Profidrive & Co nicely integrated
11 March 2010
The new Anybus-CC communication modules with integrated drive profiles incorporate Profidrive, CIP-AC/DC, CANopen DSP 402 and CC-Link as integrated software functions.
Anybus modules are plug-and-play interface modules for automation equipment. They include all the functions of a high-performance communication interface and are available for industrial Ethernet systems (Profinet, EtherNet/IP and Modbus TCP) and all major field busses, as well as serial interfaces, USB, and wireless networks. The mechanical design and the host hardware and software interfaces of the modules are standardised, which makes them interchangeable. Device manufacturers only need to integrate a single Anybus slot in their automation equipment in order to utilise the full spectrum of available module variants and thereby create the possibility of connecting to all major industrial networks with a single development step.
As an extension to its standard communication modules, HMS now offers a new module generation with software functions incorporating drive profile functions. The Anybus-CC drive profile modules and the standard modules have the same hardware and software interfaces on the host side, which means that the new profile modules can be installed in any existing Anybus-CC slot. In order to use the profile functions, the equipment manufacturer only has to implement the additional functions in the internal software of the drive.
Why drive profiles?
Drive profiles standardise device functions and address much more than simply specifying data exchange mechanisms. Profiles are defined by working groups of related industry associations, such as PNO, ODVA, and so on. Drives with integrated drive profiles provide significant added value for their users. Profiles enhance the ability of the drives to exchange data with each other by specifying the meaning and coding of the data (such as setpoint and actual values) as well as the configuration parameters of the drives (upper and lower limits, start and stop functions) in a uniform and manufacturer-independent manner. This enables users to employ the same software routines in PLCs regardless of the particular drive unit that is used, thereby dramatically reducing their engineering effort and expenditure.
Uniform yet different
You might normally expect that there would be only one profile for electric drives, but this is by no means true. As usual in the industrial communication world, a variety of profile definitions tailored to specific communication systems have become established in the market. For example, the Profidrive profile is used with Profibus and Profinet, the AC/DC profile is used with the CIP network family (ControlNet, DeviceNet and EtherNet/IP), and the DSP-402 pro-file is now used in networks based on CANopen, EtherCAT or Powerlink. A common feature of all profiles is that the nature, scope and coding of the drive-specific data and parameters are unambiguously specified in each profile. Unfortunately, the various industrial associations have not been able to agree on uniform definitions. As a result, the profiles differ fundamentally in how they address and code data and parameters, even though they incorporate highly similar functions, so they are mutually incompatible.
A uniform profile view with Anybus technology
With the definition of a standardised host software interface for the Anybus-CC modules, HMS has long since proven that it is possible to reconcile the differences between the various bus protocols and map them into a standardised software interface: the Anybus application interface (API). By using Anybus modules, equipment manufacturers can keep their device software largely independent of the details of individual bus systems and link their equipment to a large number of diverse bus systems (Picture 2). Based on this proven mechanism, HMS has now extended the concept to realise a uniform view of the various drive profiles and implemented it in Anybus modules with integrated profile functions.
Object orientation as the key to success
The Anybus-CC application interface is object-oriented (Picture 3). The standard scope includes objects (application data instances - ADIs) for cyclic process data and acyclic parameter data, as well as diagnostic and alarm functions. In addition to these object definitions, HMS has now defined objects specific to drive profiles. For example, there are ADIs for speed (rpm) setpoint and actual values, torque, acceleration, and minimum and maximum speed values, to mention only a few. Properties such as units of measure or reference values (rpm or percentage of maximum value) can be assigned to each object. The interface also includes a carefully conceived control and status word that contains the current status of the individual drive. The state machine of the drive must be executed in the host software. In addition to the predefined objects provided by HMS, manufacturer-specific objects can be created. These objects can be stored physically either in the module memory or in the host software. Updates are performed using standardised access mechanisms. The access speed is essentially determined by where the object is stored. The best performance is obtained by accessing parameters managed inside the module. An additional handshake cycle is necessary for access to parameters managed in the host.
Standardised hardware interface In addition to a standardised software interface, all intelligent Anybus-CC communication modules have a standardised hardware interface. There are two options for linking an Anybus module to the host electronics: an 8-bit parallel interface with a dual-port RAM, or a fast serial interface with a UART. The modules require a 3.3-V supply voltage and feature low power consumption.
Flexibility in CompactFlash format The form factor of the Anybus-CC modules is similar to the CompactFlash card. A 50-way CompactFlash connector is used to interface against the application in the device. Anybus-CC modules are available in enclosed and open versions. The enclosed version has the ad-vantage that the module can be plugged into the drive at any point in the supply chain between the drive manufacturer and the end user, with no need for compliance with special protection rules.
Reduce development costs by up to 70%
Using standard Anybus-CC modules already enables cost savings of up to 70% in the development of a universal communication interface. If the drive profile functions are also used, additional added value can be achieved and the equipment manufacturer can profit enormously from HMS´s comprehensive expertise. This means that even with large product volumes, Anybus-CC modules are an attractive alternative to in-house development of communication interfaces for drive units and many other types of automation equipment.
HMS released the entire drive profile concept in end of 2009 and will expand with the CC-Link module in Q2 2010. HMS can provide equipment manufacturers with design-in support for the Anybus host interface by means of free developer training courses along with extensive sample software and reference circuit designs. In addition, starter kits are available for rapid familiarisation with the new technology.
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