Distributed automation has exceptional performance

PowerDNA uses standard Ethernet cabling, and is optimised for real-time control applications requiring both large numbers of analogue and digital I/O points as well as extremely fast response

Dedicated protocol gives distributed automation exceptional realtime performance Under PC control and using conventional Ethernet cabling, the PowerDNA system can poll 800 mixed I/O points in less than one millisecond.

Users can configure the remote I/O Cubes with a variety of analogue, digital, serial and motion I/O options.

PowerDNA (which refers to Distributed, Networked Automation and Control) is a system that sets new benchmarks for hard real-time I/O using standard Ethernet cabling.

Developed by United Electronic Industries, the modular system is optimised for real-time control applications requiring both large numbers of analogue and digital I/O points as well as extremely fast response.

Thanks to the patent-pending DaqBIOS protocol, which transfers commands and data over Ethernet hardware in a deterministic fashion, a PowerDNA system consisting of a PCI/PXI-based controller and multiple distributed nodes with more than 800 mixed analogue and digital I/O points can guarantee a response in less than 1 msec.

A wide selection of I/O configurations is available from the factory.

"We have listened to the voice of the customer and have developed PowerDNA, which meets the needs for distributed hard real-time I/O for the next decade," comments Shaun Miller, president of UEI.

"For several years engineers could purchase Ethernet-based I/O but with insufficient real-time response to address future system requirements.

However, the development of the PowerDNA DaqBIOS protocol has solved this problem".

At the highest level, PowerDNA consists of a Central Controller card that fits into a host PC or PXI/CompactPCI system, and it supplies either one, two or four Ethernet ports.

To each of these ports, users can attach as many as 64 I/O Cubes.

Each I/O Cube in turn consists of a metal enclosure that contains a Communications layer, a CPU layer with an embedded real-time kernel, and positions for either three or six I/O layers.

Customers select the desired functionality from a range of I/O layers, which are factory installed, configured and calibrated.

Users program their applications in C using a straightforward API that provides access to all hardware functionality.

After compiling an application on the host PC, engineers can download it to an I/O Cube in several ways: over the Ethernet, over a serial link, over a USB port or even with a PDA equipped with an infra-red link.

The application can run under host control or as a standalone task.

The Central Controller resides in a PC or PXI/CompactPCI system, and it is equipped with a 333-MHz PowerPC processor, 128M bytes of RAM and 64M bytes of CompactFlash memory that stores programs and a mini-OS.

The controller offers from one to four 100-BaseT network interfaces, each of which can control as many as 64 I/O modules.

The controllers can run the high-performance DaqBIOS protocol, but they also support standard protocols such as TCP/IP that allow users to integrate factory-floor tasks with an enterprise system.

As for software, the Central Controller executes QNX, Real-time Linux or VXWorks.

And even when supporting hard real-time operation, 80% of the processor time is available to run a user application.

Each I/O Cube starts with a CPU layer, which contains a ColdFire CPU running at 66 MHz plus 16M bytes of SDRAM and 4M bytes of Flash memory.

This layer also provides an IrDA interface so users can field-configure the CPU module with the assistance of any infrared-equipped PDA.

Next, the I/O Cube also comes with the Network layer, which provides two RJ45 jacks for daisychaining the Ethernet link to other I/O Cubes; it also provides a USB port and a serial port over which users can download new programs or upload process data.

Users also daisy-chain power from cube to cube within this layer.

The small unit also holds as many as six I/O layers, each connecting to the CPU layer over a 32-bit 33-MHz bus with opto-isolation, so errant field signals cannot disrupt system operation.

A 5-layer I/O Cube with room for three I/O layers measures 4 x 4 x 4 inches, while the 8-layer version is 6 x 4 x 4 inches.

When configuring an I/O Cube, users can select from several I/O Layers: analogue input (16 channels, 16-bit resolution, 100k sample/sec digitisation rate); analogue output (8 channels, 16-bit resolution, 100k sample/sec update rate); temperature measurement (24 channels, 24-bit A/D, direct sensor connection); digital I/O (with either 8 or 16 bidirectional lines); communication (eight RS232/485 ports); 4-axis motion control.

The Central Controller communicates through the I/O Cube Network layer to individual I/O layers using the patent-pending DaqBIOS protocol.

It employs either isosynchronous operation with time sharing, or variable timing in a broadcast scheme, or both.

Because the protocol is optimised for process applications, the overhead per message is extremely low and the scheme achieves impressive response times.

For example, in a system with 16 modules (3072 I/O points) using variable timing, the time required to communicate with all I/Os is less than 1 msec.

Price and Availability: the DNA-CC Central Controller starts at $2500 (USD) with one communications port; and an I/O Cube with the Network and CPU layers along with three open I/O-layer positions costs USD700; an I/O Cube with six open I/O layers sells for USD900.

The I/O layers themselves range from USD400 (8-channel analog output) to USD1800 (4-axis motion control).

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