EXTEND-A-BUS for A Line of Fieldbus Extenders for DeviceNet User Manual #TD960801-0MC
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. TD960801-0MC Revised 07-16-02 Copyright © Copyright April 1999-2002 by Contemporary Control Systems, Inc. All rights reserved.
Contents Chapter 1 Introduction ......................................................... 1 1.1 Description ................................................ 1 1.2 Features ..................................................... 2 1.3 Specifications ............................................ 2 1.4 Port Specifications .................................... 3 1.5 Ordering Information ................................ 4 Chapter 2 Installation ........................................................... 5 2.
List of Figures Figure 2-1 DC Powered ........................................................ 7 Figure 2-2 Redundant DC Powered ...................................... 8 Figure 2-3 AC Powered ........................................................ 8 Figure 2-4 AC Powered with Battery Backup ...................... 9 Figure 2-5 CAN Port Connector Assignments ................... 10 Figure 2-6 Data Rate Switch ..............................................
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.
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 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 are cascaded to reach the required distance. 1.
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 Compliance Data Rate able Autobaud LEDs Transceivers Cable Connectors Maximum segment or subnet distance CAN Port DeviceNet Volume I, Release 2.
Link status: Reconfiguration status/activity status Transceivers -CXB model: transformer coupled -FOG model: 850 nm duplex fiber optic Cable -CXB model: RG-62/u coaxial -FOG model: 62.5/125 µm duplex fiber optic Connectors -CXB model: BNC -FOG model: ST Maximum segment -CXB model: 305 meters (1000 ft) or subnet distance -FOG model: 1830 meters (6000 ft) (optical power budget 10.
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 on 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.
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 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.
connector. There are several 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-ABUS 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.
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 the capability of delivering up to 4 VA of apparent power. The secondary of the transformer must not be grounded.
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. Figure 2-4. AC Powered with Battery Backup 2.
Terminators 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) 1 2 3 4 5 5 V+ red 4 CAN_H white 3 drain bare 2 CAN_L blue 1 V- black Device Connector (Male Contacts) Figure 2-5. CAN Port Connector Assignments 2.5.
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 attempt 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.
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 & 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.
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-ABUSes are separated by at least 6 foot (2 m) of cable and that the complete cabling segment does not exceed 1000 feet (305 m).
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.
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. Figure 2-9. A 62.5/125 µm duplex fiber optic cable is used on the -FOG model up to a maximum of 1830 meters.
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.
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.
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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 (OSI), CAN partially defines the services for layer 1 (physical) and layer 2 (data link). Other standards such as DeviceNet, 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.
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 bitwise arbitration mechanism fails.
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.
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.
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 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 µs at 500 kbps.
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.
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.
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 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.
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.
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 each weekday (except holidays) between 8:00 a.m.
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, Customer 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.
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.
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.
Appendix A (continued) Permissible Cable Lengths and Nodes Per Segment Transceiver Description Cable Connectors -CXS -CXB coaxial star coaxial bus RG-62/u RG-62/u BNC BNC -FOG -FOG -FOG duplex fiber optic duplex fiber optic duplex fiber optic 50/125 62.5/125 100/140 ST ST ST 1 2 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.
(2.5 Mbps) Cable Length Min Max Max Nodes Bus Segment 0 2000 ft/610 m 6 ft/2 m1 1000 ft/305 m 0 0 02 N/A 8 3000 ft/915 m N/A 6000 ft/1825 m N/A 9000 ft/2740 m N/A TD960801-0MC 33 Notes 5.5 dB/1000 ft max 5.5 dB/1000 ft max 4.3 dB/km max 4.3 dB/km max 4.
Appendix B—Declaration of Conformity Applied Council Directives: Electromagnetic Compatibility Directive, 89/336/EEC Council Directive as amended by Council Directive 92/31/EEC & 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
Type of Equipment: Industrial network extender Model Directive EMC EB/DNET-CXB EB/DNET-FOG Yes Yes Technical File TD960801-0FA I, the undersigned, hereby declare that the product(s) specified above conforms to the listed directives and standards. George M.
