CAN in Automation (CiA) - Controller Area Network (CAN) CAN HLP Members only Map home CAN in Automation (CiA) international users and manufacturers group Founded in March 1992, CiA provides technical, product and CAN Information in marketing information with the aim of fostering Controller Area Dutch Network’s image and providing a path for future developments of the CAN protocol. The non-profit trade association with a persistently increasing number of members develops and supports various CAN-based higher layer protocols: CAN Application Layer (CAL), CAN Kingdom, CANopen, DeviceNet. Higher layer CAN the bus CiA members protocols (HLP) only - General introduction - General introduction - CiA specifications - Specifications - CANopen - Technical info - Controller - Devicenet - Marketing info - Applications - CAN Kingdom Events Standardization Products CiA phone +49-9131-69086-0 fax +49-9131-69086-79 Literature Download News email:[email protected] http://www.can-cia.de/ [14.11.1999 12:45:51] CAN in Automation Higher Layer Protocols HLP DeviceNet CANopen General introduction General introduction Technical introduction Technical introduction Specifications Specifications Conformance test Conformance test FAQs FAQs Vendor list CAN Application Layer CAN Kingdom General introduction General introduction Technical introduction Technical introduction Specifications Specifications © CAN in Automation last update: 1999-07-26 http://www.can-cia.de/hg.htm [14.11.1999 12:46:07] CAN in Automation General introduction DeviceNet Page contents: More: Features and functionality First information Technical introduction Features and functionality Specifications Conformance test Network Up to 64 nodes Size FAQs Network Selectable end-to-end network distance varies with speed Length Page contents: Top Baud Rate Distance Features and 125 Kbps 500 m (1,640 ft) functionality First information 250 Kbps 250 m (820 ft) 500 Kbps 100 m (328 ft) Data 0-8 bytes Packets Bus Linear (trunkline/dropline); power and signal on the same Topology network cable Bus Peer-to-Peer with Multi-Cast (one-to-many); Multi-Master and Addressing Master/Slave special case; polled or change-of-state (exception-based) More: System Removal and replacement of devices from the network under Features power Technical introduction Specifications First information Conformance test DeviceNet is a low-cost communications link to connect industrial FAQs devices (such as limit switches, photoelectric sensors, valve manifolds, motor starters, process sensors, bar code readers, variable frequency drives, panel displays and operator interfaces) to a network Page contents: and eliminate expensive hardwiring. Top The direct connectivity provides improved communication between Features and devices as well as important device-level diagnostics not easily functionality accessible or available through hardwired I/O interfaces. First information DeviceNet is a simple, networking solution that reduces the cost and time to wire and install industrial automation devices, while providing interchangeability of "like" components from multiple vendors. DeviceNet is an open network standard. The specification and http://www.can-cia.de/hdg.htm (1 von 2) [14.11.1999 12:46:16] CAN in Automation protocol are open; vendors are not required to purchase hardware, software or licensing rights to connect devices to a system. Anyone may obtain the DeviceNet Specification from the Open DeviceNet More: Vendor Association, Inc. (ODVA) for a nominal reproduction charge. Any company that manufactures (or intends to manufacture) Technical DeviceNet products may join ODVA and participate in technical introduction working groups that are developing enhancements to the DeviceNet Specifications Specification. Conformance test Buyers of the DeviceNet Specification receive an unlimited, FAQs royalty-free license to develop DeviceNet products. Companies looking for assistance may purchase sample code that eases their implementation, development toolkits, and development services from Page contents: many sources. The key hardware components are available from the largest worldwide suppliers of semiconductors. Top Features and Why the DeviceNet Communication Link? functionality First information For years the process industry has been attempting to develop a single, open standard to address all kinds of field devices. The original scope of their standards effort was aimed at replacing the 4-20 mA standard with a single digital standard. As the scope increased to address complex and sophisticated services (such as high data rate communications between controllers, time synchronization of large numbers of devices scanning at very high speeds), the development of a single standard became delayed. More: At the same time, the cost of communication technology has dropped considerably in recent years, making it cost-effective to connect simple Technical devices never considered for SP50 fieldbus directly to a network. Such introduction a standard for simple devices requires the same level of Specifications interchange-ability as exists for 120/220 VAC and 24 VDC discrete, hardwired I/O. DeviceNet allows the interchangeability of simple Conformance test devices while making interconnectivity of more complex devices FAQs possible. In addition to reading the state of discrete devices, DeviceNet provides the capability to report temperatures, to read the Page contents: load current in a motor starter, to change the deceleration rate of drives, or to count the number of packages that have passed on a conveyor in the previous hour. Top Features and © ODVA - The Open DeviceNet's Vendor Association functionality First information © CAN in Automation last update: 1999-07-27 http://www.can-cia.de/hdg.htm (2 von 2) [14.11.1999 12:46:16] CAN in Automation Technical introduction DeviceNet Page contents: More: Physical Layer and Media Indicators and Configuration Switches General introduction Communication Protocol and Application Specifications The Object Model Conformance test Messaging FAQs Predefined Master/Slave Connection Set Device Profiles Page contents: Physical Layer and Media Top Chapter 9, Volume 1 in the DeviceNet Specifications defines the Physical Layer and allowable Topologies and components. The variety of Topologies Media that are possible is shown in Figure 2. The specification also deals Indicators and with system grounding, mixing thick and thin media, termination, Configuaration Switches Communication Protocol and power distribution. and Application The basic trunkline-dropline Topology provides separate twisted pair The Object Model busses for both signal and power distribution. Thick or thin cable can Messaging be used for either trunklines or droplines. End-to-end network Predefined Master/Slave distance varies with data rate and cable size. Connection Set Device Profiles Data Rates 125 Kbps 250 Kbps 500 Kbps Thick Trunk Length 500 m 250 m 100 m (1,640 ft) (820 ft) (328 ft) Thin Trunk Length 100 m 100 m 100 m (328 ft) (328 ft) (328 ft) More: Maximum Drop Length 6 m 6 m 6 m (20 ft) (20 ft) (20 ft) General introduction Cumulative Drop Length 156 m 78 m 39 m Specifications (512 ft) (256 ft) (128 ft) Conformance test FAQs The end-to-end network distance varies with data rate and cable thickness. Devices can be powered directly from the bus and communicate with each other using the same cable. Nodes can be removed or inserted from the network without powering-down the network. Power taps can be added at any point the network, which makes redundant power supplies possible. The trunkline current rating is 8 amps. An opto-isolated design option allows externally powered http://www.can-cia.de/hdt.htm (1 von 15) [14.11.1999 12:47:01] CAN in Automation devices (e.g. AC Drives starters and solenoid valves) to share the Page contents: same bus cable. Other CAN-based networks allow only a single power supply (if at all) for the entire network. Top Physical Layer and Media Indicators and Configuaration Switches Communication Protocol and Application The Object Model Messaging Predefined Master/Slave Connection Set Device Profiles More: General introduction Specifications Conformance test FAQs Page contents: Top Physical Layer and Media Indicators and Configuaration Switches Communication Protocol and Application The Object Model Messaging Predefined Master/Slave Connection Set Device Profiles http://www.can-cia.de/hdt.htm (2 von 15) [14.11.1999 12:47:01] CAN in Automation More: General introduction Specifications Conformance test FAQs Page contents: Top Physical Layer and Media Indicators and Configuaration Switches Communication Protocol and Application The Object Model Messaging Predefined Master/Slave Connection Set A simplified block diagram of transceivers with both isolated and Device Profiles non-isolated physical layers is shown in figure 3 and figure 4. The DeviceNet Specifications contain additional information concerning component requirements, protection from mis-wiring, and examples. More: General introduction Specifications Conformance test FAQs Figure 5. Open and Sealed Connectors are available on DeviceNet Several different connector types can be used on DeviceNet (see figure 5). Both sealed and unsealed connectors are available. Large (mini-style) and small (micro-style) sizes of pluggable, sealed connectors are available. For products, which do not require sealed connectors, open-style connectors can be used. Screw or clamp connections can be made directly to the cable if a pluggable connection is not required. The DeviceNet Specification also http://www.can-cia.de/hdt.htm (3 von 15) [14.11.1999 12:47:01] CAN in Automation contains information on how to use these cable and connector Page contents: components to construct single and multi-port taps. Top Indicators and Configuration Switches Physical Layer and Media Although DeviceNet does not require a product to have indicators, if Indicators and a product does have indicators, it must adhere to the DeviceNet Configuaration Switches Specification. It is recommended that either a Module Status LED Communication Protocol and a Network Status LED, or the combined Module Status/Network and Application Status LED be included. The Object Model Messaging The indicator(s) consist of bi-color (green/red) LEDs, which can Predefined Master/Slave have combinations of on, off or flashing. The Module Status LED Connection Set indicates whether or not the device has power and is operating Device Profiles properly. The Network Status LED indicates the status of the communication link. Communication Protocol and Application More: Chapters 3, 4 and 5, Volume 1 of the DeviceNet Specification General introduction defines the DeviceNet Communication Protocol. These chapters deal Specifications with connections, messaging protocol, and the communications Conformance test related objects respectively. FAQs Applications using DeviceNet combine standard or application specific objects together into what is called a Device Profile. The Device Profile fully defines the device as viewed from the network. Page contents: A library of objects is contained in Chapter 6, Volume II of the DeviceNet Specifications. A library of Device Profiles is contained Top in Chapter 3, Volume II of the DeviceNet Specifications. ODVA Physical Layer and coordinates the work of industry experts in the development of both Media Indicators and new Object and Device Profile Specifications. This is done through Configuaration Switches Special Interest Groups (SIG). Communication Protocol DeviceNet supports strobed, polled, cyclic, change-of-state and and Application application-triggered data movement. The user can choose The Object Model master/slave, multi-master and peer-to-peer or a combination Messaging Predefined Master/Slave configuration depending on device capability and application Connection Set requirements. The choice of data movement can significantly speed Device Profiles up system response time. One popular application for DeviceNet is to use a standard, pre-defined set of connections, which allow devices to operate in a Master/Slave Connection Set. Connections The DeviceNet Communication Protocol is based on the idea of connections. You must establish a connection with a device in order to exchange information with it. http://www.can-cia.de/hdt.htm (4 von 15) [14.11.1999 12:47:01] CAN in Automation To establish a connection, each DeviceNet product will implement either an Unconnected Message Manager (UCMM) or an More: Unconnected Port. Both perform their function by reserving some of the available CAN identifiers. The UCMM is described in detail in General introduction Chapter 4, Volume 1 of the DeviceNet Specification, and the Specifications Unconnected Port is described in Chapter 7, Volume 1. Conformance test When either the UCMM or the Unconnected Port is used to establish FAQs an Explicit Messaging Connection, that connection is then used to move information from one node to the other, or to establish additional I/O Connections. Once connections have been established, Page contents: I/O data may be moved among devices on the network. At this point, all the protocol of the DeviceNet I/O message is contained within the Top 11-bit CAN identifier. Everything else is data. Physical Layer and Media The 11-bit CAN identifier is used to define the connection ID. Indicators and DeviceNet divides the 11-bit CAN identifier into four groups. The Configuaration Switches first three defined groups contain two fields, one 6-bit field for MAC Communication Protocol ID and the other for Message ID. The combined fields define the and Application connection ID. Figure 7 shows message groups definitions. Group The Object Model Messaging four messages are used for offline communications. Predefined Master/Slave Devices may be Clients or Servers or both. Clients and Servers may Connection Set be producers, consumers or both. In a typical Client device, its Device Profiles connection would produce requests and consume responses. In a typical Server device, its connections would consume requests and produce responses. DeviceNet provides for several variations on this model. Some connections in either a Client or a Server may only consume messages. These connections would be the destination for More: Cyclic or Change-of-State messages. Similarly, some connections in either a Client or Server may only produce messages. These General introduction connections would be the source for Cyclic or Change-of-State Specifications messages. The use of Cyclic and Change-of-State connections can Conformance test substantially reduce bandwidth requirements. FAQs By design, nodes in a DeviceNet system are responsible for managing their own identifiers. These identifiers are interleaved (distributed) throughout the entire range. All nodes have a full range of message priorities available to them regardless of their MAC ID. Through the duplicate MAC ID algorithm, the uniqueness of CAN identifiers is guaranteed without the need for a central tool or record for each network. A related issue is detection of duplicate nodes. Because DeviceNet uses a device address inside the CAN Identifier Field, it presents a mechanism for detecting duplicate addressed devices. Preventing duplicate addresses is better than trying to locate them after they occur - something not taken into account in other CAN-based http://www.can-cia.de/hdt.htm (5 von 15) [14.11.1999 12:47:01] CAN in Automation networks. Page contents: Another key benefit to nodes managing their identifiers is that a user Top can add and delete nodes and/or add additional peer-to-peer Physical Layer and messages among existing nodes at any time without having Media knowledge of the existing set-up. No centralized record must be Indicators and located or reconstructed. Since nodes know, which IDs are already in Configuaration Switches use, a tool simply has to request an I/O connection be added between Communication Protocol the two devices, specifying priority level, the data path (class, and Application instance, attribute) and the production trigger (cyclic, poll, or The Object Model change-of-state). Messaging Predefined Master/Slave Identifier Bits Hex Identity Connection Set Range Usage 10 9 8 7 6 5 4 3 2 1 0 Device Profiles Group 1 Source MAC ID 000 - Message 0 Message ID 3ff Group 1 Group 2 400 - Message More: 1 0 MAC ID Message 5ff Group 2 ID General introduction Group 3 Specifications Source MAC ID 600 - Message 1 1 Message 7bf Group 3 Conformance test ID FAQs Group 4 Message 7c0 - Message 1 1 1 1 1 ID 7ef Group 4 (0 - 2f) Page contents: Invalid 7f0 - Top 1 1 1 1 1 1 1 X X X X CAN 7ff Physical Layer and Identifiers Media Indicators and 10 9 8 7 6 5 4 4 3 2 1 0 Configuaration Switches Communication Protocol and Application Figure 7 DeviceNet has 4 defined groups The Object Model Messaging Predefined Master/Slave The Object Model Connection Set Device Profiles The Object Model provides a template for organizing and implementing the Attributes (data), Services (methods or procedures) and Behaviors of the components of a DeviceNet product (see figure 8). The model provides an addressing scheme for each attribute consisting of four numbers. They are the Node Address (MAC ID), the Object Class Identifier, the Instance Number, and the Attribute Number. This four-level address is used in conjuction with an Explicit Messaging Connection to move data from one place to http://www.can-cia.de/hdt.htm (6 von 15) [14.11.1999 12:47:02]