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CP-Link 3 – Ethernet-based multi-display link

Tuesday, November 25, 2008: Beckhoff Automation (Pty) Ltd

Designed for flexible operation and visualisation based on technology standards

With CP-Link 3 Beckhoff presents a new operating and visualisation concept for flexible connection of up to 255 Ethernet Panels and Panel PCs with an Industrial PC. CP-Link 3 is a pure software solution based entirely on standard hardware (Ethernet) and IP-based protocol for transfer of images. Networking can be done using cost-effective, standard Ethernet cables (CAT 5) which are suitable for drag chains.

Using the CP-Link concept, Beckhoff has relied on remote operating elements since as far back as 1998; i.e. the control and display elements make up an independent unit, separate from the control level. The computer is housed in a control cabinet. The flexible positioning of the Control Panels gives the user a great deal of scope. While the existing CP-Link 1 and CP-Link 2 solutions are based on special hardware components, CP-Link 3 is a pure software solution.

In contrast to previous solutions, the CP-Link 3 concept is based entirely on standard technologies: 100 Mbit/s Ethernet and IP protocol. The screen contents are captured by a virtual graphic adapter in the host PC and sent using Ethernet to one or more Beckhoff Ethernet Panels with Windows operating systems (CE and XP Embedded, XP). For display communication, TCP/IP or UDP/IP (Multicast) can be configured, depending on the operating mode.

In terms of screen display a distinction is made between three operating modes:

• Single Desktop: A virtual graphic adapter shows the image of the host PC on a display connected via Ethernet.
• Extended Desktop: One or several virtual graphic adapters are used as extensions to the host PC desktop. In this way, windows can be extended to up to 9 displays.
• Multi Desktop: All connected displays show the same image (via UDP/IP up to 255 panels). In multi desktop mode, an input can be made to each panel at the same time. The displays can be interlocked (mouse and keyboard) to coordinate the inputs.

The host PC transfers image signals, touch screen and special key functions as well as “Virtual USB” to the Panels. Virtual USB emulates a USB root hub in the host PC. If a USB device is plugged into an Ethernet Panel, the virtual hub logs the device on to the operating system of the host PC and transparently transmits the ensuing communication. For the operating system, the USB device behaves as though it was directly connected to the PC. Virtual USB transfers the standards USB 1.1 and USB 2.0.

The CP-Link 3 concept is supported by all Beckhoff Ethernet Panels and Panel PCs. The requirement for this is the CP-Link 3 client software and Windows CE or XP Embedded as an operating system. The aluminium Control Panels have high-quality TFT displays in different sizes and resolutions. A touch pad or touch screen can be integrated as an option.