First PLC for Windows CE

It's not often you see the price leader in a market snare the role of technology leader. Yet this is the case with PLCDirect's (Cumming, Ga.) introduction of two new control platforms for the Microsoft Windows CE operating system (OS).The WinPLC and RuntimePC combine PC-based control software, Ethernet ports, PLC I/O, and flat-panel display hardware with Windows CE.

By Jane S. Gerold, Control Engineering September 1, 1998


Software for control

PC-based control

Programmable logic control

Microsoft Windows software

Sidebars: A PC on a PLC for under $1,500 Oh, say can you CE?

It’s not often you see the price leader in a market snare the role of technology leader. Yet this is the case with PLC Direct ‘s (Cumming, Ga.) introduction of two new control platforms for the Microsoft Windows CE operating system (OS).

The WinPLC and RuntimePC combine PC-based control software, Ethernet ports, PLC I/O, and flat-panel display hardware with Windows CE. This real-time, small footprint, diskless OS was designed from the ground up for embedded systems. (See box next page, for additional Windows CE information). WinPLC builds on PLC Direct ‘s DL205 programmable controller family; the RuntimePC platform is a diskless Windows CE industrial PC.

From its humble beginnings as the “world’s smallest PLC company,” PLC Direct has expanded its sales and warehousing operations to a new four-story facility north of Atlanta. Founder and president Tim Hohmann credits his company’s success to being, “an underdog with a winning attitude.” This winning attitude built a “federation” of companies dedicated to highest-performance solutions at lowest costs. PLC Direct markets and sells products from the federation companies through its 600-item catalog.

The development of the new Windows CE-based controllers and software required cooperation and teamwork among the following federation companies:

Host Engineering—WinPLC;

Think & Do—Windows CE control software;

PLC Direct —DL205 I/O and PLC rack.

These products, along with the RuntimePC manufactured by Ann Arbor Technologies, merge automation with commercial PC technologies.

PC vs. PLC, or both?

The development cycle for a proprietary automation product is typically three to five years. This significantly reduces useful produce life, at least in terms of current technology implementation.

One of the strongest arguments for open PC technology in automation is to deploy commercial developments as they occur, rather than three to five years down the road. This has resulted in the great PC vs. PLC debate.

With Windows CE, both PCs and PLCs hold merit, depending on the application. Windows CE control software, running in realtime on a PLC, can connect to existing I/O devices while still providing open access to standard networking and software. Windows CE application software running on a diskless industrial PC combines real-time control and robustness with an intuitive human-machine interface.

Federation companies have implemented Windows CE solutions using Ethernet as the communication backbone. Ethernet was chosen because it, also, is a commercial standard with highest performance for lowest cost. (Driver cards are available for $75.) The WinPLC CPU communicates with DL205 I/O modules over the backplane, but offers Ethernet and serial ports for PC and operator interface communication. The RuntimePC includes a built-in Ethernet hub with three ports to talk to PLC Direct I/O bases and one port for network communication.

Think & Do software, which is available in Windows CE and NT versions, provides the control engine for both hardware platforms. Programmed with flowcharts, the software integrates logic control, motion control, and HMI.

Windows CE addresses barriers to PLC- and PC-based control. Its small footprint and reduced hardware requirements lower system costs. It is realtime and robust for industrial applications. It leverages commercial developments for software and communications and is portable across multiple platforms, helping bridge the PC and PLC worlds.

A PC on a PLC for under $1,500

Performance is good, packaging is good, but what about price? Here’s where the WinPLC and RuntimePC really shine.

Following PLCDirect’s motto “twice the performance, half the price,” the WinPLC carries a price tag of under $1,500 for a typical system.

WinPLC CPU with Think & Do runtime software on Windows CE$699

DL205 PLC rack…$130

32 dc inputs…$146

32 dc outputs…$152

4in/2out analog…$323


To add operator interface, users can choose from a variety of displays, including the DirectTouch color flat-panel display priced at $799.

The RuntimePC combines Windows CE-based control and operator interface in one flat-panel package. With Think & Do runtime control software, three Ethernet ports to communicate with PLC I/O devices, one Ethernet SCADA port, and NEMA 4-sealed 12.1-in. color touch display, the unit lists for $3,495.

Both the WinPLC and RuntimePC will be available in November through PLCDirect.

Oh, say can you CE?

From handheld PCs to web phones to industrial controllers, Microsoft’s Windows CE operating system brings mighty performance to micro platforms.

Windows CE was developed for real-time, embedded systems. It borrows from the best of Microsoft’s other operating systems, such as the Win32 API (application programming interface), but eliminates high overhead features not required for embedded control. As such, its architects achieved the design goals of:

Small footprint, using modular, customizable components;

Execution directly from ROM, for diskless control;

Standardization on the Win32 API, to leverage programming knowledge; and

Portable across a wide variety of hardware platforms, including AMD, Hitachi, Intel, Motorola, NEC, and Philips.

Getting real

For industrial control, a real-time operating system is as critical as footprint and portability. To be realtime, an OS must support:

Multithreading and preemption;

Thread priority;

Priority inheritance; and

Predictable synchronization.

Windows CE delivers real-time control by supporting 32 simultaneous applications, or processes, with eight levels of thread priority. A process consists of one or more threads, each representing an independent portion of the process. A time-slice algorithm schedules execution of the threads, with preemption based solely on the thread’s priority. For synchronization between threads, Windows CE uses a set of “wait objects” such as event and critical section.

To leverage application software, Windows CE runs ActiveX controls and COM (component object model) components without size or speed penalties. Windows CE can deploy a vast array of object-based modules in networked systems or over the Internet.

By delivering real-time functionality in a standard programming environment, Windows CE may supply the missing link between industrial control and commercial development.