In its latest study, "PLC Worldwide Outlook, Market Analysis & Forecast Through 2006," ARC says the PLC market will revive from the doldrums of 2001, is growing rapidly, and the industrial PC is not a threat. This report is much more in line with what is actually happening in the market.
For example, the study says nano and micro PLCs are getting networking capability and increased functionality, and are beginning to replace larger PLCs.
We can add to that observation we see little or no development in larger PLCs. The prices continue to fall, so you can now purchase a powerful PLC for a pittance. At the low end, PLCs are becoming commodity controls.
PLC functions and capabilities are being usurped by a new class of emerging products that are best called general machine controllers, or GMCs. These devices are a mix of motion control, PC architectures, Windows operating systems, PLC programming in IEC 61131 languages, and network communications. Many GMCs are being offered by traditional PLC vendors, which call them a variety of names, including automation controllers, automation platforms, or industrial controllers.
The following is the second of three installments on PLCs. Look for the third installment the first week of November.
Universal Controllers Get COTS
The RX7i PACSystems Programmable Automation Controller is built on standard embedded architecture with commercial deterministic operating systems. It supports distributed I/O via Ethernet, Profibus, DeviceNet, and Genius networks; has four times the speed of the company's existing PLC backplanes; and provides up to 10 MB of memory for programming and documentation storage. The VME64-based device supports all standard VME modules including Series 90-70 I/O.
Machine Controls Get Virtual Control Technology
Web-enabled 5104 Series Blue Fusion controller has virtual I/O support that enables users to connect two controllers together over an Ethernet connection in a master/slave configuration, and run a control program on the master that has full access to the resources on the slave unit. This essentially doubles the resources available, providing up to 100 I/O points or 13 axes of motion control, plus additional resources and performance for more demanding applications.
PCI Motion Board
ACR8020 PCI bus-based controller has a 150/120 MHz floating-point DSP to provide the speed and computational power to drive 16 servo or stepper motors from one 16-axis group. Board has eight channels of analog inputs. With two expansion boards, it can drive up to 24 axes of motion control. Each expansion board has 10 encoder inputs, plus two high-speed digital triggered outputs to drive lasers or a peripheral device, such as a vision system.
Stepping Motor With Motion Control
The MDrive23 NEMA size 23 high-torque stepping motor comes with a complete programmable motion controller. It communicates over RS-485, which allows point-to-point or multiple unit configurations using one communication port. Addressing and hardware support up to 62 uniquely addressed units communicating over a single line. It has four 5-24 V general-purpose I/O lines, one 10-bit analog input, 0-5 MHz step clock rate, microstep resolution up to 51,200 steps per revolution, and full instruction set.
Intelligent Motion Systems
Control by the Book
BX2 Motion-and-Machine Controller is about the size of a textbook, but contains up to eight axes of control, up to six on-board drives supporting servos to 1,600 W, and 46 onboard digital I/O points. The controllers' real-time operating system incorporates a comprehensive set of motion control functions. Syntax-free programming environment simplifies application development and tool integration. Built-in Ethernet supports controller networking up to 56 axes and a variety of external I/O expansion modules.
Berkeley Process Control
The OEM2500 Coyote single-board has two standard models--one with Ethernet, one without--and the unit can be customized to user-specified configurations when manufactured in volume orders. It has a 29.4 MHz Rabbit 3000 microprocessor, 256K Flash and 128K SRAM, five serial ports, 16 I/O, four LEDs, and 10 timers. Options include more memory, 10BaseT or 10/100BaseT Ethernet, and onboard backup battery.
The DIN rail mounted Logo! logic module is available with a backlight display clearly showing values, parameters, and text on the same line. Redesigned SoftComfort v. 4.0 software provides function block and ladder logic options--130 blocks are available per application in any combination, including timers, counters, and others. The device can replace conventional switching devices and requires less wiring and cabinet space.
Siemens E & A