless Wide Area Network WLAN Wireless Local Area Network WPAN Wireless Personal Area Network 1 2 Evolution of Cellular Networks 4 3G Technologies 4G Technologies 1 3 Evolution of IEEE 802 11 7 EEE 802 11n EEE 802 11s 1 4 WLAN vs Proprietary 2 4 GHz 9 Chapter2 Understanding Industrial WLAN IEEE 802 11 2 1 IEEE 802 11 Basics 10 Electromagnetic Waves Signal Power Bandwidth Data Rate and Throughput 2 2 Wireless Security 18 A Peek at the Technology The Evolution of Wireless Encryption Using a Firewall as an Additional Safeguard 2 3 Antenna Theory and Selection 21 Functions of Antennas Types of Antenna Key Antenna Specifications Choosing the Right Antenna for Your Project 2 4 Long Distance Wireless 23 Application Topology Components of the Expanded 802 11 Wireless System Moxa s Ant
92. s how to estimate the Fresnel Zone of a wireless link where r meter is the vertical radius of the oval d km is the distance between the transceivers and f GHz is the radio frequency r In mis 1 7 32X i d in km 4f im GHz 27 WWW moxa com infogmoxa com 2009 Industrial Wireless Guidebook To ensure that the Fresnel Zone remains unobstructed the height of the antennas must exceed that of the highest obstruction by this radius The figure below shows the full height of the antenna mast H H1 H2 D Distance Between Antennas H1 Added Antennas Height for Fresnel Zone Clearance H2 Added Antennas Height for Earth Bulge Clearance Antenna Gains The gain of each antenna specifies its directionality In general the lower the gain the more evenly distributed in all directions the radiation will be High gain antennas on the other hand emit radiation in a more specific direction The gain defines its power gain or directive gain in terms of the ratio of the intensity or power per unit surface In general when we choose an antenna the longer the transmission distance the higher the antenna gain must be At the same time we must sacrifice omni directional coverage 1 Antenna Alignment for P2P Operations When there is not enough obstacle free Fresnel Zone available you may need to relocate the wireless devices or elevate the antennas to clear more Fresnel Zone space see figure below In long distance a
93. s or customized high power modules to amplify the transmit power However such attempts may cause the system to exceed the radio emission regulations i e FCC regulations of one s country so take caution during high power operation dB dBm dBi Power measured in mW is hard on the math when we are dealing with extremely small power levels at the receiver end Therefore instead of using absolute values milliwatts we often convert them into dBm The unit of dBm is a logarithmic representation of mW The conversions are as follows ilS WWW moxa com info moxa com 2009 Industrial Wireless Guidebook The following table shows some common conversion values between dBm and mW Pj 10 logP dBm Wat dBm Wat 40dBm 10W 12dBm 16mW ER E log DME 30dBm 1W 9dBm 8mW 10 20dBm 100mW 6dBm 4mW 10dBm 10mW 3dBm 2mW OdBm 1mW OdBm 1mW 10dBm 100uW 3dBm 500uW 20dBm 10uW 6dBm 250uW 30dBm 1uW 9dBm 125uW 40dBm 100nW 12dBm 62 5uW The dB is a unit of relative quantity which means it is merely a multiplication factor used to represent the gain or loss of signal power A useful rule of thumb is an addition or subtraction of 3 dB is equivalent to a multiple of 2 or 0 5 An addition or subtraction of 10 dB is equivalent to a multiple of 10 or 0 1 617 In dealing with antenna gain specifications the gain factor is often represented by dBi The i stands for isotropic which means the gai
94. signal across 1 000 or more signal carriers simultaneously The signals are sent at right angles orthogonal to each other so they do not interfere with each other OFDM has the ability to overcome multi path effects by using multiple carriers to transmit the same signal OFDM is commonly used in IEEE 802 11a and 802 11g standards Non near line of sight associations can be achieved using the OFDM technique The following table summarizes the modulation techniques c O D o RV S Q 3 Q o Z I m ITI m Qo N Med Less resistance More resistance Much less 22 MHz wide contiguous 79 MHz wide contiguous multicarrier Interference bands bands modulation Interference Medi High L susceptibility Sem 9 uid Collocation Less More is uia paral sub carriers Compatibility 802 11b WiFi Alliance None 802 11a 802 11g Implementation Cost Comparatively Less Comparatively more High Throughput 5 6 Mbps 2 Mbps for 802 11 25 Mbps WWW moxa com info moxa com 12 Understanding Industrial WLAN IEEE 802 11 9 Lastly let s use the 802 11g standard as an example for how the transmission type and modulation scheme corresponds to each data rate 802 11g Data Rate Transmission Modulation Mbps Type Scheme 54 OFDM 64 QAM 48 OFDM 64 QAM 36 OFDM 16 QAM 24 OFDM 16 QAM 18 OFDM QPSK1 12 OFDM a QPSK 11 DSSS CCK2 a QPSK Quadrature Phase Shift Keying 9 OFDM BPSKS D CCK Complementary Cod
95. ss devices use different antennas to operate in different frequencies and to achieve for example a desired range The most important parameter of an antenna is its working frequency For example a 2 4GHz antenna is too weak to use in IEEE 802 11a communication and the data rate will fall back to a very low level or even drop to ground zero i Types of Antenna There are two basic types of antennas omni directional and directional The two types are categorized by the direction in which they beam radio signals Omni directional antennas are designed to radiate signals equally in all directions Use this type of antenna if you need to transmit from a central node such as an access point to users scattered all around the area Directional antennas provide a more focused signal than omni directional antennas Signals are typically transmitted in an oval shaped pattern with a beam width of only a few degrees With higher gain directional antennas can also be used outdoors to extend point to point links over a longer transmission distance or to form a point to multipoint network t Key Antenna Specifications Connector types Before you purchase an antenna for your wireless device you should check the type of antenna connector that your device uses You will need to buy an antenna with a matching connector There are several types of antenna connectors including MCX TNC N type SMA and RP SMA RP stands for reverse polarity or reverse pi
96. t PLC1 compares the measured flow to the setpoint controls the speed pump as required to match flow to setpoint Mix and Match SCADA SCADA HMI systems evolved in three stages including Monolithic Distributed and Network SCADA systems Monolithic SCADA involves an independent system for single station and uses a vendor s proprietary communication protocols As the number of monitoring sites increased multiple stations were required for monitoring and control in a Distributed SCADA system The introduction of LAN technology in the late 1990s provided SCADA systems with real time monitoring capabilities At the time most communication protocols were proprietary SXJOM 9N JeJNIj2D E SCADA HMI System Evolution i pen system architecture DA pom Open standard and protocols Accessible fram the internet Adopt Information Technology Multiple Stations Connected through LAN shared information in real tine Proprietary communication protocols wv Distributed SCADA system pr Independent system Monolithic SCADA system Single Station c Proprietary communication protocols Mid ol 19905 Late of 19905 2000s Due to a limited choice of equipment when requirements changed open communication protocols became increasingly popular such as Modbus RTU and Modbus ASCII originally both developed by Modicon over RS 485 By 2000 most I O makers offered completely open interfacing such as Modbus TCP over Etherne
97. t and IP Today Network SCADA systems which use open system architecture standards and protocols distribute functionality across a WAN rather than a LAN It is now easier to connect third party peripheral devices because of the adoption of information technology IT field protocols such as Internet Protocol IP are used for communication between the master station and communications equipment Due to the use of standard protocols many Network SCADA systems are accessible from the Internet SCADA systems are coming in line with standard networking technologies Ethernet and TCP IP based protocols are replacing the older proprietary standards A key protocol is OPC Client Server protocol WWW moxa com info moxa com 60 Cellular Networks oo Although it allows different equipment from different vendors to communicate with each other it does not utilize the bi directional and push technology advantages of Ethernet networks For example if an intelligent device wanted to send alarms and execute front end logic it could take advantage of Ethernet network communication technology used in IT The vast majority of markets have accepted Ethernet networks for their HMI SCADA systems What does the future have in store Experts foresee the next generation of SCADA to be a mix and match system that takes advantage of XML web service push and other modern web technologies New Push Technology from Moxa Active OPC Server Active OPC
98. technology that is ubiquitous ambient and everywhere can involve subscribers in the system completely Wi Fi or the system implemented in the future may be applied This concept also includes Smart Radio technology and has higher spectrum use and transmission capability Moreover it can also filter and transmit large volumes of information Table 4G Technology Comparison Standards Setting Organization RTSI QCom Intel Original Tech WCDMA CDMA2000 1xEV DO Maximum Speed 100Mbps 50Mbps 288Mbps 75Mbps 70Mbps 70Mbps Wireless Tech OFDM MIMO SC FDMA MIMO SDMA MIMO SOFDMA Schedule 2008 draft 2009 2008 soiDoJouuoe SSaJAUIM ueeAgeg Hulenuseyjig E WWW moxa com infogmoxa com Differentiating Between Wireless Technologies 5 1 3 Evolution of IEEE 802 11 With the advent and development of local area networks LAN IEEE 802 3 has been widely adopted in many different kinds of communication applications The continued prevalence of wired communication has also contributed to the growing demand for wireless communication In 1997 IEEE released the IEEE 802 11 standards that define the Physical Layer and Data Link Layer of TCP IP allowing communication based on these protocols to be extended and used with greater flexibility For the Physical Layer IEEE 802 11 utilizes non licensed ISM Industrial Scientific and Medical bands that operate between 2 4 GHz and 5 GHz In order to make wireless communication more prevalent and feasi
99. ted at the Mobile Switching Center MSC of the GSM network which then dials the number supplied by the mobile station Confirm that your cell phone service provider allows fax data type connections for your cellular service plan Please note that we are not referring to high speed wireless data services or SMS We are referring to your cellular service plan s ability to transmit a fax call connection which has been widely included in cellular service plans for years This feature is typically referred to as CSD circuit switched data p service Area op ch e CSD Summary Up to 9 6 Kbps Circuit switched connection IP based communication possible with dedicated link but speed is slow and billed by connection setup most operators remove CSD service Most GSM operators provide the service In North America CSD has been completely phased out by the end of 2007 45 A WWW moxa com info moxa com 2009 Industrial Wireless Guidebook Packet Switching Data Solution GPRS General Packet Radio Service GPRS provides Packet Switching service to GSM systems A GSM system is traditionally a Circuit Switching network that provides optimized voice transmission service For instance a call between Party A and Party B will exclude other parties Even if Party A and Party B temporarily fall into silence during their conversation the call network resource won t be released until either end hangs up As a result the netwo
100. tegrity but provides no encryption functionality On the other hand ESP provides encryption and conserves the integrity of the packet but cannot protect the outermost IP header as AH can ESP is the most commonly used protocol in a VPN because encryption is more of an important requirement in a VPN while header protection is not IPSec also contains the Internet Key Exchange protocol that is used to negotiate IPSec Connection Settings authentication endpoints and secret keys as well as to define the security parameters manage updates and more SX4JOMJ9N Je n 92 E As far as the data compression technologies go IPSec uses IP Payload Compression Protocol IPComp to compress data before encryption this also allows communication to be carried out in a more efficient way Firewall Except for data encryption using a firewall is the most common method to protect both wired and wireless connections from outside attacks There are multiple ways in which the firewall acts to deny cyber attacks including inspecting data packets for suspicious contents or filtering IP addresses The most protection a firewall can offer is to set up a list of accessible IP addresses that limits access from WANs In most M2M applications this is the most effective and direct way to protect a LAN from WAN attacks Moxa s OnCell IP router offers two kinds of firewall protection for users to choose from One way is to filter WAN IP addresses to accept or deny WAN conn
101. ternal attack As an added safeguard some manufacturers include firewall software on the access point to filter out traffic accessing the network through the AP For example Moxa s AWK 3121 supports the latest encryption technology WEP WAP WAP2 and allows system managers to filter traffic by MAC address IP as well as TCP UDP filtering options Requires a hardware upgrade JH the mew AES cipher TONNES the final 802 11i standard Most products bacinwands campais with XPA 302 1 1i WPA2 Uses today s hardware epson TF a eanas enrporates kay features of 802 11i 802 114802 11 Supported by most existing hardware Kd Sufficient security for home use Bul can be cracked in under 5 minutes C 5 Q D T e D 5 Q 5 a 5 Q c T e ES 2 c m ITI m CO O N ol 802 11 WEP WWW moxa com info moxa com Understanding Industrial WLAN IEEE 802 11 o 2 3 Antenna Theory and Selection Choosing the right antenna after a site survey is a small but important factor when planning a wireless project The purpose of this section is to explain what an antenna is and how to choose the right antenna to help build a reliable wireless network i Functions of Antennas An antenna is a transducer that is designed to transmit or receive electromagnetic waves It is like a converter that converts electromagnetic waves and electrical currents back and forth Different wirele
102. th For example the 802 11b g standards operate between 2 4 GHz and 2 4835 GHz giving a total effective bandwidth of 83 5 MHz with a channel bandwidth of 22 MHz The data rate of a particular wireless standard is the maximum data transfer speed bit per second the communication link can achieve such as 54 Mbps for 802 119 Please note that this is the specified transfer rate for raw data The WLAN protocol packages the user data with layers of headers and trailers with inter packet gaps in between the packets For example TCP communication requires the receiving end to acknowledge the received data by sending ACK packets back to the receiver Therefore the actual user data rate will be lower than the specified data rate because user data is only a portion of the raw data being transmitted via the wireless media The actual user data rate is called the throughput of the wireless link Typically we can expect the throughput to be about half of the specified data rate i e throughput 25 Mbps when data rate 54 Mbps The following figure is an example of throughput measurements as signal attenuation increases curves correspond to different noise immunity settings M 6 Deabie NP 2 46 Deable NP SG Enable NP 146 lll Grable NP 5G 4 7 10 13 16 19 22 25 2 amp 30 4 37 40 43 46 40 52 55 58 61 64 67 70 73 76 70 amp 2 ES E amp ON 94 97 DOO As you can see when the signal is too strong low attenuation or too weak
103. tive Active Ethernet I O products support Modbus TCP OPC Client Server and SNMP for greater flexibility compared to passive remote I O Proprietary Protocol Modbus TCP Yes Yes Yes Yes SNMP No Yes No No OPC Client Server Polling No Yes No Needs driver OPC Client Server Push No Yes No No 61 WWW moxa com info moxa com 2009 Industrial Wireless Guidebook General OPC servers typically use the poll response or so called pull architecture to connect to Ethernet I O devices which involves an HMI SCADA system continuously sending out commands to collect relevant data Moxa s Active OPC Server with its non polling architecture supports the standard OPC protocol but also offers active or push communication with Moxa s ioLogik series of Active Ethernet I O products to HMI SCADA systems providing instant I O status reports OPC Pull based OPC Server General OPC Server Polls continuously Local Network and Fixed IP Connection only Remote I O d Push based Active OPC Server 3 Active OPC Server Router No polling reguired Internet and Dynamic IP ioLogic Connection O D c c D rk lt O o 0 Response that s 7 Times Faster and Provides 80 off Bandwidth Usage with Event driven Tag Updates Adding additional I O channels will tend to bog down an HMI SCADA system s operation resulting Test 1 Network Traffic Comparison in a longer response time and hig
104. trical systems are integrated successfully i LL 208 333l NYIM Ieuisnpuj Guipuejsaepur E The AWK series is engineered to resist extreme vibrations and shocks based on the railway standards EN50155 EN50121 3 2 50121 4 Rail Traffic EN 50155 Environmental EN 50121 3 2 EMC EN 50121 4 EMC WWW moxa com info moxa com 42 43 Understanding Industrial WLAN IEEE 802 11 9 i ATEX Class I Division 2 ATEX is the term used when referring to the European Unions EU Directive 94 9 EC ATEX governs the regulations on the equipment used in potentially explosive atmospheres All equipment meeting the requirements are free to circulate within EU boarders The directive applies to all equipment or protective systems used in areas subject to explosion risks gas vapors mist or dust The directive also sets the standards for safety devices control equipment and calibration equipment About ATEX Class Division 2 Class Division 2 Zone 2 Class Locations These locations are defined as places where the air may contain flammable gases or vapors in sufficient quantities to cause explosive or ignitable mixtures Division 2 The division defines the conditions under which the hazard exists Division 2 refers to the following conditions e Liquids and gases in closed containers or systems are handled processed or used e Concentrations are normally prevented by positive mechanical ventilation e The specified
105. vide a new interface IOPCServerList that can be marshaled and used by remote clients This server has a published classid see below and can be installed once on any machine which hosts OPC servers The client still needs to know the nodename of the target machine however he can now create this object remotely and use its IOPCServerList interface to determine what types and brands of servers are available on that machine WWW moxa com infogmoxa com 64 Cellular Networks o i OPC and DCOM 5 Things You Need to Know OPC technology relies on Microsoft s COM and DCOM to exchange data between automation hardware and software however it can be frustrating for new users to configure DCOM properly If you have ever been unable to establish an OPC connection or transfer OPC data successfully the underlying issue is likely DCOM related In the following we will discuss the steps necessary to get DCOM working properly and securely A simple and effective strategy to establish reliable DCOM communication involves the following steps Remove Windows Security The first step to establish DCOM communication is to disable the Windows Firewall which is turned on by default in Windows XP Service Pack 2 and later The Firewall helps protect computers from unauthorized access usually from viruses worms and people with malicious or negligent intents If the computer resides on a safe network there is usually little potential for damage as long as the Fi
106. ware to transfer and receive data from the serial devices Here s how it works e Installing OnCell Driver Manager onto the host PC allows the host PC to connect directly to remote serial device e The serial device is connected to the OnCell G3100 s serial port e The connection is maintained automatically between OnCell Driver Manager and the OnCell G3100 device to access the serial device over a cellular network WWW moxa com info moxa com 2009 Industrial Wireless Guidebook e Depending on whether the OnCell G3100 device is acting in a Client role or Server role the user can select Real COM mode or Reverse Real COM mode Normally the role of the OnCell G3100 device depends on the IP address obtained from your cellular service provider If your OnCell G3100 device s SIM card is able to obtain a public IP address then the OnCell device can act as a Server and you can select Real COM mode to connect the host PC Client role OnCell Device s IP Address Suitable Role Operation Mode Selection Public address Client role Reverse Real COM mode Private IP vale tadorn Client role Reverse Real COM mode Like 10 x y x or 172 xx If both the host PC at the control center and the OnCell G3100 device have private IP addresses you can use Real COM mode on the OnCell G3100 to resolve the private IP to private IP problem Real COM mode diagram 2 9 pevic B5 x Q D c c
107. xa s proprietary Wireless Bridge System Dual RF allows several buildings on a corporate campus to be connected to the central office The central AP is configured as the master device and the remote client stations as slave devices The wireless link will not reduce the bandwidth to due to the use of Dual RF and isolation of the overlap frequency channel but will extend the wireless range LL 208 333l NYIM Ieuisnpuj Guipuejsaepur WWW moxa com info moxa com 24 Understanding Industrial WLAN IEEE 802 11 9 i Components of the Expanded 802 11 Wireless System Expanded 802 11 wireless systems consist of the following components some of which are optional Access Points Moxa supplies 802 11a b g n 802 11n will be implemented in the future the technology works by using multiple antennas to target one or more sources to increase transmission power and throughput wireless AP Bridge Client devices to extend the wireless range IEEE 802 11a is a modified version of the IEEE 802 11 standard and was approved in 1999 IEEE 802 11a adopts the same standards as IEEE 802 11 and operates in the 5 GHz band It uses 52 Orthogonal Freguency Division Multiplexing OFDM waves and has a maximum capacity of 54 Mbps This has already satisfied the standard reguirement of network communication which needs around 20 Mbps of bandwidth It is also possible to drop the communication speed to 48 36 24 18 12 9 or even 6 Mbps IEEE 802
108. y It is therefore reasonable that cellular network operators issue private and dynamic IP addresses to conserve valuable public IP resources 2 The bandwidth of a cellular network is so narrow that it is very vulnerable to cyber attack Private IP effectively prevents cyber attacks from paralyzing the networks 3 Require only uplink from cellular device to WLAN However in most M2M applications it is a requirement that data exchange is a two way communication either from server to client or client to server To solve this private IP issue for M2M applications three major solutions are available 1 Users can pay extra money to get a public and fixed IP SIM card This way cellular M2M system configuration will be very similar to LAN architecture 2 Users can get cellular VPN services from their ISP Internet Service Provider or a second tier operator known as an MVNO Mobile Virtual Network Operator They offer services to allow cellular links between nodes in a VPN that uses open connections or virtual circuits in a larger network such as the Internet With the help of VPNs cellular devices act as a VPN client that can initiate a connection with a VPN server building a two way communication environment for M2M applications 3 Despite VPN being the most commonly seen solution to the private IP problem in M2M applications the data exchange inside a VPN can take up too much of the network resources for it requires heavy duty encryption a
109. y and highly specialized technical support for a diverse range of applications including connecting PLCs to n L PI Sg Moxa Inc www moxa com info moxa com cus t Moxa Americas Toll free 1 888 MOXA USA 1 888 669 2872 Tel 1 714 528 6777 Fax 1 714 528 6778 www moxa com usaQmoxa com Moxa Europe Tel 49 89 3 70 03 99 0 Fax 49 89 3 70 03 99 99 www moxa com europe moxa com Moxa Asia Pacific Tel 886 2 8919 1230 Fax 886 2 8919 1231 www moxa com asia moxa com gt Ce FE a wireless control network transmitting temperature signals over long distances and automating device control monitoring at remote locations Moxa China Shanghai Office Tel 86 21 5258 9955 Fax 86 21 5258 5505 www moxa com cn china moxa com Beijing Office Tel 86 10 6872 3959 60 61 Fax 86 10 6872 3958 WWW moxa com cn China moxa com Shenzhen Office Tel 86 755 8368 4084 94 Fax 86 755 8368 4148 www moxa com cn china moxa com Trademark Credits The Moxa Inc logo is a registered trademark of Moxa Inc All other trademarks mentioned in this document are the property of their respective owners 2009 Moxa Inc All rights reserved The MOXA logo is a registered trademark of Moxa Inc All other logos appearing in this document are the intellectual property of the respective company product or organization associated with the logo P N 1900040901050

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