. RipEX Application notes . version 1.2 1/31/2012 fw 1.0.9.0 RACOM s.r.o. • Mirova 1283 • 592 31 Nove Mesto na Morave • Czech Republic Tel.: +420 565 659 511 • Fax: +420 565 659 512 • E-mail: racom@racom.eu www.racom.
Table of Contents 1. Address planing ............................................................................................................................... 5 1.1. End devices connected via serial interface .......................................................................... 5 1.2. End devices connected over Ethernet .................................................................................. 8 1.3. Ethernet addressing .....................................................................
Address planing 1. Address planing In Router mode standard IP routing is used between individual RipEX radio modems and their interfaces. The only non-standard feature is that even if you assign all RipEX's radio interface IP addresses to a single network, the RipEX's may not "hear" each other over the radio channel; therefore, routing tables should include even routes within the same network (over repeaters).
Address planing 10.10.10.18 via 10.10.10.16 10.10.10.19 via 10.10.10.16 • For 10.10.10.16 10.10.10.18 via 10.10.10.17 10.10.10.19 via 10.10.10.17 • For 10.10.10.17 10.10.10.15 via 10.10.10.16 • For 10.10.10.18 10.10.10.15 via 10.10.10.17 10.10.10.16 via 10.10.10.17 10.10.10.19 via 10.10.10.17 (this record is only necessary if you require communication between end devices 19 and 18) • For 10.10.10.19 10.10.10.15 via 10.10.10.17 10.10.10.16 via 10.10.10.17 10.10.10.18 via 10.10.10.
Address planing If SCADA device addresses can be chosen arbitrarily, routing can be significantly simplified when radio IP addresses can be grouped to subnets according to radio network layout. One example of simplification is shown with repeaters connecting to separate subnets. The routing table can then contain a single record for all devices on the subnet. In this example the first repeater connects to subnet 10.10.10.0/29, i.e. devices may have addresses from 10.10.10.1 to 10.10.10.6 (10.10.10.
Address planing Destination via Gateway 10.10.10.1/29 via 10.10.10.2 10.10.10.8/29 via 10.10.10.9 10.10.10.16/29 via 10.10.10.17 • For 10.10.10.2 10.10.10.8/29 via 10.10.10.9 10.10.10.16/29 via 10.10.10.17 • For 10.10.10.3 and 10.10.10.4 and 10.10.10.5 10.10.10.248/29 via 10.10.10.2 10.10.10.8/29 via 10.10.10.2 10.10.10.16/29 via 10.10.10.2 • For 10.10.10.9 10.10.10.1/29 via 10.10.10.2 10.10.10.8/29 via 10.10.10.9 • For 10.10.10.10 and 10.10.10.11 and 10.10.10.12 10.10.10.248/29 via 10.10.10.9 10.10.
Address planing B. C. There are no limitations to setting up routing in this case. The only rule is that the range of radio and Ethernet IP addresses must not overlap. If you can only set the IP address, network mask and gateway, not the routing table in the IP device connected to RipEX In this case destination addresses must not be on the same network (i.e. the destination address must always be outside of the network mask).
Address planing T: 192.168.255.0/24 via 10.10.1.5 T: 192.168.1.0/26 via 10.10.1.5 192.168.255.0/24 via 10.10.1.1 *192.168.2.0/24 via 10.10.1.1 *192.168.3.0/24 via 10.10.1.1 10.10.1.9/24 192.168.1.6/24 T: 192.168.1.0/29 via 10.10.1.9 192.168.1.8/29 via 10.10.1.10 192.168.255.0/24 via 10.10.1.2 Eth 10.10.1.5/24 192.168.1.62/24 10.10.1.2/24 192.168.1.254/24 S 10.10.1.10/24 192.168.1.14/24 Eth S 192.168.1.61/24 gw:192.168.1.62 Eth Eth S 192.168.1.253/24 gw:192.168.1.254 S 10.10.1.6/24 192.168.2.
Address planing T: 192.168.255.0/24 via 10.10.1.5 T: 192.168.1.0/26 via 10.10.1.5 192.168.255.0/24 via 10.10.1.1 *192.168.2.0/24 via 10.10.1.1 *192.168.3.0/24 via 10.10.1.1 10.10.1.9/24 192.168.1.6/29 T: 192.168.1.0/29 via 10.10.1.9 192.168.1.8/29 via 10.10.1.10 192.168.255.0/24 via 10.10.1.2 Eth 10.10.1.5/24 192.168.1.62/29 10.10.1.2/24 192.168.1.254/26 S 10.10.1.10/24 192.168.1.14/29 Eth S 192.168.1.61/29 gw:192.168.1.62 Eth Eth S 192.168.1.253/26 gw:192.168.1.254 S 10.10.1.6/24 192.168.2.
SNMP for RACOM RipEX 2. SNMP for RACOM RipEX 2.1. Simple Network Management Protocol SNMP is a simple, widespread and useful standardised protocol used to read values from devices or to set them. Values can be obtained at regular intervals, saved to a database and then displayed as a graph. It allows you to, for instance, monitor activity on the radio channel, temperature history or data flow through ports. SNMP also enables you to generate and receive alarms (SNMP traps). 2.1.1.
SNMP for RACOM RipEX 2.1.3. MIB database – Management Information Base OID, which uniquely identifies every value in SNMP, is formed by a sequence of numbers divided by points. This number is derived from superordinate element's OID, divided by a full stop from the current number. The entire tree structure is saved to MIB database. In addition, MIB database contains the names and descriptions of individual values (OID).
SNMP for RACOM RipEX 2.2.1.
SNMP for RACOM RipEX stRemBytesTX stRemDuplicates stRemRepeats stRemLost stRemCtlPacketsRX stRemCtlPacketsTX stRemDataErr stRemRejected stRemTotalPacketsRX stRemTotalPacketsTX stRemTotalBytesRX stRemTotalBytesTX stCom stComNumber stComTable stComEntry stComIndex stComPacketsRX stComPacketsTX stComBytesRX stComBytesTX watchedValues wvLocal wvNoiseLast wvNoiseAvg wvLoadLast wvLoadAvg wvTxlostLast wvTxlostAvg wvUccLast wvUccAvg wvTempLast wvTempAvg wvRfpwrLast wvRfpwrAvg wvVswrLast wvVswrAvg wvRemoteNumber wv
SNMP for RACOM RipEX RipEX SNMP Traps SNMP Traps ripextraps trpRss trpDq trpNoise trpLoad trpTxlost trpUcc trpTemp trpRfpwr trpVswr trpLanPr trpCom1Pr trpCom2Pr trpHwIn 1.3.6.1.4.1.33555.2.10 1.3.6.1.4.1.33555.2.10.1 1.3.6.1.4.1.33555.2.10.2 1.3.6.1.4.1.33555.2.10.3 1.3.6.1.4.1.33555.2.10.4 1.3.6.1.4.1.33555.2.10.5 1.3.6.1.4.1.33555.2.10.6 1.3.6.1.4.1.33555.2.10.7 1.3.6.1.4.1.33555.2.10.8 1.3.6.1.4.1.33555.2.10.9 1.3.6.1.4.1.33555.2.10.10 1.3.6.1.4.1.33555.2.10.11 1.3.6.1.4.1.33555.2.10.12 1.3.6.1.4.1.
SNMP for RACOM RipEX 2.2.4. Example of Zenoss settings for RipEX These examples merely illustrate certain Zenoss settings. Refer to Zenoss manual for more information. If you want to view MIB in Zenoss, go to Advanced – MIBs. Fig. 2.2: RipEX MIB in Zenoss To set global parameters of SNMP Managers in Zenoss select the Edit config command under Advanced – Settings – Daemons – zenperfsnmp. © RACOM s.r.o.
SNMP for RACOM RipEX Fig. 2.3: Setting SNMP Manager parameters in Zenoss Other parameters, such as SNMP Performance Cycle Interval (secs) use the Edit command in Advanced – Collectors – localhost. Fig. 2.4: Setting SNMP Cycle Interval in Zenoss In this example, a RipEX template was created in Zenoss using Advanced – Monitoring Templates with individual OIDs from RipEX MIB. 18 RipEX Application notes – © RACOM s.r.o.
SNMP for RACOM RipEX Fig. 2.5: Template for RipEX in Zenoss The individual OIDs can be grouped in graphs which depict the changes of monitored values over time. Thresholds can be defined for these values along with type (info, warning, error, etc.) as well as Event Class, etc. Fig. 2.
SNMP for RACOM RipEX Fig. 2.7: Displaying graphs for a specific device in Zenoss Zenoss also allows you to display current, average and maximum values in graphs. 20 RipEX Application notes – © RACOM s.r.o.
Data speed and Modulations 3. Data speed and Modulations On efficient use of narrowband radio channel Introduction The industrial narrowband land mobile radio (LMR) devices, as considered in this paper, have been the subject to European standard ETSI EN 300 113 [1]. The system operates on frequencies between 30 MHz and 1 GHz, with channel separations of up to 25 kHz, and is intended for private, fixed, or mobile, radio packet switching networks.
Data speed and Modulations to the extreme adjacent channel transmitted power (ACP) attenuation requirements, and inherent robustness against channel nonlinearities. Relatively simple implementation of non-coherent demodulators and synchronization algorithms also significantly contributes to the efficient channel usage, especially in packet-based switching networks. The systems thus maintain good power efficiency while the spectral efficiency reaches compromising values not exceeding 1 bit/s/Hz. 3.1.1.
Data speed and Modulations In the systems, where the transmitter power efficiency is of high importance, the transmitter nonlinearity also creates an important issue. Generally speaking, the higher the transmitter nonlinearity, the higher the transmitter efficiency can be reached. Unfortunately, the device with a nonlinear transfer function also tends to distort the spectrum of the transmitted signal, especially if the modulated signal exhibits the non-constant modulation envelope.
Data speed and Modulations Fig. 3.3: Modulated signal spectrums. (left) π/4-DQPSK with R=17.3 kBaud, (right) 16-DEQAM with R=17.3 kBaud. As for the linear modulation techniques, the differentially encoded formats π/4-DQPSK, D8PSK and 16-DEQAM have been selected and tested mainly due to their low modulation envelope variations and inherent robustness against negative effects of signal propagation through the narrowband radio channel.
Data speed and Modulations Tab. 3.1: Measurement results of the transmitter parameters for selected modes of operation. Modulation Symbol Modul. Format Rate Parameter [-] Pout ACI Lower Upper Occupied Bandwidth @ 99.9% PIN ηTX Spectrum plot [kBaud] [-] [dBm] [dBc] [dBc] [kHz] [W] [%] [-] 10.4 h=0.6, α=0.28 40 -62 -61 19.8 35 29 Fig. 3.1 17.3 h=0.2, α=0.28 40 -62 -61 16.6 35 29 Fig. 3.1 10.4 h=0.3, α=0.28 40 -61 -60 19.6 35 29 Fig. 3.2 17.3 h=0.1, α=0.
Data speed and Modulations Assigning this value as S, one can also express what signal-to-noise ratio (SNR) can be expected in relation to noise figure (NF) and transformed to the receiver input SNR = S -(10.log(kT)+10.log(BN)+NF) [dB]. (2.1) In (2.1), k is the Boltzmann’s constant, T is the absolute temperature in Kelvin and BN is the receiver noise bandwidth of e.g. 25 kHz. 3.2.1. Maximum usable data sensitivity In this section, the results of maximum usable data sensitivity measurement (Figure 3.
Data speed and Modulations Fig. 3.5: Maximum usable sensitivity measurement results. Channel separation 25 kHz. 3.2.2. Efficient use of narrowband radio channel As it has been written in the Section 1, the radio transceiver in exponential modulation mode can make use of higher transmitter power. In order to take this fact into account the system gain (SG) or the maximum allowed path loss (2.2) SG [dB] = Pout- S , (2.2) is usually calculated for the wireless communication systems.
Data speed and Modulations Tab. 3.2: Overall performance characteristics of the narrowband radio transceiver for selected modes of operation. Data Spectrum Sensitivity -2 Efficiency @ BER 10 Available Output Power System Gain [dBm] [dBm] [dB] 0.42 -117 40 157 17.36 0.69 -107 40 147 10.42 20.83 0.83 -113 40 153 h=0.1, α=0.28 17.36 34.72 1.39 -102 40 142 π/4-DQPSK α=0.4 17.36 34.72 1.39 -112 35 147 D8PSK α=0.4 17.36 52.08 2.08 -107 35 142 16-DEQAM α=0.4 17.36 69.
Data speed and Modulations • For applications where higher data throughputs are needed the additional increase in spectrum efficiency can be gained by D8PSK and 16-DEQAM modulation formats. However, compared to π/4DQPSK, an increase in overall communication efficiency cannot be expected, while there is the inevitable penalty in power efficiency characteristic. References [1] ETSI EN 300 113-1 V1.6.
Autospeed 4. Autospeed Normally all radio modems in a network have to transmit with the same data rate on the same radio channel. The Autospeed feature of RipEX enables different speeds to be used simultaneously in a radio modem network. The following picture gives an example of a network layout. Let us assume, that all signals are strong enough to ensure almost perfect operation: Fig. 4.
Autospeed to four times) of the whole network, quite probably making it unusable for the application. RipEX Autospeed feature allows to change the transmission data rate at the affected radios only, the rest of the network may continue in full speed. Consequently the overall performance of network is maintained practically at the same level while no additional investment is required. More over, the whole fix can be done in minutes from behind a web-browser screen while sitting in your office.
Back-to-Back repeater 5. Back-to-Back repeater This layout and settings may be used if you need to operate different parts of the radio network on different frequencies. Connection between these two parts is realised by Back2Back connection between two RipEX's (hereafter referred to as border RipEX's), each of which operates on different frequency. 5.1. Back to Back in Bridge mode Ethernet If end devices are connected to RipEX's over Ethernet, border RipEX's can be connected with an Ethernet cable.
Back-to-Back repeater f2 f1 Eth IP: 192.168.10.1 Eth IP: 192.168.10.3 Eth IP: 192.168.10.253 Back2Back S S Eth IP: 192.168.10.100 Mask: 255.255.255.0 Eth IP: 192.168.10.300 Mask: 255.255.255.0 f2 f1 Eth cable Eth IP: 192.168.10.4 Eth IP: 192.168.10.2 Eth IP: 192.168.10.254 S S Eth IP: 192.168.10.200 Mask: 255.255.255.0 Eth IP: 192.168.10.400 Mask: 255.255.255.0 Fig. 5.2: Back2Back in bridge mode Eth IP: 192.168.20.254 Radio IP: 10.32.10.20 Routing 192.168.30.00/24 via 10.32.10.
Combining MORSE and RipEX networks 6. Combining MORSE and RipEX networks When expanding a MORSE network with RipEX radio modems, different arrangements are possible. In the following paragraphs we assume that the whole network is divided into two parts – the MORSE part and the RipEX part. The two parts are interconnected through two radio modems – one MRxxx and one RipEX, hereafter referred to as border radio modems.
Combining MORSE and RipEX networks If the Master is located on the side of the MRxxx, the border MRxxx should be set to Slave. Depending on the SCC interface used the MRxxx should use Multiaddressing with addresses of all the Slave units on the RipEX network.
Combining MORSE and RipEX networks 6.2.2. Terminal devices connected to COM A MORSE network can only be expanded with RipEX modems if the application protocol is supported both by MORSE and RipEX, or if RipEX's UNI protocol can be used instead. If you want to use protocols which are not implemented in RipEX by default, please consult RACOM's technical support. The COM port of the border RipEX and the RS232 of the border MRxxx are connected with crosslink serial cable, see Fig. 6.
Profibus 7. Profibus Radio modem RipEX supports the most widely spread Profibus (Process Field Bus) type designated Profibus DP (Decentralized Periphery) type 0 (see http://www.profibus.com/technology/profibus/). Profibus DP is designed for fast master–slave communication. The central master unit communicates with the remote slaves using RS485 bus. They are typically connected by twisted pair cabling.
Profibus 7.2. Profibus settings We will only be looking at the basic communication parameters of the protocol – other parameters correspond to the standard Profibus DPV0. Profibus protocol is very sensitive to DP Slave response times. Delays are common in radio networks; this should be taken into account when setting up Profibus communication parameters. Recommended default Profibus settings for data transfer using RipEX radio modems: Tslot_Init: 16 383 t_bit Max. Tsdr: 50 t_bit Min.
Profibus DP slave properties window opens. Click on the PROFIBUS button: Properties – PROFIBUS window opens. Select the Transmission Rate (19.2 Kbps or 9.6 Kbps) under the Network Settings tab. The recommended value is 19.2 Kbps. Under Profile select User Defined and click Bus Parameters. © RACOM s.r.o.
Profibus PROFIBUS_DP is the most important settings window; fill in settings as shown below, click Recalculate and confirm by clicking OK. Confirm the values in all open windows and click the icon Download to Module. Tslot_Init is a value which fundamentally influences operation of the entire device. 16 383 t_bit is the maximum value which helps test radio transmission. We recommend setting as described in chapter "Advanced Settings – Calculation of minimum slot time". 7.3. RipEX settings 7.3.1.
Profibus Router mode should only be used where network topology does not allow for Bridge mode to be used (see page YY of the manual). If you choose to use Router mode we recommend switching off acknowledgement on the radio channel. This speeds up packet transmission on the radio channel. Repetition of undelivered packets is ensured through the application layer of the DP Master. 7.3.2. COM 2 Fig. 7.2: ACK Off Profibus DP utilises RS485 interface. This interface can only be set to COM2 in RipEX.
Profibus 7.4.2. Router mode - timing Router mode web based settings may cause time problems in more complex networks. CLI lets you adjust radio channel access parameters and set up repetition taking into account the number of retranslations in your radio network. If you only use the Profibus protocol with RipEX and no other broadcast interferes with your network, you can configure certain parameters to shorten the access time to channel using CLI.
Modbus TCP/RTU 8. Modbus TCP/RTU Use of Modbus in RipEX. RipEX supports Modbus RTU, Modbus TCP as well as their combinations: Tab. 8.1: Centre protocol Remotes’ protocol Radio network behaviour Available with Operating mode 1 RTU RTU Modbus RTU over Radio channel Bridge, Router 1.1 Multiple Mas- RTU ters RTU Modbus RTU over Radio channel Router 2 TCP TCP TCP/IP protocol over Radio channel Bridge, Router 3 TCP TCP TCP/IP protocol locally between Modbus device Router and RipEX.
Modbus TCP/RTU In Router mode, set the COM port of your Master RipEX to Modbus (Mode of Connected device). To translate Modbus addresses to RipEX format and vice versa either use a mask (if RipEX addresses mirror the Modbus ones) or table. A table must be used if there are several Modbus slaves behind a single RipEX (RS485 or both COM1 and COM2). For more information refer to on-line help or chapter XX of the manual. In addition, set Modbus to Slave on all remote units.
Modbus TCP/RTU S M S ETH Modbus TCP ETH Modbus TCP ETH Modbus TCP S S ETH Modbus TCP ETH Modbus TCP Fig. 8.3: Modbus TCP 8.3. Modbus TCP, local TCP/IP connection Note - Only works in Router mode. TCP connection is established only locally between Modbus devices and the connected RipEX units. TCP protocol overhead is not transmitted over the Radio channel. Secured TCP/IP transfer is not necessary because in Router mode every packet in the Radio channel is acknowledged on every radio hop.
Modbus TCP/RTU • • Set Modbus TCP/RTU to On. Type the port number on which the connected Modbus TCP Master initiates communication, by default 504, into “My TCP Port” field. Select how you want to translate Modbus addresses to RipEX IP addresses (using mask or table). Set the UDP interface to Terminal server (TS1-TS5). Set the same TS for remote RipEX’s too. Select how you want to translate Modbus addresses to RipEX IP addresses (using mask or table). Set the UDP interface to Terminal server (TS1-TS5).
Modbus TCP/RTU • • Select the type of translation from Modbus to RipEX IP address (mask or table), as described in chapter 3. Set the UDP interface to COM1 or COM2 depending on the port that the remote RipEX uses to connect to the Slave device. To set up RipEX connected to Modbus RTU Slave: • As described in chapter 1 set the appropriate COM to Modbus and the Mode of Connected to Slave. 8.5.
Modbus TCP/RTU A Slave with Modbus RTU protocol may simultaneously communicate with masters using Modbus TCP and Modbus RTU. The network will deliver responses only to the Master which issued the queries using the appropriate protocol. The individual settings are described in chapters 1–5.
UNI protocol 9. UNI protocol UNI is the "Universal" protocol utility designed by RACOM. It is not a new SCADA protocol, it can actually process different protocols of different vendors. It supports both the standard MASTER -SLAVE and the MULTI MASTER types of communication. At least one Master is required in the network.
UNI protocol The 5th byte from the incoming message from SCADA centre is used to replace the last byte of the Base IP and the resulting IP address is used as the destination of the UDP datagram which contains the original SCADA message. Let assume that the content of 5th byte is 0x65 - then the IP destination address will be 10.0.0.101 and the UDP port 8882. The translation by a table is more versatile, however it requires an extra line of configuration for every remote in the network.
UNI protocol 9.2. MASTER – SLAVE with several Masters The behaviour of Master and Slave is exactly the same as in the previous scenario, i.e. a Slave always responds to the address from which the request was sent. If by chance two simultaneous requests from different Masters are received by a slave radiomodem, the RipEX radio modem waits for the first reply from the connected SCADA device before transmitting the request which arrived second. The 500 ms timeout applies again, i.e.
UNI protocol Note that, similarly to the MASTER-MASTER mode, the Poll Response Control at the Master RipEX has to be set to Off. 52 RipEX Application notes – © RACOM s.r.o.
Channel access 10. Channel access Method of accessing the radio channel may significantly affect the overall reliability of packet transmission. Even in a simple polling-type application, which never generates more than a single packet at a time, collisions may occur when repeaters are used. The goal of channel access is either to eliminate collisions completely, or to reduce their probability while ensuring that systematic repeated collisions never happen.
Channel access 10.2. Bridge mode In Bridge mode, a packet is transmitted to the radio channel immediately, without any checking whether the radio channel is occupied or not. If other radio was transmitting simultaneously, a collision would occur and both packets would be lost. Consequently Bridge mode can be used only for applications which never generate more than a single message at a time, e.g. master-slave polling applications.
Channel access First, packet A is broadcast from Radio 1. Radio 2 receives Packet A and sends it to its COM. In the instant when it starts the reception of Packet A, Radio 2 calculates (from information in the received packet header and from number of repeaters in its own setting) the time delay which is needed for the delivery of Packet A through the repeater (repeaters). When the response from the connected device arrives via COM (Packet B), the Radio 2 postpones its transmission for the delay.
Channel access 10.2.2. Time division of responses in Bridge mode There is also the Tx delay setting in the menu. It shall be used in Bridge mode if multiple RTUs connected to slave stations reply to a broadcast query from the centre. It is necessary to spread out their replies to the radio channel in terms of time, otherwise a massive collision occurs. It can be achieved by setting the TX delay parameter to an adequate sequence of TX delays (e.g.
Channel access t [ms] - time needed for the packet transmission n [ - ] - number of bytes transmitted (consider the longest possible reply from RTU) b [kbps] - Modulation rate fec [ - ] - Forward Error Correction fec = 1.00 if FEC = Off fec = 0.75 if FEC = On This calculation gives approximate results ( ± 3ms). When more accurate calculation is necessary, please check the calculation tool on Racom web pages http://www.racom.eu/eng/products/radio-modemripex.
Channel access 10.4. Router Mode 10.4.1. Channel access in Router mode The protocol in the radio channel in the Router mode of RipEX uses several methods to prevent and solve collisions. The first is Listen Before Transmit. Not a simple CSMA (Carrier Sensing Multiple Access), but a sophisticated LBT with configurable threshold. Only a valid data packet with RSS above threshold or a data packet destined for the RipEX itself is evaluated as a busy channel.
Channel access generates messages to non-existent or switched-off remotes (for any reason). When a remote site is without power (including the RipEX) and the centre continues sending requests to that remote, the last repeater will keep retransmitting these requests for full number of Retries set. More importantly, a long retransmission time-out at the application level is not desirable any more, since it keeps the centre from continuing the polling cycle.
Revision History Appendix A. Revision History Revision 1.1 First issue 2011-09-02 Revision 1.2 New chapter – UNI protocol 2012-01-31 60 RipEX Application notes – © RACOM s.r.o.
