Contemporary Research TD960801
Contents
1. 34 TD960801 0MC ll List of Figures Figure 2 1 Figure 2 2 Figure 2 3 Figure 2 4 Figure 2 5 Figure 2 6 Figure 2 7 Figure 2 8 Figure 2 9 Figure 2 10 DC POWeted ess scs eerseecientis dssigetdeaees dees 7 Redundant DC Powered eecceeseeeesteeeneeeeees 8 ING POWER eects teesebs testers eI NEET RE TES 8 AC Powered with Battery Backup eee 9 CAN Port Connector Assignments 1 0 0 0 10 Data Rate SWitChictssssciisssssastexncsccessavecsssovecesdebeees 11 Appropriate terminators are required at the ends of both the coaxial cable backbone and DeviceNet subnets 0 0 0 eee eeeeseeeseeereeeees 13 A maximum of eight EXTEND A BUSes can occupy one coaxial backbone segment before an active hub is required ee eee esseceseceeeeeeeeees 14 A 62 5 125 um duplex fiber optic cable is used on the FOG model up to a maximum of USS OQ MEt S nrnna eas 15 By using two AI3 CXS hubs a distributed star topology is achieved 17 TD960801 0MC iii 1 Introduction 1 1 Description The EXTEND A BUS for DeviceNet series of fieldbus extenders enable the geographic expansion of CAN based device networks such as DeviceNet by linking individual DeviceNet subnets together into a single larger network The medium arbitration method used by DeviceNet is intolerant of excessive signal delay Since cable length introduces delay DeviceNet networks tend to be distance limited Repeaters a2. Figure 2 8 A maximum of eight EXTEND A BUSes can occupy one coaxial backbone segment before an active hub is required Use BNC Tees and terminators when making connections One of each is included in the CXB model 2 6 2 Connecting Fiber Optic Cable FOG Multimode fiber optic cable is typically available in three sizes 50 125 62 5 125 and 100 140 The larger the size the more energy that can be launched and therefore the greater the distance Bayonet style ST connectors similar in operation to BNC coaxial cable connectors are provided for making the fiber connections Fiber optic connections require a duplex cable arrangement Two unidirectional cable paths provide the duplex link There are two devices on the EXTEND A BUS fiber port One device colored light gray is the transmitter and the other dark gray is the receiver Remember that light goes out of the light gray To establish a working link between an EXTEND A BUS and another EXTEND A BUS or an EXTEND A BUS to a hub the transmitter of point A must be connected to a receiver at point B Correspondingly the receiver at point A must be connected to a transmitter at point B This establishes the duplex link which is actually two simplex links Fiber optic cable is available paired for this purpose Usually the manufacturers labeling is only on one cable of the pair which is handy for identifying which of the two cables is which Establish your own protocol
3. TD960801 0MC 14 for connecting cable between hubs and EXTEND A BUSes in the field using the manufacturers labeling as a guide However remember that to connect point A to point B requires a paired fiber optic cable and that the light gray connector at one point must connect to a dark gray connector at the other point IEXTENDABUS EXTENDABUS O INK STATUS x fe Pa a T rus us E q E E g q g g 1 q Lo svat o Io Figure 2 9 A 62 5 125 um duplex fiber optic cable is used on the FOG model up to a maximum of 1830 meters TD960801 0MC 15 2 6 3 Extending the Backbone The backbone side of the EXTEND A BUS must comply with standard ARCNET cabling rules Companion AI ARCNET active hubs are available for extending the backbone cabling up to 6 km using coaxial cabling and ten active hubs When using a fiber optic backbone a maximum of 4 8 km can be achieved requiring two active hubs Hubs can be cascaded to reach the required distance By using active hubs star and distributed star topologies are possible There is however a limit to the overall length of the backbone network The delay experienced when an EXTEND A BUS communicates to another EXTEND A BUS with each located at the extreme ends of a network cannot exceed 31 us This delay is due to cable
4. CAN compliant devices on the complete network have unique MAC IDs 3 2 2 ARCNET Port On the coaxial cable model a BNC connector has been provided On the fiber optics model two ST connectors are provided one for transmit TX and one for receive RX The coaxial port is of the high impedance type CXB allowing for up to eight devices on one coaxial cable segment A BNC terminator BNC TER and a BNC Tee connector BNC T are provided to facilitate connections to other bridges on the ARCNET backbone The ARCNET port operates at 2 5 Mbps Each EXTEND A BUS requires a unique ARCNET node ID which has no meaning to the CAN segments Node ID s are automatically assigned by the EXTEND A BUSes themselves using an arbitration scheme upon power up TD960801 0MC 21 3 2 3 Topologies CAN based device networks usually operate over a multidrop topology with provisions for short drops of typically six meters each The trunk length depends upon the data rate and at 500 kbps the maximum length of the trunk is 100 meters Conceptually the multidrop topology is easy to understand and appears easy to implement and for many applications this is true However for some machines or processes the star or distributed star topology would reduce wiring especially when devices are clustered in all directions from the main control panel By incorporating bridges the multidrop topology is maintained since the ARCNET side of the bridges are bused howev
5. CAN port consists of a Intel 82527 CAN controller and isolated 82C251 transceiver The CAN port is capable of generating interrupts at a high speed since the EXTEND A BUS must listen to all CAN traffic Back to back CAN data frames can generate an interrupt every 94 us at 500 kbps The ARCNET buffers will also generate interrupts making low latency interrupt handling a priority for the EXTEND A BUS Included in the engine is a 128Kx8 FLASH ROM and 128Kx8 SRAM An internal serial port is used to update the firmware 3 3 System Considerations There are some design considerations when implementing a remote bridging system By its very nature of storing and forwarding messages the EXTEND A BUS system introduces additional signal latency which may disturb DeviceNet systems with tight timing constraints With the DeviceNet protocol there has been little evidence of any timing problems However the potential exists for a system to erroneously signal a failed response to an action when short cabling delays are assumed On systems with very fast DeviceNet scanners while operating at low data rates and lightly load systems the possibility exists for the master to issue a comment to a slave and fail to wait for the slave s response before issuing another command assuming a failed response This is especially true for devices that support long fragmented messages The solution is to increase the interscan time to either 5 to 10 ms in order to allow
6. The maximum segment distances are based upon nominal cable attenuation figures and worst case transceiver power budgets Assumptions are noted When approaching the maximum limits a link loss budget calculation is recommended When calculating the maximum number of nodes on a bus segment do not count the hub ports that terminate the bus segments nodes Do consider the maximum length of the bus segment to include the cable attached to the hub ports The CXB transceiver requires a minimum distance between nodes Adhere to this minimum since unreliable operation can occur TD960801 0MC 31 Appendix A continued Permissible Cable Lengths and Nodes Per Segment Trans ceiver Description Cable Connectors CXS coaxial star RG 62 u BNC CXB coaxial bus RG 62 u BNC FOG duplex fiberoptic 50 125 ST FOG duplex fiberoptic 62 5 125 ST FOG duplex fiber optic 100 140 ST This represents the minimum distance between any two nodes or between a node and a hub May require a jumper change on the EXTEND A BUS to achieve this distance Table A 1 Permissible Cable Length and Nodes Per Segment TD960801 0MC 32 2 5 Mbps Cable Length Max Nodes Min Max Bus Segment Notes 0 2000 ft 610 m N A 5 5 dB 1000 ft max 6 ft 2 m 1000 ft 305 m 8 5 5 dB 1000 ft max 0 3000 ft 915m N A 4 3 dB km max 0 6000 ft 1825 m N A 4 3 dB km max 0 9000 ft 2740m N A 4 0 dB km max TD960801 0MC 33 Appendix B De
7. and hub delays This delay translates to a maximum of 6 km of coaxial cable or 4 8 km of fiber optic cable When making this calculation only consider the distance between the two furthest EXTEND A BUSes Also verify the distance limitations of active hubs being used Active hubs that incorporate coaxial star ports CXS allow for 2000 foot connections between compatible ports but no bussing When making a connection to a CXS port from the EXTEND A BUS CXB port make sure that the CXS port is located at one end of the segment and that no terminator is used The length of a segment connecting a CXB port cannot exceed 1000 feet 305 m TD960801 0MC 16 610m Figure 2 10 By using two AI3 CXS hubs a distributed star topology is achieved Note that the hub to hub distance can be a maximum of 610 m when using coaxial cable and that no terminators are used at the AI3 ports However the cables to the EXTEND A BUSes still cannot exceed 305 m TD960801 0MC 17 TD960801 0MC 18 3 Operation 3 1 CAN Communications CAN was designed by Bosch and is currently described by ISO 11898 In terms of the Open Systems Interconnection model OSD CAN partially defines the services for layer 1 physical and layer 2 data link Other standards such as Devic
8. the tests The three classes of performance are defined by CCSI as follows Class A Normal operation however occasional reconfigurations may occur or throughput may be reduced due to an error recovery algorithm by the ARCNET data link level protocol Class B Throughput reduced to zero and continuous reconfigurations occur Normal operation resumed after offending signal removed Class C Complete loss of function Unit resets and normal operation restored without human intervention At no time did the EXTEND A BUS fail to return to normal operation or become unsafe during the execution of these tests A copy of the Declaration of Conformity is in the appendix 2 3 Mounting the EXTEND A BUS The EXTEND A BUS is intended for mounting onto a vertical panel within an industrial control enclosure Two 8 screws can be used for mounting the EXTEND A BUS in a vertical orientation Refer to the mechanical specifications for details To mount the EXTEND A BUS onto a DIN rail an optional DIN rail mounting clip AI DIN must be purchased and installed on the rear of the EXTEND A BUS Once the clip is mounted to the EXTEND A BUS the EXTEND A BUS can be snapped onto the DIN rail 2 4 Powering the EXTEND A BUS The EXTEND A BUS requires either low voltage AC or DC power in order to operate Consult the specifications for power requirements Power is provided to a four pin removable keyed TD960801 0MC 6 connector There are se
9. EXTEND BUS for DeviceNet A Line of Fieldbus Extenders for DeviceNet User Manual TD960801 OMC CONTEMPORARY ON TROLS Trademarks Contemporary Controls ARC Control ARC DETECT and EXTEND A BUS are trademarks or registered trademarks of Contemporary Control Systems Inc ARCNET is a registered trademark of Datapoint Corporation Other product names may be trademarks or registered trademarks of their respective companies TD960801 OMC Revised 07 16 02 Copyright Copyright April 1999 2002 by Contemporary Control Systems Inc All rights reserved No part of this publication may be reproduced transmitted transcribed stored in a retrieval system or translated into any language or computer language in any form or by any means electronic mechanical magnetic optical chemical manual or otherwise without the prior written permission of Contemporary Control Systems Inc 2431 Curtiss Street Downers Grove Illinois 60515 USA Tel 1 630 963 7070 Fax 1 630 963 0109 E mail info ccontrols com WWW http www ccontrols com Contemporary Controls Ltd Sovereign Court Two University of Warwick Science Park Sir William Lyons Road Coventry CV4 7EZ UK Tel 44 0 24 7641 3786 Fax 44 0 24 7641 3923 E mail info ccontrols co uk Disclaimer Contemporary Control Systems Inc reserves the right to make changes in the specifications of the product described within this manual at any time without not
10. bs are available for extending the backbone cabling up to 6 km using coaxial cabling and ten active hubs When using a fiber optic backbone a maximum of 4 8 km can be achieved requiring two active hubs Hubs are cascaded to reach the required distance 1 2 Features e Extends the length of DeviceNet networks up to 6 km e Fully DeviceNet compliant e Fiber optic or coaxial cabling e Star bus or distributed star topology e Variable data rate up to 500 kbps e Low voltage AC or DC powered e Panel mount enclosure 1 3 Specifications Electrical DC AC Input voltage 10 36 volts 8 24 volts Input power 4 watts AVA Input frequency N A 47 63 Hz Power Options DC powered Redundant powered AC powered AC powered with battery backup TD960801 0MC 2 Environmental Operating 0 C to 60 C Storage 40 C to 85 C Functional Data latency 1 2 ms typical per EXTEND A BUS pair Regulatory Compliance FCC Part 15 Class A CE Mark 1 4 Port Specifications CAN Port Compliance DeviceNet Volume I Release 2 0 Data Rate 125 kbps 250 kbps 500 kbps select able or Autobaud 125 kbps 250 kbps 500 kbps LEDs CAN status Module status network status Transceivers Optically isolated 82C251 Cable DeviceNet Thick Connectors 5 position Open pluggable Maximum segment 125 kbps 500 meters 1640 ft or subnet distance 250 kbps 250 meters 820 ft 500 kbps 100 meters 328 ft Maximum number of nodes per seg
11. c by restricting data only to stations specified in the transmission that reside on the network controlled by the bridge This blocking is difficult to implement in broadcast networks such as CAN and therefore not recommended Bridges are ignorant of the higher level protocols sent over CAN since bridges operate at the data link layer Therefore protocols such as DeviceNet Smart Distributed System and CANopen are passed without modification 3 2 Theory of Operation The EXTEND A BUS is classified as a remote bridge and contained in a two piece metal enclosure suitable for panel TD960801 0MC 20 mounting into a larger industrial enclosure As an option the EXTEND A BUS can be DIN rail mounted by purchasing the appropriate kit The EXTEND A BUS has two ports one for the CAN network and the other for the ARCNET backbone The device can be powered from either a low voltage AC or DC power supply 3 2 1 CAN Port One electrically isolated CAN port has been provided capable of operating to the DeviceNet physical layer specification This was done to minimize ground loop problems while providing isolation to the ARCNET backbone The port conforms to the DeviceNet specification for a five position unsealed connector One CAN segment conforming to the electrical restrictions of the CAN segment attaches to this port In a similar method additional CAN segments are attached to other EXTEND A BUS CAN ports The only restriction is that all
12. claration of Conformity Applied Council Directives Electromagnetic Compatibility Directive 89 336 EEC Council Directive as amended by Council Directive 92 31 EEC amp Council Directive 93 68 EEC Standard to which Conformity is Declared EN 55022 1995 CISPR22 1993 Class A Limits and Methods of Measurement of Radio Disturbance Characteristics of Information Technology Equipment EN 50082 2 1995 Electromagnetic Compatibility Generic Immunity Standard Part 2 Industrial Environment Manufacturer Contemporary Control Systems Inc 2431 Curtiss Street Downers Grove IL 60515 USA Authorized Representative Contemporary Controls Ltd Sovereign Court Two University of Warwick Science Park Sir William Lyons Road Coventry CV4 7EZ UNITED KINGDOM TD960801 0MC 34 Type of Equipment Industrial network extender Directive EB DNET CXB EB DNET FOG Technical File TD960801 0FA I the undersigned hereby declare that the product s specified above conforms to the listed directives and standards George M Thomas President April 6 1999 TD960801 0MC 35
13. dequate padding and shock absorbing properties are used CC is not responsible for any damage incurred from improper packaging Shipments should be insured for your protection TD960801 0MC 29 Ship the product freight prepaid to the location from which it was purchased Contemporary Control Systems Inc 2431 Curtiss Street Downers Grove IL 60515 U S A Contemporary Controls Ltd Sovereign Court Two University of Warwick Science Park Sir William Lyons Rd Conventry CV4 7EZ U K TD960801 0MC 30 Appendices Appendix A Permissible Segment Lengths A segment is defined as any portion of the complete ARCNET cabling system isolated by one or more hub ports On a hubless or bus system the complete ARCNET cabling system consists of only one segment with several nodes however a system with hubs has potentially many segments An ARCNET node is defined as a device with an active ARCNET controller chip requiring an ARCNET device address Active and passive hubs do not utilize ARCNET addresses and therefore are not nodes Each segment generally supports one or more nodes but in the case of hub to hub connections there is the possibility that no node exists on that segment The permissible cable length of a segment depends upon the transceiver used and the type of cable installed Table A 1 provides guidance on determining the constraints on cabling distances as well as the number of nodes allowed per bus segment
14. eNet Smart Distributed System and CANopen collectively called higher layer protocols build upon the basic CAN specification and define additional services of the seven layer OSI model Since all of these protocols utilize CAN integrated circuits they therefore all comply with the data link layer defined by CAN CAN specifies the medium access control MAC and physical layer signaling PLS as it applies to layers 1 and 2 of the OSI model Medium access control is accomplished using a technique called non destructive bit wise arbitration As stations apply their unique identifier to the network they observe if their data is being faithfully produced If it is not the station assumes that a higher priority message is being sent and therefore halts transmission and reverts to receiving mode The highest priority message gets through and the lower priority messages are resent at another time The advantage of this approach is that collisions on the network do not destroy data and eventually all stations gain access to the network The problem with this approach is that the arbitration is done on a bit by bit basis requiring all stations to hear one another within a bit time actually less than a bit time At a 500 kbps bit rate this time is less than 2000 ns which does not allow much time for transceiver and cable delays The result is that CAN networks are usually quite short and frequently less than 100 meters in length at higher speeds To
15. each weekday except holidays between 8 00 a m and 5 00 p m United Kingdom time If you have a problem outside these hours leave a voice mail message in the CC after hours mailbox after calling our main phone number You can also fax your request by calling 1 630 963 0109 U S or 44 0 24 7641 3923 U K or contact us via e mail at info ccontrols com or info ccontrols co uk You can visit our web site at www ccontrols com When contacting us please leave a detailed description of the problem We will contact you by phone the next business day or in the manner your instructions indicate We will attempt to resolve the problem over the phone If unresolvable the customer will be given an RMA number in order that the product may be returned to CC for repair Warranty Repair Products under warranty that were not subjected to misuse or abuse will be repaired at no charge to the customer The customer however pays for shipping the product back to CC while CC pays for the return shipment to the customer CC normally ships ground International shipments may take longer If the product has been determined to be misused or abused CC will provide the customer with a quotation for repair No work will be done without customer approval TD960801 0MC 28 Non Warranty Repair CC provides a repair service for all its products Repair charges are based upon a fixed fee basis depending upon the complexity of the product Therefore Custo
16. empt to determine the data rate by observing the traffic on the CAN port Therefore it is important that the CAN port be connected to the DeviceNet subnet connecting the master controller All other EXTEND A BUSes should have their Data Rate switch set to S slave position since their data rate will be set by the master EXTEND A BUS the one connected to the master which will broadcast the required data rate to all slaves once the data rate is determined Autobauding functions for the three data rates 125 250 and 500 kbps TD960801 0MC 11 2 6 Connecting to the Backbone Port The backbone link port is ARCNET compliant and therefore complies with the cabling rules for ARCNET networks For more information on designing an ARCNET cabling system refer to Contemporary Controls publication ARCNET Tutorial amp Product Guide Either of two transceivers are available on the backbone port The coaxial bus CXB transceiver requires coaxial cable allowing a total of eight EXTEND A BUS devices to be connected onto one wiring segment The fiber optic FOG transceiver allows for two EXTEND A BUSes to be connected in a point to point or link fashion If star or distributed star topologies are desired or if the cabling distances must exceed the basic specifications ARCNET compliant active hubs are required Contemporary Controls provides two series of active hubs the MOD HUB series of modular hubs and the AI series of fix port
17. er since each CAN segment attached to a bridge can comply with the maximum capabilities of the CAN segment a system is created with a long ARCNET trunk of 1000 feet and eight long CAN drop segments of 330 feet each If a true star topology or longer distances are desired each EXTEND A BUS can be connected to a companion AI series active hub For distributed star topologies multiple AI series active hubs can be cascaded up to the ARCNET limit of four miles when using coaxial cable With increased distances comes increased signal latency and potential real time performance degradation of the network 3 2 4 Power Requirements Either low voltage AC or DC power will power the EXTEND A BUS A DC DC converter accepts the input power and converts it to 5 volts DC for use by the EXTEND A BUS The AC power must come from a floating secondary in the range of 8 to 24 volts AC The DC power source must be in the range of 10 to 36 VDC Power connections are derived from a four position unsealed connector The CAN port must still be powered from the network itself since the EXTEND A BUS does not serve as a network power supply however the EXTEND A BUS can be powered from the 24 volt network power supply TD960801 0MC 22 3 2 5 EXTEND A BUS Engine A high speed 32 Mhz 80C188 microprocessor provides the computing power for the EXTEND A BUS The ARCNET port consists of a 20020 controller chip and coaxial bus or fiber optic transceiver The
18. his warranty does not cover repair of products that have been damaged by abuse accident disaster misuse or incorrect installation CC s limited warranty covers products only as delivered User modification may void the warranty if the product is damaged during installation of the modifications in which case this warranty does not cover repair or replacement This warranty in no way warrants suitability of the product for any specific application IN NO EVENT WILL CC BE LIABLE FOR ANY DAMAGES INCLUDING LOST PROFITS LOST SAVINGS OR OTHER INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PRODUCT EVEN IF CC HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES OR FOR ANY CLAIM BY ANY PARTY OTHER THAN THE PURCHASER THE ABOVE WARRANTY IS IN LIEU OF ANY AND ALL OTHER WARRANTIES EXPRESSED OR IMPLIED OR STATUTORY INCLUDING THE WARRANTIES OF MERCHANTABILITY FITNESS FOR PARTICULAR PURPOSE OR USE TITLE AND NONINFRINGEMENT TD960801 0MC 27 Repair or replacement as provided above shall be the purchaser s sole and exclusive remedy and CC s exclusive liability for any breach of warranty Technical Support Contemporary Controls U S A will provide technical support on its products by calling 1 630 963 7070 each weekday except holidays between 8 00 a m and 5 00 p m Central time Contemporary Controls Ltd U K will provide technical support on its products by calling 44 0 24 7641 3786
19. hubs Refer to the appendix for more information on active hubs 2 6 1 Connecting Coaxial Bus Networks CXB Coaxial bus backbone ports must be interconnected with RG 62 u 93 ohm coaxial cable In a simple two EXTEND A BUS arrangement a BNC Tee BNC T is twisted onto each BNC backbone port A length of RG 62 u cable no shorter than 6 feet 2 m nor longer than 1000 feet 305 m is connected between the BNC Tee connectors At the open end of each BNC Tee is connected a 93 ohm terminator BNC TER This completes the basic connection TD960801 0MC 12 6 6 EXTENDABUS EXTENDABUS LINK STATUS LINK STATUS i 1m SHIELD i 2 Fi A leo aeaa Figure 2 7 Appropriate terminators are required at the ends of both the coaxial cable backbone and DeviceNet subnets More than two EXTEND A BUSes but no more than eight can be connected to one wiring segment Insert the desired number of EXTEND A BUSes using BNC Tee connectors to the backbone wiring Make sure that any two EXTEND A BUSes are separated by at least 6 foot 2 m of cable and that the complete cabling segment does not exceed 1000 feet 305 m TD960801 0MC 13 F ee A mrcmor Co M a ay ra K 1 I l
20. ice and without obligation of Contemporary Control Systems Inc to notify any person of such revision or change TD960801 0MC i Contents Chapter 1 Chapter 2 Chapter 3 Chapter 4 Appendices Introduction sssssissssssssissssssssssssscsssssc sssrsssosssssissssse 1 Ii DeScription seesisenerniesinieneninineiins 1 We2 Features 2 vic coeisdecsetd iecssiddanednsdassinstedessieionss 2 1 30 SpOCifCatiOMs secsec 2 1 4 Port Specifications ssserpiccsresissonssiseris 3 1 5 Ordering Information s es 4 Installation scssssssissssssssisssssssssssssssssssssssssssssscsssissssss 5 Dele Introductio ssiri seisine 3 2 2 Electromagnetic Compliance 5 2 3 Mounting the EXTEND A BUS 0 0 6 2 4 Powering the EXTEND A BUS aaee 6 2 5 Connecting to the CAN Port oe 9 2 6 Connecting to the Backbone Port 12 OPCLALION sissicisssssccsnssasenconestoosssessesonstsvsesesvoossses 19 3 1 CAN Communications 0 0 0 eee 19 3 2 Theory of Operation eee eeeeeeee 20 3 3 System Considerations 0 0 0 eee 23 34 LED Indicatofs iecteviscssescneterssescsrssteees venseee 25 ee 27 WALT ANY ssssveceestinvctesdiscevertinasebsinecvertinessicswveseeyies 27 Technical S ppott acisini eiiiai iinei 28 Warranty Repalll sccsvsssscsvesssciesstsetsscssieessenstevesceess 28 Non Warranty Repair eessen 29 Returning Products for Repair cee 29 Appendix A Permissible Segment Lengths 31 Appendix B Declaration of Conformity
21. increase this distance either the data rate is decreased or additional equipment is required TD960801 0MC 19 3 1 1 Repeaters The usual approach to increasing network distance is to use repeaters Repeaters provide signal boost to make up the loss of signal strength on a long segment However the problem with long CAN segments is usually not lack of signal strength but excessive signal latency This latency is due to the propagation delay introduced by the transceivers and twisted pair wiring If this latency approaches one bit time the non destructive bit wise arbitration mechanism fails Repeaters actually introduce more delay due to the additional electronics and are not effective in increasing the overall length of CAN networks Repeaters are generally used to increase the effective length of drop cables from CAN trunk lines Repeaters operate on the physical layer 3 1 2 Bridges Bridges are defined as devices that link two similar networks however bridges can mean different things to different people so further clarification is necessary A local bridge stands by itself connecting adjacent wiring segments together as in the case of a repeater Remote bridging interconnects two physically separated but similar networks together using a different interconnecting medium Therefore a pair of bridges are required to interconnect two networks the way two modems are used on leased phone lines Sometimes bridges block network traffi
22. is commissioned however no CAN data has been received in over a second 3 4 2 LINK Status LED A dual color LED yel green is used to identify status of the ARCNET backbone port After a power on sequence the LED indications are as follows YELLOW Continuous network configuration occurring or no other EXTEND A BUS nodes found Flashing YELLOW One or more network reconfigurations detected on an operating network GREEN Data is being received from the network Flashing GREEN Network is operational however no data is being received from the network in the last second 3 4 3 Power on LED Sequence The CAN Status and LINK Status LEDs are sequenced upon power up to verify the integrity of the LEDs The sequence is as follows CAN status off and Link status off CAN status GREEN for 0 25 seconds CAN status RED for 0 25 seconds LINK status GREEN for 0 25 seconds LINK status YELLOW for 0 25 seconds After the power on sequence both LEDs assume their normal operation TD960801 0MC 26 4 Service Warranty Contemporary Controls CC warrants its product to the original purchaser for one year from the product s shipping date If a CC product fails to operate in compliance with its specification during this period CC will at its option repair or replace the product at no charge The customer is however responsible for shipping the product CC assumes no responsibility for the product until it is received T
23. lexible ARCNET cabling options Do not cascade EXTEND A BUSes beyond two since the delay stackup could be excessive Instead connect all EXTEND A BUSes in a star topology using a hub thereby reducing data latency to that of two EXTEND A BUSes Implementing fiber optics over any reasonable distance with CAN is difficult due to the increased delays caused by the additional circuitry However fiber optic ARCNET solutions are readily available Therefore the benefits of fiber optics can be gained simply by adding remote bridges Note that the propagation delay of fiber optic cable 5 ns m is 25 more than that of coaxial cable This is important when calculating ARCNET delay margin and was considered when setting the 4 8 km fiber optic limit 3 4 LED Indicators One CAN Status LED and one LINK Status LED are provided in order to convey information regarding their respective ports When LEDs flash they will flash approximately at a rate of 0 5 seconds on and 0 5 seconds off 3 4 1 CAN Status LED A dual color LED red green is used to identify status of the CAN port After a power on sequence the LED indications are as follows TD960801 0MC 25 RED The EXTEND A BUS has detected an internal problem with the CAN port requiring service Flashing RED The CAN port does not have sufficient voltage on its V and V lines to power the optically isolated port GREEN The CAN port is receiving data Flashing GREEN The CAN port
24. ment 64 Terminating resistor 121 ohms Backbone Port Compliance ARCNET ANSI ATA 878 1 Data Rate 2 5 Mbps TD960801 0MC 3 LEDs Transceivers Cable Connectors Maximum segment or subnet distance Maximum number Link status Reconfiguration status activity status CXB model FOG model CXB model FOG model CXB model FOG model CXB model FOG model CXB model of nodes per segment FOG model Terminating resistor CXB model FOG model 15 Ordering Information transformer coupled 850 nm duplex fiber optic RG 62 u coaxial 62 5 125 um duplex fiber optic BNC ST 305 meters 1000 ft 1830 meters 6000 ft optical power budget 10 4dB 8 N A 93 ohms N A The EXTEND A BUS series is available in several configurations depending upon the application and cable media supported EXTEND A BUSes EB DNET CXB EXTEND A BUS with coaxial bus backbone EB DNET FOG EXTEND A BUS with fiber optic backbone Accessories AI XFMR AI XFMR E AI DIN BNC T BNC TER TD960801 0MC 4 Wall mount transformer 120 VAC nom Wall mount transformer 240 VAC nom DIN rail mounting kit BNC T connector 93 ohm BNC terminator 2 Installation 2 1 Introduction The EXTEND A BUS series is intended to be panel mounted into an industrial enclosure or into a wiring closet Two 8 pan head screws not provided are required for mounting Optionally the bridge can be mounted o
25. mer Service can provide a quotation on the repair cost at the time a Returned Material Authorization RMA is requested Customers pay the cost of shipping the defective product to CC and will be invoiced for the return shipment to their facility No repair will be performed without customer approval If a product is determined to be unrepairable the customer will be asked if the product can be replaced with a refurbished product assuming one is available Under no circumstances will CC replace a defective product without customer approval Allow ten working days for repairs Returning Products for Repair To schedule service for a product please call CC Customer Service support directly at 1 630 963 7070 U S or 44 0 24 7641 3786 U K Have the product model and serial number available along with a description of the problem A Customer Service representative will record the appropriate information and issue via fax an RMA number a code number by which we track the product while it is being processed Once you have received the RMA number follow the instructions of the Customer Service support representative and return the product to us freight prepaid with the RMA number clearly marked on the exterior of the package If possible reuse the original shipping containers and packaging In any event be sure you follow good ESD control practices when handling the product and ensure that antistatic bags and packing materials with a
26. n a DIN rail by purchasing a DIN rail mounting kit 2 2 Electromagnetic Compliance The EXTEND A BUS series complies with Class A radiated and conducted emissions as defined by FCC part 15 and EN55022 This equipment is intended for use in non residential areas Refer to the following notices in regard to the location of the installed equipment Note This equipment has been tested and found to comply with the limits for a Class A digital device pursuant to Part 15 of the FCC Rules These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment This equipment generates uses and can radiate radio frequency energy and if not installed and used in accordance with the instruction manual may cause harmful interference to radio communications Operation of this equipment in a residential area is likely to cause harmful interference in which case the user will be required to correct the interference at his own expense Warning This is a Class A product as defined in EN55022 In a domestic environment this product may cause radio interference in which case the user may be required to take adequate measures TD960801 0MC 5 The EXTEND A BUS has been tested to EN50082 Generic Immunity Standard Industrial Environment This standard identifies a series of tests requiring the equipment to perform to a particular level during or after the execution of
27. ors are required at the ends of trunk cables If the EXTEND A BUS is located at the end of a trunk and no terminator is present a discrete resistor terminator 121 ohms can be connected under the screw terminals for CAN_H and CAN_L Refer to Figure 2 5 for wiring details Network Connector Female Contacts 5 V red 4 CANH white 3 drain bare 2 CANL blue 1 FA 3 4 5 1 V black Device Connector Male Contacts Figure 2 5 CAN Port Connector Assignments 2 5 2 CAN Port Data Rates Several data rates can be selected by a rotary switch as shown in figure 2 6 Switch positions are labeled A S 125 250 500 A and S are used to implement autobauding which will be discussed later The remaining positions determine a fixed data rate in units of kbps Therefore the lowest rate is 125 kbps and the highest is 500 kbps The data rate switch is only read upon power up so to change settings the switch position should be changed and the power cycled to the EXTEND A BUS A clockwise rotation increases the data rate setting TD960801 0MC 10 S KC 125 DATA RATE dk 230 kbps s 500 A Figure 2 6 Data Rate Switch 2 5 3 Autobauding Autobauding is the action of automatically matching the data rate of the EXTEND A BUS to the data rate of a master controller or scanner in a DeviceNet network By moving the Data Rate switch to the A position and powering up the EXTEND A BUS the EXTEND A BUS will att
28. re ineffective in extending distances since they introduce additional delay On the other hand fieldbus extenders like EXTEND A BUS solve the problem by segmenting a single DeviceNet network into manageable subnets EXTEND A BUS interconnects two physically separated but similar networks using a different interconnecting medium Thus a pair is required to interconnect two networks or subnets the way two modems are used on leased phone lines Utilizing ARCNET as the high speed deterministic interconnecting medium the EXTEND A BUS captures DeviceNet traffic and replicates it to the receiving device The receiving device removes DeviceNet data and rebroadcasts the data to its attached DeviceNet subnet EXTEND A BUS does not filter out DeviceNet identifiers or MAC addresses so DeviceNet messages are rebroadcast unmodified Application Information Each EXTEND A BUS creates a DeviceNet subnet and a minimum of two EXTEND A BUSes is required to establish a network The data rate on each subnet can be different from the other subnets DeviceNet identifiers or MAC ID checks are replicated on all subnets EXTEND A BUS pairs are best viewed as an extension cord Each EXTEND A BUS does not consume a permanent MAC ID and therefore is transparent to the network TD960801 0OMC 1 Extending the Interconnecting Medium or Backbone The backbone side of the EXTEND A BUS must comply with standard ARCNET cabling rules Companion AI ARCNET active hu
29. s a master for all other bridges on the network functioning as slaves The master EXTEND A BUS must be connected to the CAN segment connected to the master controller As the master controller transmits data the master EXTEND A BUS determines the data rate and informs all other EXTEND A BUSes the required data rate over the ARCNET connection Once the data rates are determined traffic is sent between the bridges functioning as one long extension cord The EXTEND A BUS data rates can be manually set by way of a switch and there is no inherent reason why individual CAN segments cannot be set to different data rates Using the same extension cord analogy it would appear that a remote bridging system must be powered before or at the same time as the slave devices or master controller in order that all devices can execute initialization routines such as duplicate TD960801 0MC 24 MAC ID tests as in the case of DeviceNet However if a remote bridge loses power while all other devices remain powered the failure mode should be no different than cutting the cable in the middle of a CAN segment When power is restored to the remote bridges the restart sequence should be the same as if the maintenance person reconnected a disconnected cable CAN networks are usually configured in a bus or multidrop topology while ARCNET can be configured as a bus star or distributed star topology Therefore CAN implementations can take advantage of the more f
30. sufficient time for response Another solution is to increase the data rate on all devices to 500 kbps Still another solution is to move problem devices to the local segment the same segment as the scanner in order to eliminate delays due to the EXTEND A BUSes TD960801 0MC 23 Within a CAN segment at least one device must acknowledge the valid receipt of another device s transmission That acknowledgment however does not extend beyond an EXTEND A BUS Even though a successful transmission occurred on a CAN segment that transmission must be replicated on all other CAN segments generating additional acknowledgments Therefore it is possible that a replicated transmission on one CAN segment may fail due to a cabling problem resulting in no acknowledgment while all other CAN segments view the transmission successful However the DeviceNet protocol does not rely upon the CAN data link acknowledgment as sole indication of a successful transmission Additional error checking has been incorporated in the upper layer DeviceNet protocol Single nodes can operate on an individual CAN segment with remote bridging Since each EXTEND A BUS has one internal CAN chip this CAN chip acknowledges the single node s message Without remote bridges a single node will fail to hear an acknowledgment and will continuously retry The DeviceNet protocol supports autobauding which is possible for the EXTEND A BUS to implement One EXTEND A BUS acts a
31. the capability of delivering up to 4 VA of apparent power The secondary of the transformer must not be grounded For convenience two auxiliary power supplies are available e AI XFMR for 120 VAC primary power e AI XFMR E for 240 VAC primary power Reference Figure 2 3 Figure 2 3 AC Powered TD960801 0MC 8 2 4 4 AC Powered with Battery Backup The EXTEND A BUS can also be powered from both an AC and DC power source Usually the DC source is from a battery supply which is connected as the DC powered option Refer to Figure 2 4 In this application the EXTEND A BUS does not charge the battery so separate provisions are required for charging If the AC source fails the EXTEND A BUS will operate from the battery source Cue a ae Figure 2 4 AC Powered with Battery Backup 2 5 Connecting to the CAN Port The CAN port complies to the DeviceNet physical layer specification for an isolated port Since the port is isolated bus power V V must be present in order for the port to function A bus power sensor has been provided in the EXTEND A BUS to ensure that in the absence of bus power the port will not enter the bus off state 2 5 1 CAN Port Assignments A five position open style male connector has been provided on the EXTEND A BUS for connections See figure 2 5 for connector assignments A mating female connector has been provided in order to make field connections TD960801 0MC 9 Terminat
32. veral methods for providing power These methods are DC powered redundant DC powered AC powered and AC powered with battery backup 2 4 1 DC Powered Make connections as shown in Figure 2 1 The EXTEND A BUS incorporates a DC DC converter that accepts a wide voltage range 10 36 VDC and converts the voltage for internal use Input current varies with input voltage so it is important to size the power conductors accordingly Input power to the EXTEND A BUS maximizes at 4 watts therefore at 10 VDC the input current is approximately 400 ma The ground connection to the EXTEND A BUS is connected to chassis within the EXTEND A BUS The input connections are reverse voltage protected Figure 2 1 DC Powered 2 4 2 Redundant DC Powered Redundant diode isolated DC power inputs are provided on the EXTEND A BUS for those applications in which there is a concern that the EXTEND A BUS remain operational in the event of a primary power failure Make connections as shown in Figure 2 2 Each power supply source must be sized for the full 4 watt load of the EXTEND A BUS Do not assume that input currents will be balanced from the two supplies TD960801 0MC 7 Figure 2 2 Redundant DC Powered 2 4 3 AC Powered If only AC power is available the EXTEND A BUS can be powered by the secondary of a low voltage transformer whose primary is connected to the AC mains The secondary voltage must be in the range of 8 to 24 VAC 47 63 Hz with
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