Peterborough, Ontario—Leading automation suppliers are taking a plug-in fieldbus translator approach to multiplenetwork protocol support be-cause it's faster and more cost effective than doing the work in house. For example, when Siemens Milltronics Process Instruments Inc. was planning its new generation of industrial sensors, the company anticipated the growing demand for networking capabilities. It already had a proprietary Dolphin protocol that, with an interface converter, would convert to the popular industry standard Modbus®. "However," recounts industry consultant James Powell, "many customers wanted to interface with Allen-Bradley® Remote IO, Profibus, and DeviceNet."
After considering all the networking options available, including developing another proprietary interface, the company determined it would be faster and more cost effective to use a plug-in fieldbus translator using technology from HMS Industrial Networks Inc. (Chicago, IL). "It has proven to be a good solution," notes Powell. And since HMS fieldbus devices are also used in products from Rockwell Automation, Cutler-Hammer, Fuji, Hitachi, ABB, Schneider Electric, Square D, Omron, and GE Fanuc, it seems leading automation suppliers agree.
Just six years ago, the concept of developing plug-in exchange modules for all of the different fieldbuses was in its infancy, according to HMS VP Staffan Dahlström. "Because of our networking experience, companies such as ABB were asking us for electronic products with networking," Dahlström explains. When HMS engineers found themselves recreating the same types of networks over and over again, they decided to create a generic circuit board that customers could just plug into their product. "The beauty of the product that we designed was that it was a generic translator for all the different languages in industrial networking," Dahlström says.
It was this circuit board, with everything on it, which Milltronics adapted into a series of plug-in communications modules it calls SmartLinx®, launched in 1997. Since then, Milltronics has been incorporating HMS AnyBus® interfaces into its products. First it was the AnyBus DT and then the AnyBus S. Having a circuit board with everything on it provides a convenient, comprehensive solution, according to Dahlström. "But today's requirement is for higher levels of integration at a lower cost. In certain uses, such as very simple or high volume applications, the size and cost of the board was not cost-effective, although the same functionality was desired."
In response, HMS developed the AnyBus IC that made its North American debut at the National Design Engineering Show this year in Chicago. Engineers took the most popular functions of the AnyBus S and put them into one plug-in module. "In the process, using cutting-edge miniaturization," explains Dahlström, "we made it five times smaller for half the price."
AnyBus uses either an asynchronous serial interface connected directly to the application processor, or a synchronous serial interface connected via shift registers against the application.
According to Trevor Lang, HMS's regional sales manager, "Fieldbuses emerged to reduce installation costs and provide interoperability between multiple vendors' devices. So the AnyBus IC is the next logical next step." The hybrid technology, on which the AnyBus IC is based, is already used in millions of consumer electronics products, according to Lang. "It is not a set of new protocol ASICs," he says, "rather it is based on proven technology from the market leaders and industry standard compatibility is inherent."
In the AnyBus IC, all analog and digital functions are integrated in a single chip. It has a 32-pin dual-inline footprint (42 × 21 × 12 mm) and can be automatically inserted and soldered. All the different types share the same generic communication interface towards the application. It is suitable for simple devices such as sensors and actuators, as well as for intelligent devices with a separate micro-controller.
When designing a new product that will use an AnyBus IC, before the circuit board is laid out, the developer typically downloads design guides that have all the connector information. If a simple device does not have a microprocessor—such as valve terminals, some sensors, actuators, and modular I/O—the AnyBus IC has a clocked shift register interface that can be connected to up to 16 bytes of input data and 16 bytes of output data in addition to addressing configuration switches and diagnostic LEDs.
For more information about AnyBus IC from HMS: Enter 535