Optional parameters for CANopen provide additional support

CANopen features mandatory, conditional, and optional parameters. However, the device still has to behave as specified even if the optional parameters aren’t implemented to ensure interoperability.

05/21/2016


CANopen features mandatory, conditional, and optional parameters. However, the device still has to behave as specified even if the optional parameters aren't implemented.

CANopen features mandatory, conditional, and optional parameters for application layers. The mandatory parameters specified in the CiA 301 application layer have to be implemented. Some parameters are conditional. For example, if the user implements process data object (PDO) communication parameters the corresponding PDO mapping parameters also have to be provided. Optional functioning parameters also may be supported if they follow the specification. Optional parameters in CANopen devices, applications, and interface profiles follow the same interpretation. 

Check default value attribute

If the default value attribute is "none" or "manufacturer-specific," the device behaves as the user wants. If this attribute has a specified value, the product needs to follow this specification. For example, the error behavior parameter (index 1029h) is an array-type object that specifies the local NMT finite state automaton (FSA) transitions in case of severe errors, and it is optional.

Sub-index 1 (communication error) is another optional parameter that specifies a default value of "00h" (data type: Unsigned8). This means that the device must transit into NMT pre-operational state when the severe error occurs. Severe errors include heartbeat events or bus-off conditions of the CAN controller. If this object is not implemented, the device must behave as specified: It shall transit into the specified NMT state. The system designer can configure another behavior only when it is implemented.

In CiA 401, which is a CANopen device profile for generic input/output (I/O) modules, the "polarity digital input 8-bit" parameter (index 6002h) is optional. The default value is specified as 00h meaning inputs are not inverted. This means it is not allowed to provide an input inversion function if this object is not implemented. In the case of CiA 401, this is also clearly described in the profile specification: "If an optional parameter is not implemented, the device shall behave as specified in the default value attribute." 

Mandatory, if not implemented

Other profile specifications don't mention this explicitly. Nevertheless, optional parameters with dedicated default values determine the device's behavior. For example, CiA 402 (CANopen device profile for drives and motion control) specifies for the "quick stop option code" parameter (index 605Ah), which has a default value of "+2" meaning "slow down on quick stop ramp and transit into switch-on-disabled." This behavior is mandatory, even if the parameter is not implemented. It is not allowed to behave differently.

CANopen devices must behave as specified in the default value after power-on, and any optional parameters must follow suit. Optional does not mean your device may behave any way. Optional parameters are not allowed to implement a congruent functionality using manufacturer-specific parameters. This would decrease the interoperability of CANopen devices as a result.

Holger Zeltwanger is managing director, CAN in Automation (CiA). CAN in Automation is a CFE Media content partner. Edited by Chris Vavra, production editor, Control Engineering, CFE Media, cvavra@cfemedia.com.

ONLINE extra

See additional stories from CAN in Automation linked below.



Engineers' Choice Awards
The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by Control Engineering subscribers.
System Integrator Giants
The System Integrator Giants program lists the top 100 system integrators among companies listed in CFE Media's Global System Integrator Database.
System Integrator of the Year
Each year, a panel of Control Engineering and Plant Engineering editors and industry expert judges select the System Integrator of the Year Award winners in three categories.
How to Maximize Factory Automation Efficiency with Low Cost Machine Vision
This eGuide illustrates solutions, applications and benefits of machine vision systems.
Wireless Reliability in Harsh Environments
Learn how to increase device reliability in harsh environments and decrease unplanned system downtime.
Human Factors and the Impact on Plant Safety
This eGuide contains a series of articles and videos that considers theoretical and practical; immediate needs and a look into the future.
June 2018
Discrete and process sensor fundamentals, autotuning controls, system integrator roundtable
May 2018
Salary and Career Survey, IT and OT convergence, robotic standards and safety, secure circuit protection
April 2018
Cybersecurity best practices, artificial intelligence, robotic additive manufacturing, embedded systems, IIoT integration, energy efficiency
Edge Computing
This article collection contains several articles on how today's technologies heap benefits onto an edge-computing architecture such as faster computing, better networking, more memory, smarter analytics, cloud-based intelligence, and lower costs.
IIoT: Machines, Equipment, & Asset Management
Articles in this digital report highlight technologies that enable Industrial Internet of Things, IIoT-related products and strategies.
PLCs
Programmable logic controllers (PLCs) represent the logic (decision) part of the control loop of sense, decide, and actuate. Featured articles in this digital report compare PLCs and programmable automation controllers (PACs), industrial PCs, and robotic controllers.
SIDB

Find and connect with the most suitable service provider for your unique application. Start searching the Global System Integrator Database Now!

June 2018
Machine learning, produced water benefits, progressive cavity pumps
April 2018
ROVs, rigs, and the real time; wellsite valve manifolds; AI on a chip; analytics use for pipelines
February 2018
Focus on power systems, process safety, electrical and power systems, edge computing in the oil & gas industry
John O. Ayuk, PE, CFSE, PMP, CAP
Automation Engineer; Wood Group
Doug Baker
System Integrator; Cross Integrated Systems Group
Jose S. Vasquez, Jr.
Jose S. Vasquez, Jr.
Fire & Life Safety Engineer; Technip USA Inc.
Data Centers: Impacts of Climate and Cooling Technology
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
Safety First: Arc Flash 101
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
Critical Power: Hospital Electrical Systems
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
Engineers' Choice Awards
The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by Control Engineering subscribers.
System Integrator Giants
The System Integrator Giants program lists the top 100 system integrators among companies listed in CFE Media's Global System Integrator Database.
System Integrator of the Year
Each year, a panel of Control Engineering and Plant Engineering editors and industry expert judges select the System Integrator of the Year Award winners in three categories.
How to Maximize Factory Automation Efficiency with Low Cost Machine Vision
This eGuide illustrates solutions, applications and benefits of machine vision systems.
Wireless Reliability in Harsh Environments
Learn how to increase device reliability in harsh environments and decrease unplanned system downtime.
Human Factors and the Impact on Plant Safety
This eGuide contains a series of articles and videos that considers theoretical and practical; immediate needs and a look into the future.
June 2018
Discrete and process sensor fundamentals, autotuning controls, system integrator roundtable
May 2018
Salary and Career Survey, IT and OT convergence, robotic standards and safety, secure circuit protection
April 2018
Cybersecurity best practices, artificial intelligence, robotic additive manufacturing, embedded systems, IIoT integration, energy efficiency
Edge Computing
This article collection contains several articles on how today's technologies heap benefits onto an edge-computing architecture such as faster computing, better networking, more memory, smarter analytics, cloud-based intelligence, and lower costs.
IIoT: Machines, Equipment, & Asset Management
Articles in this digital report highlight technologies that enable Industrial Internet of Things, IIoT-related products and strategies.
PLCs
Programmable logic controllers (PLCs) represent the logic (decision) part of the control loop of sense, decide, and actuate. Featured articles in this digital report compare PLCs and programmable automation controllers (PACs), industrial PCs, and robotic controllers.
SIDB

Find and connect with the most suitable service provider for your unique application. Start searching the Global System Integrator Database Now!

June 2018
Machine learning, produced water benefits, progressive cavity pumps
April 2018
ROVs, rigs, and the real time; wellsite valve manifolds; AI on a chip; analytics use for pipelines
February 2018
Focus on power systems, process safety, electrical and power systems, edge computing in the oil & gas industry
John O. Ayuk, PE, CFSE, PMP, CAP
Automation Engineer; Wood Group
Doug Baker
System Integrator; Cross Integrated Systems Group
Jose S. Vasquez, Jr.
Jose S. Vasquez, Jr.
Fire & Life Safety Engineer; Technip USA Inc.
Data Centers: Impacts of Climate and Cooling Technology
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
Safety First: Arc Flash 101
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
Critical Power: Hospital Electrical Systems
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
Engineers' Choice Awards
The Engineers' Choice Awards highlight some of the best new control, instrumentation and automation products as chosen by Control Engineering subscribers.
System Integrator Giants
The System Integrator Giants program lists the top 100 system integrators among companies listed in CFE Media's Global System Integrator Database.
System Integrator of the Year
Each year, a panel of Control Engineering and Plant Engineering editors and industry expert judges select the System Integrator of the Year Award winners in three categories.
How to Maximize Factory Automation Efficiency with Low Cost Machine Vision
This eGuide illustrates solutions, applications and benefits of machine vision systems.
Wireless Reliability in Harsh Environments
Learn how to increase device reliability in harsh environments and decrease unplanned system downtime.
Human Factors and the Impact on Plant Safety
This eGuide contains a series of articles and videos that considers theoretical and practical; immediate needs and a look into the future.
June 2018
Discrete and process sensor fundamentals, autotuning controls, system integrator roundtable
May 2018
Salary and Career Survey, IT and OT convergence, robotic standards and safety, secure circuit protection
April 2018
Cybersecurity best practices, artificial intelligence, robotic additive manufacturing, embedded systems, IIoT integration, energy efficiency
Edge Computing
This article collection contains several articles on how today's technologies heap benefits onto an edge-computing architecture such as faster computing, better networking, more memory, smarter analytics, cloud-based intelligence, and lower costs.
IIoT: Machines, Equipment, & Asset Management
Articles in this digital report highlight technologies that enable Industrial Internet of Things, IIoT-related products and strategies.
PLCs
Programmable logic controllers (PLCs) represent the logic (decision) part of the control loop of sense, decide, and actuate. Featured articles in this digital report compare PLCs and programmable automation controllers (PACs), industrial PCs, and robotic controllers.
SIDB

Find and connect with the most suitable service provider for your unique application. Start searching the Global System Integrator Database Now!

June 2018
Machine learning, produced water benefits, progressive cavity pumps
April 2018
ROVs, rigs, and the real time; wellsite valve manifolds; AI on a chip; analytics use for pipelines
February 2018
Focus on power systems, process safety, electrical and power systems, edge computing in the oil & gas industry
John O. Ayuk, PE, CFSE, PMP, CAP
Automation Engineer; Wood Group
Doug Baker
System Integrator; Cross Integrated Systems Group
Jose S. Vasquez, Jr.
Jose S. Vasquez, Jr.
Fire & Life Safety Engineer; Technip USA Inc.
Data Centers: Impacts of Climate and Cooling Technology
This course focuses on climate analysis, appropriateness of cooling system selection, and combining cooling systems.
Safety First: Arc Flash 101
This course will help identify and reveal electrical hazards and identify the solutions to implementing and maintaining a safe work environment.
Critical Power: Hospital Electrical Systems
This course explains how maintaining power and communication systems through emergency power-generation systems is critical.
click me