BECKHOFF CP-Link3 - Manual (Page 7)

Page 7
Functioning
Ethernet-based desktop transfer software
On the one hand, CP-Link 3 transmits the screen content of a host PC over Ethernet to one or more Panel PCs, known
as the CP-Link 3 clients. On the other hand, mouse and keyboard inputs made on the clients are transmitted to the host
PC. The mouse and keyboard inputs from individual clients can be locked, automatically or manually, by the TwinCAT
PLC through a software interface (ADS), so that multiple users do not get in each other's way. Economical standard
Ethernet cables (CAT 5), or Ethernet cables suitable for use in drag chains, can be used to network the devices together.
The scope of delivery for CP-Link 3 includes host and client software. Either Windows 7, Windows XP or Windows XP
Embedded can be installed as the operating system on the host PC. Panel PCs with Windows CE are used as the
clients. Only one CP-Link 3 license is required for each host PC, regardless of the number of clients.
Virtual-USB
USB devices that are connected to a client appear to the host PC as locally connected devices, and can be used in the
usual way. In this way, the keyboard input, touch screen and special key functions of a client are transmitted to the host
PC. It is also possible for USB sticks, USB printers or USB bar code scanners to be connected to a client and used by
the host PC. “Virtual USB” emulates a USB root hub in the host PC. If a USB device is plugged to the client, then 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. As communication takes place using 100 Mbit/s Ethernet,
the USB 2.0 transmission performance (480 Mbit/s) is restricted.
Communication with the connected USB devices takes place through a normal TCP/IP connection. It is therefore not
possible to guarantee that these devices are queried with a deterministic cycle time. When additional input or output
devices, such as rotary switches, keys and so on, are used on the client it is sometimes necessary for a specific cycle
time to be observed. As an alternative, communication with such devices can take place through an additional
BECKHOFF CP-Link 3: Product overview