User manual

4 Windows Utility
4.4.4 Device Request
USB devices are naturally only plugged into one slot at a time. Consequently the drivers for USB
devices either control their device, or are not loaded at all. Sometimes they are instructed to
unload, thus allowing to un-plug the device from the computer.
Likewise the USB Server application is based on a single user model, i.e. only one user can access
a USB device at a time. In a multi-user network, multiple PC clients can use the USB devices
connected to a NetUSB-400i USB Server product. These users can connect to USB devices one at
a time only, and users wanting to claim a specific USB device will have to wait for the other user
to relinquish the connection. When a specific USB device is claimed by one user, it gets shown as
Busy to other users on the network.
Imagine a PC client user (call her Alice) wants to connect to a USB device, which is currently
connected by another user (named Bob). Then this device is shown as Busy on the PC of Alice.
Now Alice can issue a Device Request command to Bob’s PC. This feature allows Alice to send a
request to Bob to free the device which he has connected. If Bob accepts the device request, then
the USB Device is available for Alice to use.
The user can request a busy USB device by right clicking on the USB device in the Device Map-
ping window and by selecting the Device Request option in the popup menu. The Device Request
function can also be selected from Device Mapping in the Menu Bar.
Figure 37: DeviceRequest Option
As soon as the Device Request is initiated by the requestor (Alice) an acknowledgment dialog
appears that the request has been sent successfully (figure 38).
Figure 38: DeviceRequest Sent
A Device Free Request message is sent to the user (Bob) currently accessing the USB device, to
intimate that the requestor is willing to access the USB device (figure 39).
Figure 39: DeviceRequest Received
October 2009 NetUSB-400i User Manual 27