Racom RA400-432 UHF NARROWBAND RADIOMODEM User Manual navod RipEX new a

Racom UHF NARROWBAND RADIOMODEM navod RipEX new a

Users Manual

User manual.RipEXRadio modem & Router.version 1.35/31/2012fw 1.1.4.0www.racom.euRACOM s.r.o. • Mirova 1283 • 592 31 Nove Mesto na Morave • Czech RepublicTel.: +420 565 659 511 • Fax: +420 565 659 512 • E-mail: racom@racom.eu
Table of ContentsGetting started ..................................................................................................................................... 71. RipEX – Radio router ...................................................................................................................... 91.1. Introduction ........................................................................................................................... 91.2. Key Features ........................................................................................................................ 91.3. Standards ........................................................................................................................... 102. RipEX in detail ............................................................................................................................... 122.1. Modes of operation ............................................................................................................. 122.2. Bridge mode ....................................................................................................................... 122.3. Router mode ....................................................................................................................... 172.4. Serial SCADA protocols ..................................................................................................... 222.5. Combination of IP and serial communication ..................................................................... 232.6. Diagnostics & network management .................................................................................. 232.7. Firmware update and upgrade ........................................................................................... 252.8. Software feature keys ......................................................................................................... 253. Network planning ........................................................................................................................... 273.1. Data throughput, response time ......................................................................................... 273.2. Frequency .......................................................................................................................... 283.3. Signal budget ..................................................................................................................... 293.4. Multipath propagation, DQ ................................................................................................. 303.5. Network layout .................................................................................................................... 333.6. Hybrid networks .................................................................................................................. 353.7. Assorted practical comments ............................................................................................. 354. Product .......................................................................................................................................... 374.1. Dimensions ......................................................................................................................... 374.2. Connectors ......................................................................................................................... 384.3. Indication LEDs .................................................................................................................. 434.4. Technical specification ........................................................................................................ 444.5. Model offerings ................................................................................................................... 524.6. Accessories ........................................................................................................................ 535. Bench test ..................................................................................................................................... 565.1. Connecting the hardware ................................................................................................... 565.2. Powering up your RipEX .................................................................................................... 565.3. Connecting RipEX to a programming PC ........................................................................... 565.4. Basic setup ......................................................................................................................... 605.5. Functional test .................................................................................................................... 606. Installation ..................................................................................................................................... 616.1. Mounting ............................................................................................................................. 616.2. Antenna mounting .............................................................................................................. 646.3. Antenna feed line ............................................................................................................... 646.4. Grounding ........................................................................................................................... 656.5. Connectors ......................................................................................................................... 656.6. Power supply ...................................................................................................................... 657. Advanced Configuration ................................................................................................................ 667.1. Menu header ...................................................................................................................... 667.2. Status ................................................................................................................................. 677.3. Settings ............................................................................................................................... 687.4. Routing ............................................................................................................................... 987.5. Diagnostic ......................................................................................................................... 1007.6. Maintenance ..................................................................................................................... 1138. CLI Configuration ........................................................................................................................ 1179. Troubleshooting ........................................................................................................................... 1183© RACOM s.r.o. – RipEX Radio modem & Router
10. Safety, environment, licensing ................................................................................................... 12010.1. Frequency ...................................................................................................................... 12010.2. Safety distance ............................................................................................................... 12010.3. High temperature ............................................................................................................ 12510.4. RoHS and WEEE compliance ........................................................................................ 12510.5. Conditions of Liability for Defects and Instructions for Safe Operation of Equipment .... 12610.6. Important Notifications .................................................................................................... 12610.7. Product Conformity ......................................................................................................... 127A. Abbreviations .............................................................................................................................. 129Index ................................................................................................................................................ 131B. Revision History .......................................................................................................................... 133List of Figures1. RipEX radio router ........................................................................................................................... 72.1. Bridge mode example ................................................................................................................ 152.2. Addressing ................................................................................................................................. 202.3. Optimised addressing ................................................................................................................. 212.4. Monitoring ................................................................................................................................... 253.1. Application bench test ................................................................................................................ 283.2. Signal path ................................................................................................................................. 293.3. Multipath propagation ................................................................................................................. 313.4. Antenna location ......................................................................................................................... 323.5. Main lobe .................................................................................................................................... 333.6. Dominant repeater ...................................................................................................................... 343.7. Isolated branches ....................................................................................................................... 343.8. Antenna mounting ...................................................................................................................... 364.1. RipEX dimensions, see more ..................................................................................................... 374.2. L-bracket and Flat-bracket, see more ........................................................................................ 374.3. Connectors ................................................................................................................................. 384.4. Antenna connector TNC ............................................................................................................. 384.5. Separated Rx and TX antennas ................................................................................................. 394.6. Supply connector ........................................................................................................................ 404.7. Power and Control - cable plug .................................................................................................. 404.8. RJ-45F ........................................................................................................................................ 414.9. Serial connector ......................................................................................................................... 414.10. Serial connector ....................................................................................................................... 424.11. Reset ........................................................................................................................................ 424.12. GPS Connector SMA ............................................................................................................... 424.13. Indication LEDs ........................................................................................................................ 434.14. Part Number ............................................................................................................................. 524.15. Assembly dimensions with fan ................................................................................................. 534.16. Dummy load ............................................................................................................................. 534.17. L-bracket .................................................................................................................................. 534.18. Flat bracket ............................................................................................................................... 544.19. 19" Rack shelf .......................................................................................................................... 544.20. X5 adapter ETH/USB ............................................................................................................... 544.21. Demo case ............................................................................................................................... 555.1. Bench test .................................................................................................................................. 565.2. Connecting to a PC over ETH and over ETH/USB adapter ....................................................... 575.3. PC address setting ..................................................................................................................... 585.4. Authentication ............................................................................................................................. 59RipEX Radio modem & Router – © RACOM s.r.o.4RipEXRadio modem & Router
5.5. Status Menu ............................................................................................................................... 596.1. Flat lengthwise mounting to DIN rail – recommended ............................................................... 616.2. Flat widthwise mounting to DIN rail ............................................................................................ 616.3. Vertical widthwise mounting to DIN rail ...................................................................................... 626.4. Vertical lengthwise mounting to DIN rail ..................................................................................... 626.5. Flat mounting using Flat bracket ................................................................................................ 626.6. Rack shelf ................................................................................................................................... 636.7. Fan kit mounting ......................................................................................................................... 636.8. Fan kit using Alarm Output, recommended ................................................................................ 646.9. Fan kit, always on ....................................................................................................................... 646.10. 10–30 VDC Supplying .............................................................................................................. 657.1. Menu Header .............................................................................................................................. 667.2. Menu Status ............................................................................................................................... 677.3. Menu Settings ............................................................................................................................ 687.4. Menu Alarm management .......................................................................................................... 737.5. Menu Radio ................................................................................................................................ 767.6. Menu Ethernet ............................................................................................................................ 797.7. Menu COM ................................................................................................................................. 847.8. Menu Protocols COM ................................................................................................................. 867.9. Menu Routing ............................................................................................................................. 987.10. Menu Neighbours ................................................................................................................... 1007.11. Menu Statistic ......................................................................................................................... 1037.12. Menu Graphs .......................................................................................................................... 1047.13. Menu Ping .............................................................................................................................. 1057.14. Menu Monitoring ..................................................................................................................... 1097.15. Monitoring ............................................................................................................................... 1137.16. Menu SW feature keys ........................................................................................................... 1137.17. Menu Maintenance Configuration .......................................................................................... 1147.18. Menu Maintenance Firmware ................................................................................................. 1157.19. Menu Maintenance Password ................................................................................................ 1157.20. Menu Maintenance Configuration .......................................................................................... 11610.1. RipEX consistency declaration ............................................................................................... 128List of Tables4.1. Pin assignement ......................................................................................................................... 394.2. Ethernet to cable connector connections ................................................................................... 414.3. COM1,2 pin description .............................................................................................................. 414.4. USB pin description .................................................................................................................... 424.5. Key to LEDs ............................................................................................................................... 434.6. Technical parameters ................................................................................................................. 444.7. Channel spacing 25 kHz, exponential modulation, CE .............................................................. 474.8. Channel spacing 25 kHz, linear modulation, CE ........................................................................ 474.9. Channel spacing 12,5 kHz, exponential modulation, CE ........................................................... 484.10. Channel spacing 12,5 kHz, linear modulation, CE ................................................................... 484.11. Channel spacing 25 kHz, exponential modulation, FCC .......................................................... 494.12. Channel spacing 25 kHz, linear modulation, FCC ................................................................... 494.13. Channel spacing 12,5 kHz, exponential modulation, FCC ....................................................... 504.14. Channel spacing 12,5 kHz, linear modulation, FCC ................................................................ 504.15. Channel spacing 6,25 kHz, exponential modulation, FCC ....................................................... 514.16. Channel spacing 6,25 kHz, linear modulation, FCC ................................................................ 5110.1. Minimum Safety Distance 160 MHz ....................................................................................... 1205© RACOM s.r.o. – RipEX Radio modem & RouterRipEXRadio modem & Router
10.2. Minimum Safety Distance 300–400 MHz ............................................................................... 122RipEX Radio modem & Router – © RACOM s.r.o.6RipEXRadio modem & Router
Getting startedRipEX is a widely configurable compact radio modem, more precisely a radio IP router. All you haveto do to put it into operation is to connect it to an antenna and a power supply and configure it using aPC and a web browser.Antenna IndicatorLEDs' SleepInputAlarmInput-GND+AlarmOutput+Supply+10to+30V-GNDEthernet USBCOM1RS232COM2RS232/485Default/Reset--++SI AIAO10–30VDCETH USBANTCOM1COM2Fig. 1: RipEX radio routerRipEX access defaults: IP 192.168.169.169/24, username: admin, password: adminSet a static IP 192.168.169.x/24 on your PC, power on the RipEX and wait 25 seconds for the RipEXOS to boot. Connect your PC to RipEXs' ETH interface, start your browser and type ht-tps://192.168.169.169 in the address line. When accessing RipEX for the first time, you have to acceptthe https security certificate issued by Racom.Before attempting to do any configuration, make sure your RipEX is the only powered-up unit around.Since all units coming from factory share the same default settings ex factory, you could be accessinga different unit over the air without being aware of it.When accessing over the optional “X5” USB/ETH adapter, your PC will get its IP settings from the built-in DHCP server and you have to type https://10.9.8.7 in your browser. Remaining steps are the sameand you do not need to worry about other RipEX's, you will be connected to the local unit in all cases.SCADA radio network step-by-stepBuilding a reliable radio network for a SCADA system may not be that simple, even when you use sucha versatile and easy-to-operate device as the RipEX radio modem. The following step-by-step checklistcan help you to keep this process fast and efficient.1. Design your network to ensure RF signal levels meet system requirements.2. Calculate and estimate the network throughput and response times when loaded by your application.3. Perform a bench-test with 3-5 sets of RipEX's and SCADA equipment (Chapter 5, Bench test).4. Design the addressing and routing scheme of the network (Chapter 2, RipEX in detail and RipEXApp notes, Address planing1)5. Preconfigure all RipEX's (Section 5.4, “Basic setup”).6. Install individual sites1. Mount RipEX into cabinet (Section 6.1, “Mounting”).1http://www.racom.eu/eng/products/m/ripex/app/routing.html7© RACOM s.r.o. – RipEX Radio modem & RouterGetting started
2. Install antenna (Section 6.2, “Antenna mounting”).3. Install feed line (Section 6.3, “Antenna feed line”).4. Ensure proper grounding (Section 6.4, “Grounding”).5. Run cables and plug-in all connectors except from the SCADA equipment (Section 4.2,“Connectors”)6. Apply power supply to RipEX7. Test radio link quality (Section 5.5, “Functional test”).8. Check routing by the ping tool (the section called “Ping”) to verify accessibility of all IP ad-dresses with which the unit will communicate.9. Connect the SCADA equipment7. Test your applicationRipEX Radio modem & Router – © RACOM s.r.o.8Getting started
1. RipEX – Radio router1.1. IntroductionRipEX is a best-in-class radio modem, not only in terms of data transfer speed. This Software DefinedRadio with Linux OS has been designed with attention to detail, performance and quality. All relevantstate-of-the-art concepts have been carefully implemented.RipEX provides 24x7 reliable service for mission-critical applications like SCADA & Telemetry for Util-ities, SmartGrid power networks or transaction networks connecting lottery terminals, POS or ATM’s.Any unit can serve as the central master, repeater, remote terminal, or all of these simultaneously, witha configuration interface easily accessible from a web browser.Anybody with even basic knowledge of IP networking can set up a RipEX within a matter of minutesand maintain the network quite easily.1.2. Key Features• Exceptional data speeds on the radio channel- 83 kbps / 25 kHz, 42 kbps / 12.5 kHz, 21 kbps / 6.25 kHz• 1× ETH, 2× COM, 1× USB, 5× virtual COM- Simultaneously on radio channel. COM1-RS232, COM2-RS232 or RS485, software configurable.Virtual COMs over ETH controlled by Terminal servers. USB for independent service access viaUSB/ETH adapter.• 135–175; 300–370; 368–470; 928–960 MHz- Licensed radio bands- Software-selectable channel spacing 25, 12.5 or 6.25 kHz• 10 watts- Transmission output control, nine stages from 0.1 to 10 W (max. 2 W for linear modulations).• Energy saving- Sleep mode – 0.1 W, controlled via a digital input.Save mode – 2.3 W, wake up by receiving a packet from the radio channel• Extended temperature range−40 to +70 ºC• Easy to configure and maintain- Web interface,- Wizards,- On-line help,- Balloon tips,- Fastest web access to remote units• Bridge or Router- RipEX is a device with native IP support which can be set as a standard bridge or router.9© RACOM s.r.o. – RipEX Radio modem & RouterRipEX – Radio router
• Modbus, IEC101, DNP3, Comli, RP570, C24, DF1, Profibus, Modbus TCP, IEC104, DNP3 TCPetc.- Unique implementation of industrial protocols enables a secure addressed transmission of allpackets in all directions• Anti-collision protocol on radio channel- Allows multi polling & report-by-exception concurrently for several independent applications sim-ultaneously• Optimization – 3× higher throughput- Optimisation method which joins short packets, compresses data, optimises both the traffic to thelink peer and the sharing of the radio channel capacity among the links.• Embedded diagnostic & NMS- Real time and historical (20 periods, e.g. days) statistics and graphs for the unit and its neighbours.- SNMP including generation of TRAP alarms when preset thresholds are exceeded- on-line/off-line (recorded to a file in the RipEX) monitoring of all interfaces• 256 AES encryption- The most secure encryption meets FIPS 140 2 requirements• Pay only for what you need- Software authorisation keys allow you to add advanced features when needed (Router mode, 83kbps, COM2, 10 W)- Free Master-key trial – (all coded features) for 30 days in every RipEX• Reliability- 3 years warranty, rugged die cast aluminium case, military or industrial components- Every single unit tested in a climatic chamber as well as in real traffic1.3. StandardsETSI EN 300 113-2RadioETSI EN 302 561ETSI EN 301 166-2FCC part 90ETSI EN 301 489-1EMCETSI EN 301 489-5ETSI EN 301 489-5EN 61000-3-2EN 61000-3-3EN 60 950-1SafetyEN 61 373VibrationIEEE 802.3iETHIEEE 802.3uIEEE 802.3afRipEX Radio modem & Router – © RACOM s.r.o.10RipEX – Radio router
EIA-232-FRS232EIA RS-485RS485IEC 60870-5-101IEC101IEC 60870-5-104IEC104IEEE 1815-2010DNP3IEC 61158 Type 3Profibus DP-V011© RACOM s.r.o. – RipEX Radio modem & RouterRipEX – Radio router
2. RipEX in detail2.1. Modes of operationRadio modem RipEX is best suited for transmission of a large number of short messages where aguaranteed delivery time is required, i.e. for mission critical applications.RipEX has the following basic uses:• PollingIn poll-response networks a central master unit communicates with a number of remote radiomodemsone at a time. The master unit exchanges data with the currently connected remote radio, and whenfinished, it establishes a new connection with the next remote radio according to the polling order.• Report-by-exceptionIn report-by-exception networks remote units can be contacted similarly to polling networks. In ad-dition, any remote unit can spontaneously send data to the master unit (typically an alarm).• MeshIn mesh type networks any radio modem in the network can access any other radio modem randomlyand spontaneously. Mesh network can also host polling or report-by-exception applications, evenin several instances.2.2. Bridge modeA packet received through any interface is broadcast to the appropriate interfaces of all units within thenetwork. Packets received on COM are broadcast to both COM1 and COM2 at remote sites, allowingyou to connect 2 RTU's to any radio modem.Any unit can be configured as a repeater. A repeater relays all packets it receives through the radiochannel. The network implements safety mechanisms which prevent cyclic loops in the radio channel(e.g. when a repeater receives a packet from another repeater) or duplicate packets delivered to theuser interface (e.g. when RipEX receives a packet directly and then from a repeater).Beside standard packet termination by an "Idle" period on the serial port (a pause between receivedbytes) the bridge mode also offers "streaming". While in streaming mode, transmission on the radiochannel starts immediately, without waiting for the end of the received frame on COM => zero latency.The bridge mode is suitable for all polling applications.2.2.1. Detailed DescriptionBridge mode is suitable for Point-to-Multipoint networks, where Master-Slave applications with polling-type communication protocol are used. RipEX in bridge mode is as easy to use as a simple transparentdevice, while providing communication reliability and spectrum efficiency by employing a sophisticatedprotocol in the radio channel.In bridge mode, the radio channel protocol do not solve collisions. There is a CRC check of data integrity,however, i.e. once a message is delivered, it is 100% error free.RipEX Radio modem & Router – © RACOM s.r.o.12RipEX in detail
All the messages received from user interfaces (ETH&COM's) are immediately transmitted to the radiochannel.ETH - The whole network of RipEX radiomodems behaves as a standard ethernet network bridge.Each ETH interface automatically learns which devices (MAC addresses) are located in the local LANand which devices are accessible over the radio channel. Consequently, only the ethernet frames ad-dressed to remote devices are physically transmitted on the radio channel. This arrangement savesthe precious RF spectrum from extra load which would be otherwise generated by local traffic in theLAN (the LAN to which the respective ETH interface is connected).COM1,COM2 - All frames received from COM1(2) are broadcast over the radio channel and transmittedto all COM's (COM1 as well as COM2) on all radio modems within the network, the other COM on thesource RipEX excluding.There is a special parameter TX delay (Adv. Config., Device), which should be used when all substations(RTU's) reply to a broadcast query from the master station. In such case massive collisions would ensuebecause all substations (RTU's) would reply at nearly the same time. To prevent such collision, TXdelay should be set individually in each slave RipEX. The length of responding frame, the length ofradio protocol overhead, modulation rate have to be taken into account.2.2.2. Functionality exampleIn the following, common acronyms from SCADA systems are used:• FEP - Front End Processor, designates the communication interface equipment in the centre• RTU - Remote Telemetry Unit, the terminal SCADA equipment at remote sitesThe single digits in illustrations are “site names” and do not necessarily correspond with actual addressesof both the RipEX's and SCADA equipment. Address configuration examples are given in the nextchapter.Step 1Polling cycle starts:FEP sends a request packet for RTU3 through COM1 tothe connected RipEX.Step 2FEP’s RipEX broadcasts this packet on Radio channel.RipEX3 and RipEX1 receive this packet.RipEX2 doesn’t receive this packet, because it is not withinradio coverage of FEP’s RipEX.13© RACOM s.r.o. – RipEX Radio modem & RouterRipEX in detail
Step 3RipEX3 and RipEX1 send the received packet to theirCOM1 and COM2.Packet is addressed to RTU3, so only RTU3 responds.RipEX1 is set as a repeater, so it retransmits the packeton Radio channel. Packet is received by all RipEXes.Step 4RipEX2 sends repeated packet to its COM1 and COM2.RTU2 doesn’t react, because the packet is addressed toRTU3.RipEX3 and FEP’s RipEX do not send the repeatedpacket to their COM ports, because it has already beensent (RipEX3) or received (FEP’s RipEX) on their COM(anti-duplication mechanism).RTU3 sends the reply packet.Step 5RipEX3 broadcasts the reply packet from RTU3 on Radiochannel.Packet is received by RipEX1 and FEP’s RipEX.Step 6FEP’s RipEX sends the packet (the reply from RTU3) toFEP through COM1.RipEX1 sends this packet to RTU1. RTU1 doesn’t react,because the packet is addressed to FEP.RipEX1 repeats the packet on Radio channel.All RipEXes receive the packet.Step 7RipEX2 sends repeated packet to its COM1 and COM2.RTU2 doesn’t react, because the packet is addressed toFEP.RipEX3 and FEP’s RipEXes do not send the repeatedpacket to their COM ports, because it has been handledalready.FEP processes the reply from RTU3 and polling cyclecontinues…..RipEX Radio modem & Router – © RACOM s.r.o.14RipEX in detail
2.2.3. Configuration examplesYou can see an example of IP addresses of the SCADA equipment and RipEX's ETH interfaces in thepicture below.In Bridge mode, the IP address of the ETH interface of RipEX is not relevant for user data communic-ation. However it is strongly recommended to assign a unique IP address to each RipEXs' ETH interface,since it allows for easy local as well as remote service access. Moreover, leaving all RipEX's with thesame (= default) IP on the ETH interface may cause serious problems, when more RipEX's are con-nected to the samX5e LAN, even if by accident (e.g. during maintenance).192.168.5.51/24192.168.5.50/24192.168.5.12/24192.168.5.2/24192.168.5.3/24192.168.5.11/24192.168.5.1/24192.168.5.13/24 3FEP5012REPEATERFig. 2.1: Bridge mode exampleRepeaterBecause using the bridge mode makes the network transparent, the use of repeaters has certain limit-ations. To keep matters simple we recommend using a single repeater. However, if certain rules areobserved, using multiple repeaters in the same network is possible.The total number of repeaters in the network is configured for every unit individually under Bridge modeparameters. This information is contained in every packet sent. All units that receive such packet willresume transmission only after sufficient time has been allowed for the packet to be repeated. Thepackets received from user ports remain buffered and are sent after the appropriate time passes. Thisprevents collisions between remote radio modems. There can be no repeater collisions if only one re-peater is used.15© RACOM s.r.o. – RipEX Radio modem & RouterRipEX in detail
Where two or more repeaters are used, collisions resulting from simultaneous reception of a repeatedpacket must be eliminated. Collisions happen because repeaters repeat packets immediately after re-ception, i.e. if two repeaters receive a packet from the centre, they both relay it at the same time. Ifthere is a radiomodem which is within the range of both repeaters, it receives both repeated packetsat the same time rendering them unreadable.Examples:1. Repeaters connected seriallyA packet is transmitted and repeatedin steps 1, 2, 3.Centre RPT1 RPT2 Remote1 2 3In improperly designed networks collisions happenif a remote radio modem lies in the range of twoXCOLLISION!1122WRONGCEN RPT1 RPT2 REMrepeaters (see the image): the packet sent fromthe centre (1) is received by both repeaters. It isrepeated by them both (2) causing a collision atthe remote. In other words – there should not bemore than one repeater where the centre and re-motes' coverage areas overlap.Solution 1.Adjust signal coverage so that RPT2 is out of rangeof the centre and RPT1 is out of the range of theGOODCoveragearea123CEN RPT1 RPT2 REMremote radio modem. This can be achieved forexample by reducing the output power or using aunidirectional antenna.Solution 2.Use a single repeater. (Whenever network layoutallows that.)12GoodCEN RPT1 REMRipEX Radio modem & Router – © RACOM s.r.o.16RipEX in detail
2. Parallel repeatersImproperly designed network:CentreRepeater1Remote11212Remote2Repeater2XCOLLISION!GOODWRONG1212CENCENRPT1RPT1REM1REM11212REM2REM2RPT2RPT22- RipEX REM1 is within the rangeof two repeaters (RPT1 and RPT2).The repeaters receive a packet (1)from the centre (CEN) and repeatit at the same time (2) causing acollision at REM1.Well-designed network:- A remote is only in the range of asingle repeater (REM1-RPT1,REM2-RPT2).There is always only one repeaterwhere the centre and remote cov-erage areas overlap.2.3. Router modeRipEX works as a standard IP router with two interfaces (radio and ethernet) and two COM port devices.There is a sophisticated anti-collision protocol on the radio channel, which checks and verifies everysingle packet. Being an IP router, each unit can simultaneously work as a store-and-forward repeaterand deliver packets to the connected equipment.The router mode is suitable for all uses. In contrast to the bridge mode, a packet reception is confirmedover the radio channel even in very simple polling type applications, and if necessary the packet is re-transmitted.2.3.1. Detailed DescriptionRouter mode is suitable for multipoint networks, where multi-master applications with any combinationof polling and/or spontaneous data protocols can be used. The proprietary link-layer protocol on theradio channel is very sophisticated, it can transmit both unicast and broadcast frames, it has collisionavoidance capability, it uses frame acknowledgement, retransmissions and CRC checks to guaranteedata delivery and integrity even under harsh interference conditions on the radio channel.RipEX works as a standard IP router with 2 independent interfaces: radio and ETH. Each interface hasits own MAC address, IP address and mask.IP packets are processed according the routing table rules. You can also set the router’s default gateway(applies to both interfaces) in the routing table.The COM ports are treated as standard host devices, messages can be delivered to them as UDPdatagrams to selected port numbers. The destination IP address of a COM port is either the IP of ETHor the IP of a radio interface. The source IP address of outgoing packets from COM ports is always theIP of the ETH interface.17© RACOM s.r.o. – RipEX Radio modem & RouterRipEX in detail
2.3.2. Functionality exampleIn the following example, there are two independent SCADA devices connected to RipEX's two COMports. One is designated RTU (Remote Telemetry Unit) and is assumed to be polled from the centreby the FEP (Front End Processor). The other is labelled PLC (Programmable Logic Controller) and isassumed to communicate spontaneously with arbitrary chosen peer PLCs.Step 1FEP sends a request packet for RTU1 through COM2 toits connected RipEX.Simultaneously PLC2 sends a packet for PLC1 to RipEX2through COM1.Step 2FEP’s RipEX transmits an addressed packet for RTU1 onRadio channel.RipEX1 receives this packet, checks data integrity andtransmits the acknowledgement.At the same time packet is sent to RTU1 through COM2.RipEX3 receives this packet too. It doesn’t react, becausethis packet is directed to RipEX1 only.Step 3RipEX2 waits till previous transaction on Radio channel isfinished (anti-collision mechanism).Then RipEX2 transmits on Radio channel the addressedpacket for PLC1.RipEX1 receives this packet, checks data integrity andtransmits acknowledgement.At the same time packet is sent to PLC1 through COM1.Simultaneously the reply packet from RTU1 for FEP is re-ceived on COM2.Step 4RipEX1 transmitts the reply packet from RTU1 for FEP onRadio channel.All RipEXes receive this packet. This packet is addressedto FEP’s RipEX, so only FEP’s RipEX reacts. It checksdata integrity and transmits the acknowledgement toRipEX1.At the same time the packet is sent to FEP through COM2.RipEX Radio modem & Router – © RACOM s.r.o.18RipEX in detail
Step 5FEP receives the response from RTU1 and polling cyclecontinues…However any PLC or RTU can spontaneously send apacket to any destination anytime.2.3.3. Configuration examplesAs it was mentioned above, RipEX radiomodem works as a standard IP router with two independentinterfaces: radio and ETH. Each interface has got its own MAC address, IP address and mask.The IP router operating principles stipulate that every unit can serve as a repeater.. Everything whatis needed is the proper configuration of routing tables.Radio IP addresses of the RipEX’s required to communicate over the radio channel must share thesame IP network. We recommend planning your IP network so that every RipEX is connected to aseparate sub-network over the ethernet port. This helps to keep the routing tables clear and simple.NoteEven if the IP addresses of all RipEXes in a radio channel share a single IP network, theymay not be communicating directly as in a common IP network. Only the RipEXes that arewithin the radio range of each other can communicate directly. When communication withradio IP addresses is required, routing tables must include even the routes that are withinthe same network (over repeaters), which is different from common IP networks. The exampleconfiguration below does not show such routing rules for the sake of simplicity (they are notneeded in most cases).19© RACOM s.r.o. – RipEX Radio modem & RouterRipEX in detail
10.10.10.50/24192.168.50.2/24RoutingtableRipEX50:192.168.1.0/24 10.10.10.1192.168.2.0/24 10.10.10.1192.168.3.0/24 10.10.10.3DefaultGW192.168.50.2èèè192.168.2.2/24Routingtable :192.168.1.0/24 10.10.10.1RipEX2192.168.50.0/24 10.10.10.1192.168.3.0/24 10.10.10.1èèè10.10.10.3/24192.168.3.2/24RoutingtableRipEX3:192.168.50.0/24 10.10.10.50192.168.1.0/24 10.10.10.50192.168.2.0/24 10.10.10.50èèè10.10.10.1/24192.168.1.1/24192.168.1.2/24Routingtable :192.168.2.0/24 10.10.10.2RipEX1192.168.50.0/24 10.10.10.50192.168.3.0/24 10.10.10.50èèè192.168.3.1/24 350FEP1192.168.50.1/24RadioIPETHIPFEP IP10.10.10.2/242192.168.2.1/24Fig. 2.2: AddressingFormal consistency between the last byte of the radio IP address and the penultimate byte of the eth-ernet address is not necessary but simplifies orientation. The “Addressing” image shows a routing tablenext to every RipEX. The routing table defines the next gateway for each IP destination. In radiotransmission, the radio IP of the next radio-connected RipEX serves as the gateway.Example of a route from FEP (RipEX 50) to RTU 2:• The destination address is 192.168.2.2• The routing table of the RipEX 50 contains this record:Destination 192.168.2.0/24 Gateway 10.10.10.1• Based on this record, all packets with addresses in the range from 192.168.2.1 to 192.168.2.254are routed to 10.10.10.1• Because RipEX 50’s radio IP is 10.10.10.50/24, the router can tell that the IP 10.10.10.1 belongsto the radio channel and sends the packet to that address over the radio channel• The packet is received by RipEX 1 with the address 10.10.10.1 where it enters the router• The routing table of RipEX 1 contains the record:Destination 192.168.2.0/24 Gateway 10.10.10.2based on which the packet is routed to 10.10.10.2 over the radio channel• The packet is received by RipEX 2• The router compares the destination IP 192.168.2.2 with its own ethernet address 192.168.2.1/24and determines that the packet’s destination is within its ETH network and sends the packet overthe ethernet interface – eventually, the packet is received by RTU 2.RipEX Radio modem & Router – © RACOM s.r.o.20RipEX in detail
2.3.4. Addressing hintsIn large and complex networks with numerous repeaters, individual routing tables may become longand difficult to comprehend. To keep the routing tables simple, the addressing scheme should followthe layout of the radio network.More specifically, every group of IP addresses of devices (both RipEX's and SCADA), which is accessedvia a repeater, should fall in a range which can be defined by a mask and no address defined by thatmask exists in different part of the network.A typical network consisting of a single centre and number of remotes has got a tree-like layout, whichcan be easily followed by the addressing scheme – see the example in the Figure Optimised addressingbelow.10.10.10.50/24192.168.50.2/24RoutingtableRipEX50:192.168.0.0/22 10.10.10.1192.168.4.0/22 10.10.10.4DefaultGW192.168.50.2èè10.10.10.2/24192.168.2.1/24192.168.2.2/24Routingtable :192.168.0.0/16 10.10.10.1RipEX2è10.10.10.4/24192.168.4.2/24RoutingtableRipEX4:192.168.0.0/16 10.10.10.50è10.10.10.1/24192.168.1.1/24192.168.1.2/24Routingtable :192.168.2.0/24 10.10.10.2RipEX1192.168.0.0/16 10.10.10.50èè192.168.4.1/24 450FEP12RadioIPETHIPFEP IP192.168.50.1/24Fig. 2.3: Optimised addressingThe default gateway is also a very powerful routing tool, however be very careful whenever the defaultroute would go to the radio interface, i.e. to the radio channel. If a packet to non-existing IP destinationcame to the router, it would be transmitted over the radio channel. Such packets increase the load ofthe network at least, cause excessive collisions, may end-up looping etc. Consequently the defaultroute should always lead to the ETH interface, unless you are perfectly certain that a packet to non-existing destination IP may never appear (remember you are dealing with complex software writtenand configured by humans).21© RACOM s.r.o. – RipEX Radio modem & RouterRipEX in detail
2.4. Serial SCADA protocolsEven when the SCADA devices are connected via serial port, communication remains secured andaddress-based in all directions (centre-RTU, RTU-centre, RTU-RTU).In router mode, RipEX utilises a unique implementation of various SCADA protocols (Modbus, IEC101,DNP3, Comli, RP570, C24, DF1, Profibus). In this implementation SCADA protocol addresses aremapped to RipEX addresses and individual packets are transmitted as acknowledged unicasts. Polledremote units respond to the unit that contacted them (multi master network possible) using securepackets. When needed, RTU-RTU parallel communication is also possible.2.4.1. Detailed DescriptionEach SCADA protocol, such as Modbus, DNP3, IEC101, DF1, etc., has its own unique message format,and more importantly, its unique way of addressing remote units. The basic task for protocol utility isto check whether a received frame is in the correct protocol format and uncorrupted. Most of the SCADAprotocols use some type of error detection codes (Checksum, CRC, LRC, BCC, etc.) for data integritycontrol, so RipEX calculates this code and check it with the received one.RipEX radio network works in IP environment, so the basic task for the protocol interface utility is toconvert SCADA serial packets to UDP datagrams. Address translation settings are used to define thedestination IP address and UDP port. Then these UDP datagrams are sent to RipEX router, processedand typically forwarded as unicasts over the radio channel to their destination. If the gateway definedin the routing table belongs to the ethernet LAN, UDP datagrams are rather forwarded to the ethernetinterface. After reaching the gateway (typically a RipEX router), the datagram is again forwarded ac-cording to the routing table.Above that, RipEX is can to handle even broadcast packets from serial SCADA protocols. Whenbroadcasts are enabled in the respective Protocol settings, the defined packets are treated as broadcast(e.g. they are not acknowledged on Radio channel). On the Repeater station, it is possible to setwhether broadcast packets shall be repeated or not.Note: UDP datagrams can be acknowledged on the radio channel (ACK parameter of router mode)but they are not acknowledged on the ethernet channel.When a UDP datagram reaches its final IP destination, it should be in a RipEX router again (either itsETH or radio interface). It is processed further according its UDP port. Either it is delivered to COM1(2)port daemon, where the datagram is decapsulated and the data received on serial interface of thesource unit is forwarded to COM1(2), or the UDP port is that of a Terminal server or any other specialprotocol daemon on Ethernet like Modbus TCP etc. Then the datagram is processed by that daemonaccordingly to the respective settings.RipEX uses a unique, sophisticated protocol on the radio channel. It guaranties data integrity evenunder heavy interference or weak signal conditions due to the 32 bit CRC used, minimises the likelihoodof a collision and retransmits frames when collision happens, etc. These features allow for the mostefficient SCADA application arrangements to be used, e.g. multi-master polling and/or spontaneouscommunication from remote units and/or parallel communication between remote units, etc.Note: The anti-collision protocol feature is available only in the router mode. The bridge mode is suitablefor simple Master-Slave arrangements with polling-type application protocol.RipEX Radio modem & Router – © RACOM s.r.o.22RipEX in detail
2.5. Combination of IP and serial communicationRipEX enables combination of IP and serial protocols within a single application.Five independent terminal servers are available in RipEX. A terminal server is a virtual substitute fordevices used as serial-to-TCP(UDP) converters. It encapsulates serial protocol to TCP(UDP) and viceversa eliminating the transfer of TCP overhead over the radio channel.If the data structure of a packet is identical for IP and serial protocols, the terminal server can serve asa converter between TCP(UDP)/IP and serial protocols (RS232, RS485).RipEX also provides a built-in converter Modus RTU – Modus TCP, where data structure is not thesame, so one application may combine both protocols, Modus RTU and Modus TCP.2.5.1. Detailed DescriptionGenerally, a terminal server (also referred to as serial server) enables connection of devices with aserial interface to a RipEX over the local area network (LAN). It is a virtual substitute for the devicesused as serial-to-TCP(UDP) converters.Examples of the use:A SCADA application in the centre should be connected to the radio network via serial interface, however,for some reason that serial interface is not used. The operating system (e.g. Windows) can provide avirtual serial interface to such application and converts the serial data to TCP (UDP) datagrams, whichare then received by the terminal server in RipEX. This type of connection between RipEX and applic-ation provides best results when:• There is no hardware serial interface on the computer• Serial cable between RipEX and computer would be too long. E.g. the RipEX is installed very closeto the antenna to reduce feed line loss.• LAN already exists between the computer and the point of installationNote: The TCP (UDP) session operates only locally between RipEX and the central computer, henceit does not increase the load on the radio channel.In special cases, the terminal server can reduce network load from TCP applications . A TCP sessioncan be terminated locally at the terminal server in RipEX, user data extracted from the TCP messagesand processed as if it came from a COM port. When the data reaches the destination RipEX, it can betransferred to the RTU either via the serial interface or via TCP (UDP), using the terminal server again.Please note, that RipEX Terminal server implementation also supports the dynamical IP port changein every incoming application datagram. In such case the RipEX sends the reply to the port from whichthe last response has been received. This feature allows to extend the number of simultaneouslyopened TCP connections between the RipEX and the locally connected application up to 10 on eachTerminal server.2.6. Diagnostics & network managementRipEX radiomodem offers a wide range of built-in diagnostics and network management tools.23© RACOM s.r.o. – RipEX Radio modem & RouterRipEX in detail
2.6.1. LogsThere are ‘Neighbours’ and Statistic logs in RipEX. For both logs there is a history of 20 log filesavailable, so the total history of saved values is 20 days (assuming the default value of 1440 min. isused as the Log save period).NeighboursThe ‘Neighbours’ log provides information about neighbouring units (RipEX’s which can be accesseddirectly over the radio channel, i.e. without a repeater). Every RipEX on the network regularly broadcastsits status, the set of so called “Watched values”: the probability of packet loss when transmitting dataover the radio channel, current supply voltage, internal temperature, measured RF output power, theVoltage Standing Wave Ratio on the antenna feed line and the total number of packets received from/ transmitted to ETH, COM1, COM2 interfaces. In addition, the RipEX that records this data in its logalso keeps track of how many times it listened to its neighbouring unit as well as of the RSS and DQrecorded. See Adv. Conf., Diagnostic for more.StatisticThe ‘Statistic’ log provides information about the volume of data traffic on all interfaces: radio, ETH,COM1, COM2. It offers detailed information about the number of transmitted packets, their size andthe throughput per second. Moreover, a detailed division into user and service packets is available forthe radio channel. See chapter Adv. Conf., Diagnostic for more.2.6.2. GraphsAn independent database periodically stores the Watched values (see 'Neighbours' log above) fromup to five neighbouring RipEX's and from the local one, there including most important values from theStatistic log. All these values can be displayed as graphs.The graphs are available in summary and detailed versions. Detailed logging is triggered on when athreshold value has been reached for the specific item to enable a more detailed investigation into theunits’ operation when an alarm event occurs. Each graph can display two different elements at once,including their set thresholds. Each of the values may originate from a different RipEX unit.See chapter Adv. Conf., Graphs for more.2.6.3. SNMPRipEX implements an SNMP client ver. 1. The values provided by RipEX are shown in the MIB table.RipEX also allows generating SNMP traps when thresholds have been reached for the monitored values:RSScom, DQcom, TXLost[%], Ucc, Temp, PWR, VSWR, ETH[Rx/Tx], COM1[Rx/Tx], COM2[Rx/Tx],HW Alarm Input.See chapter RipEX App notes, SNMP for RACOM RipEX1for more.2.6.4. PingTo diagnose the individual radio links RipEX is equipped with an enhanced Ping tool. In addition to thestandard info such as the number of sent and received packets or the round trip time, it provides the1http://www.racom.eu/eng/products/m/ripex/app/snmp.htmlRipEX Radio modem & Router – © RACOM s.r.o.24RipEX in detail
overall load, the resulting throughput, BER, PER and specific data about the quality of the radio trans-mission, RSS and DQ for the weakest radio link on the route.See chapter Adv. Conf., Ping for details.2.6.5. MonitoringTMonitoring is an advanced on-line diagnostic tool, which enables a detailed analysis of communicationover any of the interfaces of a RipEX router. In addition to all the physical interfaces (RADIO, ETH,COM1, COM2), some internal interfaces between software modules (e.g. Terminal servers, ModusTCP server etc.) can be monitored when such advanced diagnostics is needed.Monitoring output can be viewed on-line or saved to a file in the RipEX (e.g. a remote RipEX) anddownloaded later.COMPORTSMODULE ROUTER&BRIDGEMODULETERMINAL &MODBUSTCPSERVERSRADIOCHANNELMODULECOM1COM2ETHRADIOvirtualcom ethRipEXRxTxRxTxRxTxRxTxRxTxRxTxRxTxFig. 2.4: MonitoringSee chapter Adv. Conf., Monitoring for details.2.7. Firmware update and upgradeOccasionally RipEX firmware update or upgrade is released. An update improves functionality and/orfix software bugs. Updates can be downloaded for free from www.racom.eu.A firmware upgrade implements significant improvements and new functions which take the productto a new level. Downloading and applying a firmware upgrade is the same as with firmware update.However a software key may have to be purchased and applied to activate the new functionality or theupgrade itself (see the next chapter).See chapter Adv. Conf., Firmware for more.2.8. Software feature keysCertain advanced RipEX features are activated with software keys. Among such code protected featuresare the Router mode, 83 kbps (High speed), COM2, 10 W. This enables the users to initially purchaseonly the functionality they require and buy additional functions as the requirements and expectations25© RACOM s.r.o. – RipEX Radio modem & RouterRipEX in detail
grow. This protects the investment into the hardware. Thanks to SDR-based hardware design of RipEXno physical replacement is necessary – the user simply buys a key and activates the feature.Software keys are always tied to a specific RipEX production code. When purchasing a software key,this production code must be given.See chapter Adv. Conf., SW feature keys for more.RipEX Radio modem & Router – © RACOM s.r.o.26RipEX in detail
3. Network planningThe significance of planning for even a small radio network is often neglected. A typical scenario insuch cases goes as follows – there's not enough time (sometimes money) to do proper planning, sothe network construction is started right away while decisions on antennas etc. are based mainly onbudget restrictions. When the deadline comes, the network is ready but its performance does not meetthe expectations. Finally the (expensive) experts are invited to fix the problem and that fix costs tentimes more than a proper design process done beforehand would have.The following paragraphs are not a guide to network planning – that is a topic far beyond the scope ofa product manual. What is provided is the essential RipEX data needed plus some comments oncommon problems which should be addressed during the planning process.3.1. Data throughput, response timeA UHF radio network provides very limited bandwidth for principal reasons. Hence the first and veryimportant step to be taken is estimating/calculating the capacity of the planned network. The goal is tomeet the application bandwidth and time-related requirements. Often this step determines the layoutof the network, for example when high speed is necessary, only near-LOS (Line-of-sight) radio hopscan be used.RipEX offers an unprecedented range of data rates. The channel width available and signal levels ex-pected/measured on individual hops limit the maximum rate which can be used. The data rate definesthe total capacity of one radio channel in one area of coverage, which is shared by all the radio modemswithin the area. Then several overhead factors, which reduce the total capacity to 25-90% of the "raw"value, have to be considered. They are e.g. RF protocol headers, FEC, channel access proceduresand number of store-and-forward repeaters. There is one positive factor left – an optimum compression(e.g. IP optimization) can increase the capacity by 20-200%.All these factors are heavily influenced by the way the application loads the network. For example, asimple polling-type application results in very long alarm delivery times – an event at a remote is reportedonly when the respective unit is polled. However the total channel capacity available can be 60-95%of the raw value, since there are no collisions. A report-by-exception type of load yields much betterapplication performance, yet the total channel capacity is reduced to 25-35% because of the protocoloverhead needed to avoid and solve collisions.The basic calculations of network throughput and response times for different RipEX settings can bedone at www.racom.eu1.Let us add one comment based on experience. Before committing to the actual network design, it isvery wise to do a thorough bench-test with real application equipment and carefully monitor the loadgenerated. A difference against the datasheets, which may be negligible in a LAN environment, mayhave fundamental consequences for the radio network design. To face that "small" difference whenthe network is about to be commissioned may be a very expensive experience. The bench test layoutshould include the application centre, two remotes (at least) and the use of a repeater. See the followingpicture for an example.1http://www.racom.eu/eng/products/radio-modem-ripex.html#calculation27© RACOM s.r.o. – RipEX Radio modem & RouterNetwork planning
CentreRTUconfig.PCRTUdummyantennaFig. 3.1: Application bench test3.2. FrequencyOften the frequency is simply given. If there is a choice, using the optimum frequency range can makea significant difference. Let us make a brief comparison of the most used UHF frequency bands.160 MHzThe best choice when you have to cover a hilly region and repeaters are not an option. The only fre-quency of the set of options which can possibly make it to a distant valley, 20 km from your nearestpoint-of-presence, it can reach a ship 100 km from the shore base. The penalty you pay is tremendous– high level of noise in urban and industry areas, omnipresent multi-path propagation, vulnerability tonumerous special propagation effects in troposphere etc. Consequently this frequency band is suitablefor low speeds using robust modulation techniques only, and even then a somewhat lower long-termcommunication reliability has to be acceptable for the application.450 MHzThe most popular of UHF frequency bands. It still can get you slightly “beyond the horizon”, while thesignal stability is good enough for 99% (or better) level of reliability. Multi-path propagation can be aproblem, hence high speeds may be limited to near-LOS conditions. Urban and industrial noise doesnot pose a serious threat (normally), but rather the interference caused by other transmissions is quitefrequent source of disturbances.900 MHzThis band requires planning the network in “microwave” style. Hops longer than about 1 km have tohave “almost” clear LOS (Line-of-sight). Of course a 2–5 km link can handle one high building or abunch of trees in the middle, (which would be a fatal problem for e.g. an 11 GHz microwave). 900 MHzalso penetrates buildings quite well, in an industrial environment full of steel and concrete it may bethe best choice. The signal gets “everywhere” thanks to many reflections, unfortunately there is badnews attached to this - the reliability of high speed links in such environment is once again limited.Otherwise, if network capacity is your main problem, then 900 MHz allows you to build the fastest andRipEX Radio modem & Router – © RACOM s.r.o.28Network planning
most reliable links. The price you pay (compared to lower frequency bands) is really the price – morerepeaters and higher towers increase the initial cost. Long term reliable performance is the reward.The three frequency bands discussed illustrate the simple basic rules – the higher the frequency, thecloser to LOS the signal has to travel. That limits the distance over the Earth's surface – there is noother fundamental reason why shorter wavelengths could not be used for long distance communication.On the other hand, the higher the frequency, the more reliable the radio link is. The conclusion is thenvery simple – use the highest frequency band you can.3.3. Signal budgetFor every radio hop which may be used in the network, the signal level at the respective receiver inputhas to be calculated and assessed against requirements. The fundamental requirements are two – thedata rate, which is dictated by total throughput and response times required by the application, and theavailability, which is again derived from the required reliability of the application. The data rate translatesto receiver sensitivity and the availability (e.g. 99,9 % percent of time) results in size of the fade margin.The basic rule of signal budget says, that the difference between the signal level at the receiver inputand the guaranteed receiver sensitivity for the given data rate has to be greater than the fade marginrequired:RX signal [dBm] – RX sensitivity [dBm] >= Fade margin [dB]To calculate the RX signal level, we follow the RF signal path:TXoutputRXinputfeedlinelossfeedlinelosspathlossTXantennagainRXantennagain+ +Fig. 3.2: Signal pathexample:RX signal [dBm] =dBm (TX output 1 W)+30.0+ TX output [dBm]dB (20m cable RG-213 U, 400 MHz)-2.5- TX antenna feeder loss [dB]dBi (half-wave dipole, 0 dBd)+2.1+TX antenna gain [dBi]dB calculated from field measurement)-125.0- Path loss [dB]dB (7-al Yagi antenna, 7.6 dBd)+9.7+ RX antenna gain [dBi]dB (10 m cable RG-58 CU, 400 MHz)-3.1- RX antenna feeder loss [dB]dBm Received Signal Strength (RSS)= -88.8The available TX output power and guaranteed RX sensitivity level for the given data rate have to bedeclared by the radio manufacturer. RipEX values can be found in Table 4.6, “Technical parameters”.29© RACOM s.r.o. – RipEX Radio modem & RouterNetwork planning
Antenna gains and directivity diagrams have to be supplied by the antenna manufacturer. Note thatantenna gains against isotropic radiator (dBi) are used in the calculation. The figures of feeder cableloss per meter should be also known. Note that coaxial cable parameters may change considerablywith time, especially when exposed to an outdoor environment. It is recommended to add a 50-100 %margin for ageing to the calculated feeder loss.3.3.1. Path loss and fade marginThe path loss is the key element in the signal budget. Not only does it form the bulk of the total loss,the time variations of path loss are the reason why a fade margin has to be added. In reality, very oftenthe fade margin is the single technical figure which expresses the trade-off between cost and perform-ance of the network. The decision to incorporate a particular long radio hop in a network, despite thatits fade margin indicates 90 % availability at best, is sometimes dictated by the lack of investment in ahigher tower or another repeater. Note that RipEXs Auto-speed feature allows the use of a lower datarate over specific hops in the network, without the need to reduce the rate and consequently thethroughput in the whole network. Lower data rate means lower (= better) value of receiver sensitivity,hence the fade margin of the respective hop improves. See the respective Application note to learnmore on the Auto-speed feature.When the signal path profile allows for LOS between the TX and RX antennas, the standard formulafor free-space signal loss (below) gives reliable results:Path loss [dB] = 20 * log10 (distance [km]) + 20 * log10 (frequency [MHz]) + 32.5In the real world the path loss is always greater. UHF radio waves can penetrate obstacles (buildings,vegetation), can be reflected from flat objects, can bend over round objects, can disperse behind sharpedges – there are numerous ways how a radio signal can propagate in non-LOS conditions. The addi-tional loss when these propagation modes are involved (mostly combined) is very difficult to calculate.There are sophisticated methods used in RF design software tools which can calculate the path lossand its variations (statistical properties) over a computer model of terrain. Their accuracy is unfortunatelyvery limited. The more obstacles on the path, the less reliable is the result. Such a tool can be veryuseful in the initial phase of network planning, e.g. to do the first network layout for the estimate of totalthroughput, however field measurements of every non-LOS radio hop should be done before the finalnetwork layout is designed.Determining the fade margin value is even more difficult. Nevertheless the software tools mentionedcan give some guidance, since they can calculate the statistical properties of the signal. Generally thefade margin (for given availability) is proportional to the difference between the real path loss and theLOS path loss over the same distance. Then it is about inversely proportional to frequency (in the UHFrange at least). To give an example for 10 km, non-LOS, hop on 450 MHz, fade margin of 20 dB is abare minimum. A field test may help again, provided it is run for longer period of time (hours-days).RipEX diagnostic tools (ping) report the mean deviation of the RSS, which is a good indication of thesignal stability. A multiple of the mean deviation should be added to the fade margin.3.4. Multipath propagation, DQMultipath propagation is the arch-enemy of UHF data networks. The signal coming out of the receivingantenna is always a combination of multiple signals. The transmitted signal arrives via different paths,by the various non-LOS ways of propagation. Different paths have different lengths, hence the waveformsare in different phases when hitting the receiving antenna. They may add-up, they may cancel eachother out.RipEX Radio modem & Router – © RACOM s.r.o.30Network planning
TXantennaFig. 3.3: Multipath propagationWhat makes things worse is that the path length changes over time. Since half the wavelength – e.g.0.3 m at 450 MHz - makes all the difference between summation and cancellation, a 0.001% changeof a path length (10 cm per 10 km) is often significant. And a small change of air temperature gradientcan do that. Well, that is why we have to have a proper fade margin. Now, what makes things reallybad is that the path length depends also on frequency. Normally this dependency is negligible withinthe narrow channel. Unfortunately, because of the phase combinations of multiple waveforms, theresulting signal may get so distorted, that even the sophisticated demodulating techniques cannot readthe original data. That is the situation known to RF data network engineers – signal is strong enoughand yet “it” does not work.That is why RipEX reports the, somewhat mystic, figure of DQ (Data Quality) alongside the RSS. Thesoftware demodulator uses its own metrics to assess the level of distortion of the incoming signal andproduces a single number in one-byte range (0–255), which is proportionate to the “quality” of the signal.Though it is very useful information, it has some limitations. First, it is almost impossible to determinesignal quality from a single packet, especially a very short one. That results in quite a jitter of DQ valueswhen watching individual packets. However when DQ keeps jumping up and down it indicates a seriousmultipath problem. In fact, when DQ stays low all the time, it must be noise or permanent interferencebehind the problem. The second issue arises from the wide variety of modulation and data rates RipEXsupports. Though every attempt has been made to keep the DQ values modulation independent, thedifferences are inevitable. In other words, experience is necessary to make any conclusions from DQreading. The less experience you have, the more data you have to collect on the examined link anduse other links for comparison.The DQ value is about proportional to BER (bit error ratio) and about independent of the data rate andmodulation used. Hence some rule-of-thumb values can be given. Values below 100 mean the link isunusable. At 125 short packets should get through with some retransmissions, 150 and above can beconsidered “good” values.3.4.1. How to battle with multipath propagation?The first step is the diagnosis. We have to realize we are in trouble and only a field measurement cantell us that. We should forget about software tools and simply assume that a multipath problem mayappear on every non-LOS hop in the network.These are clear indicators of a serious multipath propagation problem:• directional antennas "do not work", e.g. a dipole placed at the right spot yields a better RSS thana long Yagi, or rotating the directional antenna shows several peaks and troughs of the signal andno clear maximum• RSS changes rapidly (say 10 dB) when antenna is moved by less than a meter in any direction31© RACOM s.r.o. – RipEX Radio modem & RouterNetwork planning
• ping test displays the mean deviation of RSS greater than 6 dB• DQ value keeps "jumping" abnormally from frame to frameQuite often all the symptoms mentioned can be observed at a site simultaneously. The typical "beginner"mistake would be to chase the spot with the best RSS with an omnidirectional antenna and installingit there. Such a spot may work for several minutes (good luck), sometimes for several weeks (bad luck,since the network may be in full use by then). In fact, installing in such a spot guaranties that troublewill come - the peak is created by two or more signals added up, which means they will cancel outsooner or later.The right strategy is to find an arrangement where a single signal becomes dominant, possibly themost stable one. "Sweeping" a directional antenna around the place (in different heights and with dif-ferent polarization) can tell us where the signals come from. If individual signals come from differentdirections, there is a good chance a long yagi can solve the problem by selecting just one of the bunch.Finding a spot where the unwanted signal is blocked by a local obstacle may help as well (e.g. installingat a side of the building instead of at the roof).TXantennabettermultipathFig. 3.4: Antenna locationWhen the multiple signals come from about the same direction, a long yagi alone would not help much.We have to move away from the location, again looking for a place where just one of the signals becomesdominant. 20–50 metres may save the situation, changing the height (if possible) is often the rightsolution. Sometimes changing the height means going down, not up, e.g. to the base of the buildingor tower.We have to remember our hop has two ends, i.e. the solution may be to change antenna or its placementat the opposite end. If everything fails, it is better to use another site as a repeater. Even if such prob-lematic site seems to be usable after all (e.g. it can pass commissioning tests), it will keep generatingproblems for ever, hence it is very prudent to do something about it as early as possible.Note: Never design hops where a directional antenna is used for a direction outside its main lobe.However economical and straightforward it may seem, it is a dangerous trap. Enigmatic cases of drop-outs lasting couple of minutes every other day, over a clear LOS hops were created exactly like that.They look like interference which is very difficult to identify and , alas, they are caused by pure multipathpropagation, a self-made one. So always use a combiner and another directional antenna if such ar-rangement is needed. Always.RipEX Radio modem & Router – © RACOM s.r.o.32Network planning
combinercorrectlyincorrectlyFig. 3.5: Main lobe3.5. Network layoutCertainly the network layout is mostly (sometimes completely) defined by the application. When theterrain allows for direct radio communication among all sites in the network, the designer can do neithertoo good nor too bad a job. Fortunately for RF network designers, the real world is seldom that simple.The conditions every single radio hop has to meet were discussed in previous paragraphs. If we areso lucky, that different layouts meeting that conditions are possible, we should exploit that for the be-nefit of the network. The following rules should be followed when defining the layout of radio hops:• dominant radio sites (e.g. telco towers on hill tops) should be avoided whenever possible. Placinga single repeater which serves most part of the network from the top of a hill is a straightforwardbut worst alternative, which makes the whole network very vulnerable. First, a dominant site is ex-posed to interference from a large area; second, such site is typically crowded with radio equipmentof all kinds, which keeps being added, moved (also failing to work properly), so local interferencemay appear anytime; third, it makes the majority of communication paths dependent on a singlesite, so one isolated failure may stop almost the entire network.• when total throughput is important, typically in report-by-exception networks, splitting the networkinto several independent or only slightly overlapping areas of coverage can help. The placement33© RACOM s.r.o. – RipEX Radio modem & RouterNetwork planning
of repeaters which serve the respective areas is crucial. They should be isolated from each otherwhenever possible.MRepeaterCentreincorrectlyFig. 3.6: Dominant repeaterMCentreFig. 3.7: Isolated branches• in report-by-exception networks the load of hops connecting the centre to major repeaters formsthe bottle-neck of total network capacity. Moving these hops to another channel, or, even better, toa wire (fibre, microwave) links can multiply the throughput of the network. It saves not only the loaditself, it also significantly reduces the probability of collision. More on that in the following chapter3.6..RipEX Radio modem & Router – © RACOM s.r.o.34Network planning
3.6. Hybrid networksIf an extensive area needs to be covered and multiple retranslation would be uneconomical or unsuitable,RipEX’s can be interconnected via any IP network (WLAN, Internet, 3G, etc.). This is quite simple be-cause RipEX is a standard IP router with an ethernet interface. Consequently interconnecting two ormore RipEX's over a nested IP network is a standard routing issue and the concrete solution dependson that network.3.7. Assorted practical commentsLet us mention few issues, whose influence on network reliability or performance is sometimes neglectedby less experienced planners:• Both vegetation and construction can grow. Especially when planning a high data rate hop whichrequires a near-LOS terrain profile, take into consideration the possible future growth of obstacles.• When the signal passes a considerable amount of vegetation (e.g. a 100m strip of forest), think ofthe season. Typically the path loss imposed by vegetation increases when the foliage gets denseor wet (late spring, rainy season). Hence the fade margin should be increased if your field measure-ments are done in a dry autumn month. The attenuation depends on the distance the signal mustpenetrate through the forest, and it increases with frequency. According to a CCIR, the attenuationis of the order of 0.05 dB/m at 200 MHz, 0.1 dB/m at 500 MHz, 0.2 dB/m at 1 GHz. At lower frequen-cies, the attenuation is somewhat lower for horizontal polarization than for vertical, but the differencedisappears above about 1 GHz.• Though being a rare problem, moving metallic objects may cause serious disruptions, especiallywhen they are close to one end of the radio hop. They may be cars on a highway, blades of a windturbine, planes taking off from a nearby airport runway etc.• Even when the signal is very strong, be careful when considering various cheap whips or moregenerally any antennas requiring a ground plane to function properly. A tempting scenario is to usethe body of the metallic box, where the radio modem and connected application equipment (oftena computer) is installed, as the ground plane, which leads to never-ending problems with locallygenerated noise. The ground plane forms an integral part of such an antenna, hence it has to bein a safe distance (several metres) from any electronic equipment as well as the antenna itself. Ametallic plate used as shielding against interference must not form a part of the antenna.35© RACOM s.r.o. – RipEX Radio modem & RouterNetwork planning
incorectly correctlyPowersupplyRTUFig. 3.8: Antenna mounting• Do not underestimate ageing of coaxial cables, especially at higher frequencies. Designing a 900MHz site with 30 m long antenna cable run outdoors would certainly result in trouble two years later.• We recommend to use vertical polarization for all radio modem networks.RipEX Radio modem & Router – © RACOM s.r.o.36Network planning
4. ProductRipEX is built into a rugged die-cast aluminium casing that allows for multiple installation possibilities,see Section 6.1, “Mounting”.4.1. DimensionsDIN35RailDINRailClip134150 1185850Fig. 4.1: RipEX dimensions, see more1339512460122122175L -bracket Flat-bracket8702×o4,5 4×M3/Fig. 4.2: L-bracket and Flat-bracket, see more37© RACOM s.r.o. – RipEX Radio modem & RouterProduct
4.2. ConnectorsAll connectors are located on the front panel. The upper side features an LED panel. The RESET buttonis located in an opening in the bottom side.ALARMOUT.ALARMINPUT+ –SLEEP -WAKEUPCOM1COM2dataequipment,RTUETHdataequipment,RTULAN,controlPCETH/USB ADAPTERANTENNA10–30VDC++ETHFig. 4.3: Connectors4.2.1. AntennaFig. 4.4: Antenna connector TNCAn antenna can connect to RipEX via TNC female 50Ω connector.A model with two antenna connectors can be supplied to order,in which the Rx and Tx antennas are separate. See chapterSection 4.5, “Model offerings”.RipEX Radio modem & Router – © RACOM s.r.o.38Product
Fig. 4.5: Separated Rx and TX antennasWarning: RipEX radio modem may be damaged when operated without an antenna or a dummy load.4.2.2. Power and ControlThis rugged connector connects to a power supply and it contains control signals. A Plug with screw-terminals and retaining screws for power and control connector is supplied with each RipEX. It is Tyco7 pin terminal block plug, part No. 1776192-7, contact pitch 3.81 mm. The connector is designed forelectric wires with a cross section of 0.5 to 1.5 mm2. Strip the wire leads to 6 mm (1/4 inch). Isolatedcables should receive PKC 108 or less end sleeves before they are inserted in the clip. Insert the cablesin the wire ports, tightening securely.Tab. 4.1: Pin assignementsignallabeledpinSLEEP INSI1ALARM INAI2−(GND) – for SLEEP IN, ALARM IN−3+(PWR) – for ALARM OUT+4ALARM OUTAO5+PWR (10 to 30 V)+10–30VDC6−PWR (GND)−10–30VDC7Pins 3 and 7, 4 and 6 are connected internally.39© RACOM s.r.o. – RipEX Radio modem & RouterProduct
1 2 3 4 5 6PinNo.: 7SI AI - + A0 +-10–30VDCFig. 4.6: Supply connectorWirePorts(7)RetainingScrews(2)LeadBindingScrews(7)Fig. 4.7: Power and Control - cable plug1 2 3 4 5 6PinNo.: 7SI AI - + A0 +-10–30VDCSleepInputSLEEP INSLEEP IN is the digital input for activating the Sleep mode. Whenthis pin is grounded (for example when connected to pin 3), theRipEX switches into the Sleep mode. Using Power management(Advanced Config.), the Entering the Sleep mode can be delayedby a set time. Disconnecting SLEEP IN from GND (-) ends theSleep mode. Note that RipEX takes 25 seconds to wake up fromthe Sleep mode.1 2 3 4 5 6PinNo.: 7SI AI - + A0 +-10–30VDCAlarmInputALARM INALARM IN is a digital input. If grounded (e.g. by connecting toPIN 3), an external alarm is triggered. This alarm can be usedfor example to transmit information using SNMP trap, informingfor instance about a power outage or RTU problem. For detailsabout Alarm management see chapter Advanced Configuration.1 2 3 4 5 6PinNo.: 7SI AI - + A0 +-10–30VDCAlarmOutputmax.30VDC,1 AALARM OUTALARM OUT is a digital output. It can be activated in Alarmmanagement settings, chapter Advanced Configuration. It maybe used for instance to switch on the Fan kit if the preset maxim-um internal temperature is exceeded or to inform the connectedRTU about a RipEX alarm. If an alarm is triggered, ALARM OUTis internally connected to GND. If the external device requiresconnection to positive terminal of the power supply, PIN 4 shouldbe used.PWRThe PWR pins labelled + and - serve to connect a power supply 10–30 VDC. The requirements for apower supply are defined in Section 6.6, “Power supply” and Section 4.4, “Technical specification”.RipEX Radio modem & Router – © RACOM s.r.o.40Product
4.2.3. ETHStandard RJ45 connector for ethernet connection. RipEX has 10/100 BaseT Auto MDI/MDIX interfaceso it can connect to 10 Mbps or 100 Mbps ethernet network. The speed can be selected manually orrecognised automatically by RipEX. RipEX is provided with Auto MDI/MDIX function which allows it toconnect over both standard and cross cables, adapting itself automatically.Pin assignementFig. 4.8: RJ-45FTab. 4.2: Ethernet to cable connector connectionsCrossed cableDirect cableSignalPINgreen – whiteorange – whiteTX+1greenorangeTX−2orange – whitegreen – whiteRX+3blueblue—4blue – whiteblue – white—5orangegreenRx−6brown – whitebrown – white—7brownbrown—84.2.4. COM1 and COM2RipEX provides two serial interfaces COM1 and COM2 terminated by DSUB9F connectors. COM1 isalways RS232, COM2 can be configured as RS232 or RS485 (more in Adv. Conf., COM's).RipEX‘s RS232 is a hard-wired DCE (Data Communication Equipment) device. Equipment connectedto the RipEX’s serial ports should be DTE (Data Terminal Equipment) and a straight-through cableshould be used. If a DCE device is connected to the RipEX‘s serial ports, a null modem adapter orcross cable has to be used.Fig. 4.9: Serial connectorTab. 4.3: COM1,2 pin descriptionCOM2 – RS485COM1, 2 – RS232DSUB9FIn/ OutsignalIn/ Outsignalpin—OCD1I/Oline BORxD2I/Oline AITxD3—IDTR4GNDGND5—ODSR6—IRTS7—OCTS8———9RipEX keeps pin 6 DSR at the level of 1 by RS232 standard permanently.41© RACOM s.r.o. – RipEX Radio modem & RouterProduct
4.2.5. USBRipEX uses USB 1.1, Host A interface. USB interface is wired as standard:1 2 3 4Fig. 4.10: Serial connectorTab. 4.4: USB pin descriptionwiresignalUSB pinred+5 V1whiteData(−)2greenData (+)3blackGND4The USB interface is designed for the connection to the "X5" – external ETH/USB adapter. The "X5"is an optional accessory to RipEX, for more see Section 5.3, “Connecting RipEX to a programmingPC”. The adapter is used for service access to RipEX’s web configuration interface.The USB connector also provides power supply (5 V/ 0.5 A). It can be used to temporarily power aconnected device, for instance a telephone. The USB connector should not be used as permanentsource of power supply.4.2.6. Reset buttonFig. 4.11: ResetRipEX’s bottom-side enclosure includes a reset button accessible throughan opening. When this button is pressed, the STATUS diode on the LEDpanel goes dark (indicating that the button has been pressed). If you holdthe button for 5 seconds, the STATUS diode starts flashing slowly indicat-ing that the reset is complete. If you continue to hold the button for 15 ormore seconds (the STATUS diode starts flashing quickly) and then releaseit, you will reset the device’s access information to default: parameterssuch as the login, password and ethernet IP will be reset to their defaults.Resetting access parameters to defaults also sets the Ethernet speed to„Auto“ and results in clearing all firewall rules (which may have beenblocking the access by accident). Remember to re-install your firewall if you are using one.NoteTo reset the RipEX only use the RESET button as described above or use the button in RipEX’s webconfiguration, see Adv. Conf., Maintenance. Never use a power cycling (disconnecting and reconnectingpower supply) to reset it. While power cycle resets, or rather reboots the RipEX, its software will notterminate correctly resulting in logs, statistics and graphs not being saved properly.4.2.7. GPSFig. 4.12: GPS Connector SMARipEX can be equipped with an internal GPS, see Section 4.5,“Model offerings”. The GPS module is used for time synchronisationof the NTP server inside RipEX. See Adv. Conf., Time for more. Inthis case the front panel contains a SMA female 50 ohm connectorfor connecting the GPS antenna.RipEX Radio modem & Router – © RACOM s.r.o.42Product
4.3. Indication LEDsFig. 4.13: Indication LEDsTab. 4.5: Key to LEDsDescriptionColorThe RipEX OS (Linux) is runningsuccesfulyGreenSTATUSReset button has been pressedDarkreset after five-seconds pressingthe Reset buttonGreen flashes slowlydefault access after 15-secondspressing the Reset buttonGreen flashes quicklyStatus alarmRedtransmitting to radio channelRedTXreceiver is synchronised to apacketGreenRX there is a signal stronger than−80 dBm on Radio channelYellowdata receivingGreenCOM2 data transmittingYellowdata receivingGreenCOM1 data transmittingYellow100 Mb/s speedYellow ONETH 10 Mb/s speedYellow OFFconnectedGreen ONethernet dataGreen flashespowered succesfulyGreenPWR Save modeBlinks with a period of 1 secSleep modeFlashes once per 3 sec43© RACOM s.r.o. – RipEX Radio modem & RouterProduct

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