CANopen lifts people

Quelle: CAN Newsletter 1/2004 (www.can-cia.org/newsletter) By Holger Zeltwanger, CAN in Automation

Specification

Doors are closing. The synthetic voice in the lift becomes silent. The electronic devices controlling the lift start to communicate inaudibly for human beings before the lift moves the passenger to the requested floors. In the past, the embedded lift control system used proprietary networks and device interfaces. This lead either to high efforts in system integration or the lift manufacturer had to buy all electronic devices from one single manufacturer.

In the near future, lift control systems may be based on the CANopen Lift application profile. It was officially introduced at the Interlift exhibition in Augsburg (Germany) on the joint booth of the non-profit CAN in Automation (CiA) international users’ and manufacturers’ group. CiA’s CANopen Special Interest Group (SIG) Lift has developed the specification, which describes the communication in multiple lift control system. It is the first time that different vendors have jointly developed an embedded lift communication system. The exhibiting companies showed prototypes of panels, drives, doors, controllers, etc. compliant to the CANopen Lift standard. Besides the prototype lift control system at the CiA booth, several CiA member companies exhibited CANopen Lift products at their own booths. Böhnke + Partner (www.boehnkepartner.de) exhibited another CANopen multivendor lift application based on their lift controller and a CANopen-compatible drive by Control Techniques. The demonstrated bp306 lift controller with two CANopen interfaces is configurable via the CANwizard tool that can also be used for any other CANopen Lift-compliant device. Additional interfaces included ISDN, modem and Ethernet. The company also presented the CAP-01 board to be used in external and internal panels, and the CLK-01 cabin controller.

Weber Lifttechnik (www.weber-lifttechnik.de) introduced the weCAN lift control controller featuring 60 landings and group control capability (up to lifts). The controller is compliant to the CANopen Lift application profile. The company also offered plain text menu-driven displays.

The CANopen Lift specification (DSP 417) is available at the CiA office in Germany (www.can-cia.org). The specification describes the default communication of a control system for up to eight lifts with up to 254 floors each. The default communication can be changed by means of configuration. The CANopen Lift specification does not standardize physical devices. The specification defines “virtual devices”. They are, in a manner of speaking, the atomic granularity of functions to be implemented in the same physical device. A virtual device must not be distributed to several physical devices. However, it is possible to combine several virtual devices in one physical device. This concept supports the description of transparent gateways. This means the design of the network topology is not predicted. The lift system designer is not restricted by the specification regarding the layout of networks.

Device

Panels, displays, and encoders

A lift control system is made of very different parts including electronic devices that measure, control and actuate. The communication between the electronic control devices is done silently and invisible for passengers. They only see some displays indicating in which floor the lift is at the very moment or push buttons to call the lift car. The CANopen lift profile defines control devices (call controller car door controller, car drive controller, etc.), as well as virtual devices, such as output and input panel, car door unit, car position unit, car drive unit, load measuring unit, etc.

SCHAEFER GmbH (www.ws-schaefer.de) has developed a broad range of CAN-con-nectable tableaus. Via the CiA DSP 417-compliant gateway the tableau subsystem can easily be integrated in a CANopen-based lift control system. Kronenberg (www.kronenberg-gmbh.de) has launched lift-operating panels for landing stations as well as for lift cars. They are compliant to CiA DSP 417. The first car position devices compliant to the CANopen lift profile based on standard encoders were introduced by Fraba (www.posital.com) and IVO (www.ivo.de). Schmersal (www.schmersal.com) has chosen a different technology: The USP elevator positioning system is a non-con­tact sensor for positioning measurements of up to 130 m. The DSP-based sensor supports the CANopen Lift profile. At the Interlift exhibition, several companies launched car drive units (frequency converters) compliant to CiA DSP 417. The frequency inverters are functionally compatible to standard CANopen drives, optionally they may support additional functions such as jerk control. The Micovert 2000 frequency converter from Micotrol (www.micotrol.com) supports open- and closed-loop control functions as well as six driving speeds. The 5-Star (DSV 5445 Lift) frequency converter from Dietz Electronic features a maximum of 132 kW lifting power. The car drive unit provides speed, position, and torque control in all quadrants. Siemens (www.siemens.de/edm) has developed a CANopen DSP 417 gateway for its lift car door unit. The AT-series drives doors up to 400 kg. The AT 25 lift door unit and the corresponding CANopen gateway can easily be connected to any CANopen DSP 417 door controller. These modules were used in the CiA prototype application. The lift builder benefits from standardized device-interfaces. System design needs much less effort when using standardized communication networks. In addition, the lift builder can integrate more easily devices from third parties. Another benefit is the availability of off-the-shelf configuration and maintenance tools. Device manufacturers benefit from the reduction of variants they have to provide in order to supply several lift builders. The lift car decelerates unnoticeably. The soft voice says: “Doors are opening”. In order to educate interested lift builders as well as device manufacturers, CiA is going to organize a seminar dedicated on the CANopen Lift application profile in Spring 2004. In order to make developers’ work as easy as possible, Böhnke + Partner has introduced the CANopen starter kit for developers of CANopen lift devices.