PLC Users Like What They Have

The old saying “No News is Good News,” certainly seems to apply in the world of programmable logic controllers (PLCs). Control Engineering’s 2006 PLC Product Research Survey, with help from Reed Corporate Research, indicates that PLC users seem to be happy, or, at least complacent. They’re happy with their suppliers.

By C.G. Masi November 1, 2006
  • PLC satisfaction

  • 44% consider PACs

  • Equal or higher spending

  • More Ethernet connections

The old saying “No News is Good News,” certainly seems to apply in the world of programmable logic controllers (PLCs). Control Engineering ’s 2006 PLC Product Research Survey, with help from Reed Corporate Research, indicates that PLC users seem to be happy, or, at least complacent. They’re happy with their suppliers. They’re happy with the products their suppliers offer. They’re happy programming those products with ladder logic. They plan to do more of the same. And, more than 90% plan to buy as many or more PLCs in the next 12 months.

Among 114 Control Engineering subscribers answering the survey who say they specify, recommend, and/or buy PLCs 60% said they were “very satisfied” with their current PLC supplier, 30% said they were “somewhat dissatisfied,” and only 3% said they were “very dissatisfied.” This is good news for vendors selling the most popular PLC models, especially Rockwell Automation, whom 66% of respondents said they purchased PLCs from during the past 12 months. It was less good for next-tier manufacturers, from whom between 20% and 25% of respondents reported purchasing PLCs; 16 other vendors with less than 10% marketshare could face challenges increasing that share, with so much satisfaction with present suppliers.

What about the market as a whole? Do respondents think they’ll increase their spending on PLCs? Last year, 51% thought they would.

This year 40% thought they would increase spending, with about 50% thinking their number of PLC purchases would remain the same. For last year and this year just 8% thought they’d buy fewer PLCs in the next 12 months..

PLC programming language choice saw little change from last year.

Among PLC users there’s some interest in programmable automation controllers (PACs), which are rugged PCs in a PLC form factor. Fully 44% of respondents are considering using PACs for automation control. However, they seem to be thinking about PACs for new installations. Only 2% said they were replacing existing PLC-based automation with PAC-based control.

Not everyone is on the PAC bandwagon, though. Some 39% of respondents said they were not using or even considering PACs for their control applications.

Respondents also seemed satisfied with their programming options. Choice of programming languages was similar to 2005 survey results. Ladder diagrams topped the chart with 96%, compared to 94% in 2005. The only significant gainer was flow charts, rising from 13% in 2005 to 25% in the current survey.

Amost all (97%) PLC users are satisfied with their suppliers.

Not surprisingly, when interconnecting PLCs to larger control systems, use of the Ethernet physical layer was among the big winners, being cited by 86% of respondents versus only 75% in the 2005 survey. Other non-proprietary standard protocols, such as DeviceNet and ControlNet, showed significant gains as well.

“Ethernet… is widely understood, easy to implement, and very affordable,” David D. Harris, PLC product manager at Eaton points out. “It also reduces labor costs by allowing users to connect to PLCs throughout the factory floor from a single workstation. Users are no longer required to traverse the factory floor carrying a laptop.”

Wireless interconnectivity for PLCs, remained around 40% both years.

Altogether, the survey shows that, while PLC users are paying attention to technical advances, they have little motivation to apply them. Apparently, perceived gains do not justify the costs of switching from tried-and-true to something else.

PLC products

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Four-axis motion control

Allen-Bradley’s CompactLogix 1768-L43 controller from Rockwell Automation controls up to four axes of motion. Designed to be ideal for material handling, packaging, metal forming, and other applications requiring speed, motion synchronization and information-sharing capabilities, the unit fits into a small, modular footprint. The controller combines motion and sequential control into an integrated multitasking platform to help users lower system costs, simplify installation, and ease maintenance. Network support includes DeviceNet, ControlNet, and EtherNet/IP, enabling a seamless flow of information from the smallest device through the enterprise business system. It supports removable CompactFlash memory that can be used as a program and firmware storage area, providing the user with ability to archive projects that can be loaded to multiple controllers.

Rockwell Automation

Application portability across platforms

The new PACSystems RX3i controller is the latest addition to the PACSystems family of PACs. Like the rest of the family, the PACSystems RX3i features one control engine and universal programming environment to provide application portability across multiple hardware platforms and deliver a convergence of control choices. Using the same control engine as the PACSystems RX7i, the new PACSystems RX3i is said to offer a high level of automation functionality in a compact, cost-effective package. The portable control engine provides high performance on several platforms, allowing OEMs and end-users to choose control system hardware that best suits their needs. Features include dual backplane bus support per module slot; high-speed, PCI-based for fast throughput of new advanced I/O Serial backplane for easy migration of existing Series 90-30 I/O; and Intel 300 MHz CPU for advanced programming and performance with 10 Mbytes memory; and memory for ladder logic documentation and machine documentation in the controller to reduce downtime and improve troubleshooting. Communications support includes Ethernet, Genius, Profibus, DeviceNet, and serial, with support for high density discrete I/O modules, universal analog (TC, RTD, strain gauge, voltage and current configurable per channel), isolated analog, high-density analog, and high-speed.

GE Fanuc

Wireless Ethernet communication for PLCs

Schneider Electric’s versatile Telemecanique Twido nanocontroller, said to be the first nano PLC with embedded Ethernet capability, can now be programmed with Bluetooth wireless or Ethernet. The latest Twido enhancements extend its functionality and ease of use in many applications, the company says. New wireless capabilities simplify diagnostics and troubleshooting for OEMs and plant personnel. Users can now remotely monitor and control Twido PLCs over Ethernet, using the new embedded Ethernet connection or a new Modbus-to-Ethernet bridge. Bluetooth wireless capability also makes set-up and adjustment easier. Online programming capabilities are incorporated in enhanced TwidoSoft v3.0 software, which simplifies controller programming, allowing users to modify program instructions in Instruction List or Ladder Logic while the controller is in run mode.

Schneider Electric

Ethernet-based PAC

Opto 22 Snap PACs are high-performance, multi-domain, Ethernet-based industrial automation controllers suitable for applications in automation and control, remote monitoring, and data acquisition. The Snap-PAC-S1 is a standalone controller suitable for distributed control systems and applications with high I/O point counts or complex architectures. The unit features a 32-bit multitasking processor with floating point processor, 32 MB of RAM, 16 MB of flash memory, and 8 MB of battery-backed RAM. It offers two independent, auto-negotiating 10/100 Mbps Ethernet interfaces that can be configured to create dual Ethernet networks for segmenting I/O and host traffic, or to create redundant Ethernet link segments for critical applications. Also included are one RS-485 port and two RS-232 ports, one of which offers full handshaking control. The Snap PAC-R1 is an under-$1000 “on-the-I/O-rack” controller designed for cell control and smaller I/O point count applications. It features two independent, auto-negotiating 10/100 Mbps Ethernet interfaces that can be used for network segmenting or Ethernet link redundancy. Additionally, the unit features a 32-bit multitasking processor with floating point unit; 16 MB of RAM, 8 MB of flash memory, and 2 MB of battery-backed RAM; and one RS-232 port with full handshaking control.

Opto 22

PLC with low-cost Ethernet

BX9000 Bus Terminal Controller from Beckhoff Automation has made control over Ethernet more scalable. Priced about $500, the unit is said to deliver integrated PLC functionality at an exceptional price. The BX9000 is positioned between the Beckhoff BC series of bus terminal Controllers and the CX series of Embedded PCs. Like all DIN rail mounted controllers, the BX9000 features a direct connection to the entire Bus Terminal I/O system of over 180 terminal designs. BX series controllers feature an illuminated display with 2 lines of 16 characters each and a joystick switch for user interaction or diagnostic information. With a 256 kB program memory and a 256-kB data memory, the unit provides increased memory capacity and additional interfaces. It also interfaces with Modbus TCP, ADS/TCP and ADS/UDP, BootP, DHCP, SNTP and SMTP. With an integrated real-time clock, the controller can be used in decentralized applications for which the time or the day of the week is important.

Beckhoff Automation

Flexible, small footprint PLC

Eaton Corp.’s latest programmable logic controller, the ELC, delivers abundant module selection in a small package. One-third the size of competitive offerings, ELC can retrofit more input/output (I/O) connections into existing space, or deliver cost savings by reducing cabinet size. Despite compact size, users benefit from large-PLC features, including multiple communications ports, remote I/O ability, data collection storage area, high-speed counters, high speed pulse outputs, ramps, trapezoids, floating point math, interrupts, timer resolution to 1 ms, PIDs, and more. Flexibility is one of the unit’s key benefits. Users can expand it from 10 to 256 I/O ports using the same controller. The ELC’s no-rack design allows modules to be added by simply snapping them into their mating connectors. Slave connectivity can be added to DeviceNet, Profibus, or Modbus TCP, and users can share data with other networks.

Eaton Corp.

Micro PLCs with high speed, connectivity

Mitsubishi Electric Automation’s FX3U Series line of next-generation SuperMicro programmable logic controllers offer excellent execution speed, performance-enhancing instructions, and unparalleled connectivity, the company says. The new devices, which are backward-compatible with Mitsubishi Electric’s FX2N series, include relay and transistor base units, software and most peripherals. Ideal for nearly any machine control application, the FX3U delivers faster throughput, larger memory (800% more than the previous series), improved motion integration and broader network connectivity. Unlike rack-based platforms that have separate power supplies, CPUs and input/out modules, the FX3U compact PLC integrates all these components in a single platform. What’s more, the FX3U has the most memory and fastest instruction processing time of any PLC in its class and is the only compact PLC with a Profibus Master and a high-speed fiber-optic networking card for servo amplifier control. It has left- and right-hand buses for communication, analog I/O, and high-speed input, and high-speed output modules, to increase system flexibility and application opportunities.

Mitsubishi Electric Automation

Controller has BASIC-style programming

Baldor’s Flex+Drive II features an integrated motion controller with BASIC-style keywords for motion tasks as well as PLC-style machine control I/O handling. The unit handles index moves using a simple preset table interface. It also provides software gearing and on-the-fly adjustments. Up to 16 pre-sets can be loaded with absolute/relative position, speeds, accel/decel. Using the onboard I/O functionality, requests for new indexes are controlled using 4 digital inputs. Programs can be written and tested in minutes. The drive provides complete standalone machinery solutions with expansion capability to 256 presets and additional digital I/O connections for controlling other machine functions including HMI using fieldbus communications, such as with CANopen, DeviceNet, or Profibus-DP. It has a wide range of uses in packaging, conveying, labeling, loading, assembly and other manufacturing applications. For some, its single-axis capability is enough. For larger automation requirements, it may be used as an element of a distributed multi-axis system.


Open, flexible PLC system

Rexroth IndraLogic PLC system sets new standards for open and flexible automation. IEC61131-3 compliant, IndraLogic can be PC-based, controller-based, or drive-based, providing maximum flexibility to machine builders. The programming system uses a standardized function library and provides programmers with an intuitive user interface for performing offline and online functions including monitoring, debugging, and forcing. The PLC is compact in design and simple to install. With multiple open network interfaces, it provides flexibility for machine builders to configure the system for various applications. To run on a variety of frameworks, it uses the Rexroth IndraWorks engineering framework, based on Microsoft .Net technology.


Celeron processor PAC

Based on the latest Intel Celeron processor technology, the X20 CPUs from B&R Industrial Automation utilize cycle times as short as 200holds task-specific data and remnant variables. The CPUs have one RJ45 connection for TCP/IP communication, and a second for Ethernet Powerlink. Two ports are available for USB devices and an RS-232 connection. The X20 CPU and accompanying X20 I/O modules can be mounted and removed as a unit from astandard mounting rail, providing high performance, and many standard interfaces and interface modules for expansions in a compact package. CPU dimensions match those of the X20 modules, which prevents unnecessary waste of space in the switching cabinet.

B&R Industrial Automation

ONLINE extra

Profinet programmability
The 750-840 Profinet-enabled programmable controller from Wago can be used stand-alone or as an intelligent slave in a distributed/decentralized control network. Complying with the Profinet RT specification V 2.01 the unit features 32-bit multi-tasking CPU, 256KB program memory, 128KB data memory, 24KB of retentive memory, and a real-time clock. The controller also supports HTTP, BootP, DHCP, DNS, SNTP, FTP, SNMP, and SMTP for system management and diagnostics. The company’s IEC 61131-3 programming tool, Wago-I/O-PRO CAA, supports all five programming languages and offers a built-in visualization tool. Housed in a modular, compact, DIN rail mount housing (2 x 2.56 x 3.94 in.; width, height, length), the 750-840 fits in small spaces and reduces costs associated with traditional rack based PLCs. Compatibility with the company’s 750 and 753 Series I/O modules allows engineers to use over 200 digital, analog, and special function I/O modules and ensures connectivity to virtually all signal types. For more information, contact Wago by telephone at 1-800-DIN-RAIL, by email at, or visit the company’s Website at

Read about

. Top 5: According to survey results mentioned in the article above, the top five PLC suppliers were: Rockwell-Automation/Allen-Bradley, Siemens, GE Fanuc, Automation Direct (Koyo), and Schneider Electric (Modicon, Square D, Telemecanique).Also read the 2005 Product Research article that follows.

PLCs Maximize Machine, Motion Control

: Control engineers now have at their disposal a wide variety of logic devices to program processes and machines. Computers and computer technology provide almost unlimited control possibilities no matter what the application. PLCs remain a strong part of the mix—a recent survey finds more than half expect to increase PLC spending in the next 12 months.