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TURCK CANopen Specifications

TURCK 6/5/2018
What is it?
CANopen is a communication protocol and device profile specification for embedded systems in automation applications.
What are its basic components?
Controller, power supply, CAN cable, CANopen I/O nodes and terminating resistors
Where is it used?
Industrial automation, mobile equipment, transportation, medical, military and building automation
Who is responsible for it?
CAN in Automation (CiA), the international users’ and manufacturers’ organization, develops and supports CAN-based higher-layer protocols
CANopen is a higher layer open protocol implemented using the CAN (controller area network) lower level protocol.
The CANopen standards, as defined by the CiA (CAN in Automation) organization, are split between communication profiles and device profiles. Communication profiles define the various communication mechanisms and objects used within the CANopen environment. Device profiles provide specific requirements for similar device types from different manufacturers to ensure that the implementation of those devices remains consistent.
CANopen utilizes an object based structure. Each node stores I/O and parameter data within index locations mapped in the device’s OD (object dictionary), as defined by the device profile. These objects can be accessed via SDO (Service Data Object) or PDO (Process Data Object) messages.
Service Data Object (SDO)
SDO messages are primarily used for node configuration and parameterization. Point-to-point SDO messaging allows access to a single entry in the object dictionary and consists of both a request and response message.
Process Data Object (PDO)
PDO messages are used to transmit process I/O data. These non-confirmed messages can be configured to transmit multiple data objects, up to 8 bytes, within a single message. Communication modes available for PDO transmission include:
•  Event Controlled: The PDO transmission is triggered by COS (Change of State) of data contained within the objects mapped into the PDO
•  Time Driven: The PDO is generated on a fixed time interval
•  Request Controlled: Polled PDO transmission occurs in response to a remote request frame from a master or another node
•  Cyclic Synchronized: Nodes apply output data received and store input data (to be sent as the bus becomes available) upon transmission of a SYNC message. Often used in motion applications, this mode allows process data to be triggered and/or collected from multiple nodes at a single moment in time.
The NMT (Network Management) master uses NMT messages to control the operational state of each node (e.g. pre-operational, operational, reset). Heartbeat and node guarding are also functions of NMT messaging. Data rates available for CANopen include 1Mbit, 800kbps, 500kbps, 250kbps, 125kbps, 50kbps, 20kbps and 10kbps. A maximum of 127 devices are possible on a typical CANopen network (11-bit CAN message identifiers).
Basic Parts List:
A typical system consists of the following basic components:
•  Controller
•  Power Supply
•  CAN Cable
•  CANopen I/O Nodes
•  Terminating Resistors
Physical Requirements and Maximums
CANopen is implemented based off the trunk and drop topology. It is recommended that a cable be used with 120Ω characteristic impedance. Both ends of the trunk are to be properly terminated with a resistance representing the characteristic impedance of the transmission line (120Ω).
Bit Rate Bus Length Max Drop Length Accumulated Drop Length
1 Mbit/s 25 m 1.5 m 7.5 m
800 kbit/s 50 m 2.5 m 12.5 m
500 kbit/s 100 m 5.5 m 27.5 m
250 kbit/s 250 m 11 m 55 m
125 kbit/s 500 m 22 m 110 m
50 kbit/s 1000 m 55 m 275 m
20 kbit/s 2500 m 137.5 m 687.5
Communication Signal
CANopen signals conform to the Controller Area Network (CAN) standard as defined by ISO 11898. The signal type is a differential square wave, allowing for common mode noiserejection.
Oscilloscope capture of the differential CAN signal.The CAN high and low components are shown with the resulting difference below.
Although the CANopen specification requires cables to only contain CAN High, CAN Low and a CAN ground conductor, it is also acceptable to include a shield, V+ and V- (device power). The addition of device power bundled within the CAN cable becomes particularly useful within industrial automation as it saves both the added complexity and cost of running separate cables for CAN and device power. TURCK CANopen cables include the required signal conductors, as well as the shield and power pair, with V- also used as the CAN ground.
There are many different standardized connectors specified for CANopen (as defined in CiA DR 3031). TURCK offers cordsets with minifast® (7/8-16 UN), eurofast® (M12) and open style options. Cables are available in different physical sizes for more flexibility (thin cable) or longer trunk lengths (thick cable). Cordsets are available in standard lengths, but can also be customized through our sales representatives.