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Integrated Controller Targets Cost, Reliability
Off-the-shelf components and robust operating system bring down cost and boost up-time
Rick DeMeis -- Design News, September 8, 2003
Useful, yet easy to use—such traits can often seem like conflicting requirements. But the engineers who developed the PC-based ServoWire Motion & Logic Controller (SMLC) just announced by Rochester, NY-based ORMEC (www.ormec.com) think they have hit the target for tight integration, low cost, and, above all, reliability. And, they say, the controller's ease-of-use allows systems to be up and running in short order.
To achieve these characteristics, the developers combined ServoWire Soft Motion technology with CoDeSys IEC 61131-3 world-standard programming from Smart Software Solutions (www.3s-software.com) for motion and I/O control. According to Dave Carr, ORMEC VP of product marketing and development, the vendor-independent PLCopen-based motion technology uses function blocks ported over from ORMEC's DOS-based Orion system for coordinated motion, electronic gearing, hardware triggers, etc., so no programming is required.
The engineers minimized hardware costs by using commercial off-the-shelf components. The latter include Pentium Class processors and industry standard network interfaces (Ethernet, Profibus DP, Modbus, and IEEE 1394 FireWire) for connectivity options. For handling all these choices, ORMEC's designers partnered with WAGO (www.wago.com) to integrate the connectivity technology company's 750 Series networked I/O with the ServoWire controller. Use of FireWire I/O permits a single network for both motion and I/O.
Developers also chose the QNX Software Systems (www.qnx.com) Neutrino Real Time Operating System (RTOS) for its 20+ year track record for high reliability applications, such as nuclear power plants, medical systems, air traffic control, and high speed trains.
This reliability comes in part from the RTOS micro kernel, which features full memory protection if an application or driver goes down, notes QNX Regional Sales Manager Bob Kilbride. 'No component can invade the memory space of another,' he adds. Plus, additional non-shared component memory is simply plugged into the memory bus.
One wire
The advent of open standard FireWire single-wire connectivity allows users to connect up to 16 ServoWire drives in initial versions at the servo loop update rate of upwards of 4 kHz. These digital drives support actuator technologies that include brushless rotary and linear motors, dc brush motors, and voice coils. And, here's where ease of use also comes into play: Operators can configure the drives over the ServoWire network, eliminating manual configuration and off-line configuration utilities—saving time and cutting cost. The software also has a 'scope window' that displays functions for optimizing servo performance and time history plots that can serve as the basis for preventive maintenance scheduling. As new drive upgrades and firmware revisions become available, ORMEC will e-mail them to users for similarly updating their systems through the network.
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Thnaks for the memories: The SMLC controller has flash memory for application program storage and battery-backed RAM for non-volatile data storage. Without need for a hard disk (with its longer time to store backup data), reliability is alos improved. |
But ORMEC is not the first to market with FireWire integrated motion control. Aerotech (www.aerotech.com) out of Pittsburgh, PA has had its Windows-based Automation 3200, with 20 kHz update rate and 32-axis capability, on the market for just over a year. Implications of ServoWire's entry into the motion and logic control market are offered by Sal Spada, research director for Manufacturing Advisory Services at ARC Advisory Group, Dedham, MA-based analysts of the automation market: 'This allows ORMEC to bring to the market its application expertise on an industry standard platform. They are leveraging off-the-shelf product value to compete in a market where OEMs are looking for wide ranging capability, such as adding or subtracting features efficiently, to lower integration costs,' he notes. Specifically, Spada cites the broad ServoWire drive line, whose units range in output from 300W to 15 kW. 'It is not tied to one motor vendor, giving people choice.'
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