CAN Newsletter December 2007
| Business | New and updated CiA specifications - Business Esd company profile - FPGA with CAN Automotive architecture: less units, new functions |
|---|---|
| Application | CANopen drives improve handling and packaging Customized packaging via CAN plotter Print shop delivery machine uses CANopen Profit from sun energy with CAN technology CANopen in wind power turbines Managing design intricacies of forklifts Three-wheeler scooter uses CAN Protection system for pedestrians |
| Device | Servo drives Components Cables - PC Interface card Programmable 3-kW power supply for labs and test J1939 mobile hydraulic power generator Digital signal processing with Bessel low-pass filter FPGA-based controller card Controller boards and PLCs Sensors and dataloggers Human machine interfaces HMI - Pressure sensor - Display Gateways and Interfaces |
| Semiconductor | Gateway requirements: CAN meets FlexRay Micro-controller with CAN and FlexRay Automotive micro-controllers CiA 447 tool - IEC 61131-3 run-time system FPGA tool - Automotive CAN blockset - Tool chain |
| Tools | Scheduling analysis for CAN and FlexRay Automotive and industrial automation tools Tire pressure tool - Prototyping and developing tool |
| Software | Protocol stacks and software - Autosar stack |
| Reader service | CAN Newsletter subscription form |
Profit from sun energy with CAN technology
- Fig. 1: Conergy uses CANopen to network inverters, monitoring systems, PLCs, and tracking systems, which move the panels and one or more weather stations
By Jan Hansen (Conergy)
To produce electricity from sunlight requires more than just a solar generator. Electronic components are necessary to bundle the power of different strings of solar modules, to condition the eco-friendly power for feeding it into the public power grid and to monitor the whole photovoltaic system. Conergy – one of the leading providers of products and systems in the area of renewable energies – uses CAN technology to link these electronic devices.
Each photovoltaic system - irrespective of size - consists of certain components:
- A solar generator to produce DC current.
- A junction box containing safety features and monitoring components, e.g. Conergy SmartConnect.
- An inverter to convert DC into AC current and to feed it into the public power grid, e.g. Conergy IPG.
- A monitoring system to inform the operator about yields and failures, e.g. Conergy SunReader or SmartControl.
- In recent years, yet another kind of devices has been established for large solar parks: tracking systems. As with the Conergy SolarOptimus, these systems optimally orient the modules towards the incoming radiation. In this way, the energy yield can be significantly maximized.
The company provides photovoltaic components for different kinds of applications: small and medium-sized photovoltaic systems for private houses or small commercial applications on the one hand, and large photovoltaic power plants as capital goods on the other hand.
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CANopen in wind power turbines
- Fig. 1: An Enercon windmill is being assembled
Heribert Einwag (Moeller)
Enercon develops and produces gearless wind power turbines that are a benchmark for the market in terms of power, reliability and lifespan. Research and development at Enercon determine the level of innovation. The company’s slogan indicates its primary motivation: energy for the world. Enercon chose Moeller’s (www.moeller.net) XC100-FC modular PLC with a fiber-optic CANopen interface for controlling and monitoring the aviation beacon system. The company’s wind turbines are equipped with state-of-the-art microelectronic control technology developed in-house. The main processing unit, which is the central element of the control system, is in continuous contact with the peripheral control elements, such as the yaw control and active pitch control system. Its function is to adjust the individual system parameters to ensure the wind turbines operate at optimum yield under all weather conditions.
The correct feeding of electricity from the wind turbine into the grid requires the monitoring of the grid connection. Grid parameters such as voltage, current and frequency are measured on the low-voltage side between the turbine inverter and the system transformer. All measured values are continuously transmitted to the system control, enabling the turbine to react immediately to changes in the grid voltage or frequency. As soon as the defined limit values of the system protection are exceeded, the wind turbine is safely shut down and service staff is informed. When the voltage and frequency return to within the permissible tolerances, the wind turbine is automatically started up again, thus preventing lengthy downtimes.
The Enercon control system ensures a yield-optimized turbine operation under all weather conditions. The engine nacelle is therefore provided with adaptive yaw control for which measurement data from the wind sensor is evaluated constantly. A variable speed control is provided for optimum wind turbine efficiency at every wind strength. It eliminates any undesirable output peaks or high operating loads. The active pitch control system enables the ideal flow angle to be set at the rotor blades to ensure maximum yields and load reductions for the entire wind turbine. The Enercon brake system ensures maximum turbine reliability by means of three independently operating pitch mechanisms with standby power supply if the grid supply fails. Tower and generators are monitored by means of vibration and acceleration sensors to check the deflections in the tower. Temperature and air gap sensors measure other control parameters.
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Devices
Servo actuates steppers
Octacom has released the SMS servo drives with CANopen interface. The drives provide an innovative function that enables them to actuate stepper motors from the energy-optimized servo mode. Thus stepper motors can be run as highly dynamic and efficient torque motors. They can be run with the motor’s own maximum torque and cycle times are thus reduced by up to 30%. Digital signal processors in the device are responsible for power, torque and position control. Communication interfaces include CANopen and RS-232 via which the parameter setting and programming is done. The company provides the System Designer Tool with the drive.
Frequency inverter series
Nord provides the Nordac SK 500E/520E/530E frequency inverters with CANopen interface. The devices performance ranges between 0,25 kW and 7,5 kW. Integrated monitoring functions for input voltage, output current and motor temperature, an integrated line filter and a brake management system ensure reliable operation of the device. Default features include sensorless current vector control (ISD), PIC and process controllers, a brake chopper and a line filter. The 530E features a Safety Stop function according to EN 954-1 category 3. The actuators are also available with DeviceNet interface optionally.
Minidrive with CAN
Technosoft has added the ISP210 minidrive with CAN interface to its family of drives with computing power. The device has been designed to embed motion control, drive and PLC functionalities in 62 mm x 42 mm x 20 mm space. The board control DC and stepper motors up to 2 x 12 W (24 V, 0,5 A) in open- or closed-loop modes. The company has also added the PIM2403 plug-in servo drive with computing power. The PIM2403 provides a CAN interface with CANopen protocol, as well as an RS-232 interface. The board can be plugged onto a printed circuit board (PCB) without any cables. The drive control DC, brushless, linear, and step motors up to 75 W (24 V, 3 A) and embeds motion control, drive and PLC functions on a board measuring 59 mm x 42 mm x 20 mm.
With CAN systembus
For low-rating motors of up to 240 W, Jetter has developed the motion controller JetMove 105 with CAN-based systembus and computing power. Its measures 136 mm x 85 mm x 26 mm. The smallest motor that can be driven by the device has got a torque of 0,003 Nm and a flange size of 25 mm. As all other JetControl devices, they are programmed and commissioned by means of the programming software and language of the controller. All common motor types can be driven by the motion controller: servo motors, stepper motors, asynchronous motors, and linear drives.
With CANopen or DeviceNet
ABB has released ACSM1 drive with a power range from 0,75 kW to 22 kW (380 V to 480 V) and CANopen or DeviceNet interface. The device provides servo level control performance, ranging from open-loop speed and torque control for standard induction motors to closed-loop position/synchronization, speed and torque control for synchronous servo motors. It features a supporting incremental encoder, resolver and multi-turn absolute encoder feedbacks. For open-loop standard induction motor applications, the ACSM1 offers an control dynamics limited by motor type not by the drive, and function block programmability (IEC 61131-3 function block diagrams) as default, amongst others. For closed -loop synchronous servo (or asynchronous) motor applications, the device also provides position control/synchronization functionality and support for several position feedback devices.
Complies to CiA 402
Unipos drives by Föhrenbach provide a CANopen CiA 402 interface as well as USB, EtherCat, etc. Internally they provide connection for five (C110), and nine (C220) axes for either servo or stepper motors. External axes may be connected to the modular control concept of the drive via the interfaces. Digital I/Os enable communication with peripheral sub-layered devices and super-layered controllers.
For lift applications
Fuji provides the Frenic Lift frequency inverters with CANopen interface for lift applications. The power range spans from 5,5 kW to 30 kW. The lift inverter can drive asynchronous motors with and without encoders and permanent magnet asynchronous motors, says the company. The company built in encoder input and braking resistor. Interfaces such as RS-485, Modbus, and CANopen are included by default.
Implements CiA 414
The CANstepper by Klöcker is a mechatronical actuator that consists of a rotary drive unit with computing power and with built-in complex electronics including CAN. The drive is suitable for applications in the textile industry, where lightweight fibers and needles have to be moved at high speeds under environmental conditions, such as vibrations, dust and 24 hours/7days-operation. A special application, for example, is its usage as a leno device on weaving machines for selvedge binding of the woven fabric implemented according to CiA 414.
Motion system
Kuhnke provides the Fuxx Pilot as central unit in its motion concept. The real-time IPC communications with the Fuxx Control and the Fuxx Drive via CANopen. The motion software uses the CoDeSys environment and supports users with motion control libraries and diagnostic programs, etc. The drives are available in different sizes and with different torques ranging from 0,05 Nm to 120 Nm and with powers from 25 W to 50 W.
Safety platform
The decentralized PSSuniversal control platform by Pilz can also communicate exclusively via CANopen or DeviceNet. Whereas the controller used to be able to run in a combination of SafetyBus p and CANopen or DeviceNet only, it can do so solely via the latter protocols now. Analog and digital I/Os can be connected without any functional connection to the safety technology of the controller.
Managing design intricacies of forklifts
By Heinz-Jürgen Oertel (Port) and Monika Mack (CiA)
Modern forklifts use a variety of electronic devices. These devices are networked via one or more CAN networks, quite often with the CANopen higher-layer protocol. The company Jungheinrich manufactures a variety of pallet trucks, forklifts, and order stackers that use CANopen networks. With over 40 different vehicles, system design has become a highly complex matter. Jungheinrich uses a sophisticated CANopen design tool for this in combination with an approach that enables to deduce individual systems and device descriptions from a CANopen “global object dictionary”.
Jungheinrich develops some of the electronic devices for the forklifts in-house, but also outsources developments to third parties. The one thing that always is always developed in-house and remains the company’s know-how, however, is the design of the vehicle system. This includes the development of the device specifications, even though the company may not manufacture the actual parts themselves.
To ensure fast development cycles even with the number of different vehicle types, the company uses a holistic approach, from which the vehicle systems and the individual device descriptions can be derived. The CANopen object dictionary (OD) plays a major part in this approach: The company developed a “global object dictionary”, which contains all objects in the company-specific area of the OD that are required to run and service Jungheinrich forklifts. The idea behind this approach was to divide the total amount of objects into sub-segments in such a way as to enable a vehicle system designer to generate all object dictionaries of all devices within the system by simply importing segments from the “global object dictionary”. For example: A system designer could have the task of designing the communication structure of a vehicle, which uses:
- Master controller
- AC drive of the power train
- AC drive of the lift motor
- Inputs and outputs for the interfacing devices
The “global object dictionary” contains a sub-segment for the basis functions of all CANopen participants in Jungheinrich vehicles. This contains e.g. objects for the system time, for log entries, for default settings of the service parameters, for the execution of the system self tests, etc. This sub-segments “standard objects” is the first to be imported into the device-specific objects dictionary. Then follow the specific sub-segments for the device object dictionaries, which describe the device functionalities.
For AC drives, this may be objects for the revolution speed nominal values and actual values, for the description of the motor equivalent circuit diagram, for the settings of the encoders, for status messages concerning the output stage, etc.
It is possible to combine several sub-segments within a single device because of the fixed, non-overlapping sub-segment areas within the “global object dictionary”. This could be the case, e.g. for the drive control with interface functionality. At the end of the design process, the system designer defines the communication parameters for the process and service data communication. Thus, in a short time, all communication profiles are developed, whether for Jungheinrich’s own device manufacturing or as specification basis for third party developments.
This whole process is unthinkable without a sophisticated software tool. If it was done, e.g. on a C source code basis, all participants in the development process including third party suppliers would have to use the very same protocol stack. Logistically this is not feasible.
For several of their projects, Jungheinrich has been using the CANopen protocol stack by the company Port. Along with the software stack comes the company’s CANopen Design Tool. With this tool it is possible to assemble an object dictionary from the CiA CANopen device profiles. Jungheinrich uses the tool to assemble its “global object dictionary” as reference for all device object dictionaries used with in a project.
To create and administrate the individual device profile the tool extension CAN-Merge is a suitable option. This tool contains functions to compare and mix projects done in the CANopen Design Tool. Rüdiger Schwarz, Head of Software Development at Jungheinrich, said: “The CANopen Design Tool and the CAN-Merge extension tool were highly suitable to create our global object dictionary. The tools met all our requirements and enabled us to coordinate the different CANopen projects in the forklifts in a comfortably and time-saving fashion.”
Since the tool outputs the electronic data sheet (EDS) files into the standardized XML format (see CiA 411), further processing into reports is possible with XSL style templates via commonly available XML tools. The design tool also supports the version management in e.g. CVS or Subversion format. Version management is not just useful, but an essential requirement in projects that are subject to rigorous quality checks, such as forklifts.
