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Lightwave Communications USB SERVERSWITCH
Page 6 of 25 December 2001
2.0 USB ServerSwitch - System Information
2.1 Video
The USB ServerSwitch incorporates an active, high-bandwidth switch for graphics
adapter cards supporting resolutions up to 1600 x 1200 pixels. The system
supports DDC2B video records, and maintains a local copy of the video record for
each attached server (after a proper power-up sequence). A constant impedance
of 75 ohms is maintained on all video lines in the USBSS, so that the video signal
is not compromised by mismatched impedance. Monitor sense lines are also
transported by the USB ServerSwitch. The ID lines are buffered and passed from
the monitor to the attached graphics adapters in the servers.
Note: The USB ServerSwitch's USB interface is for discrete USB mice and
keyboards only, and will not support Monitors with USB-provided video controls.
DDC2B Support
The DDC2B video record is generated during the power-up of the system, and is
generated by each server that supports or requires the video record, or else
defaults to a generic VGA mode. The USBSS stores a copy of the DDC2B record
at each Server port, and when that server is switched to the User, that video record
information will be sent to the monitor for a proper video signal.
The video record is determined upon power-up of the system by checking the
video signal with the monitor connected to the User A port, and then the User B
port. If monitors are changed at a later date, it may be necessary to shut down the
USB ServerSwitch and/or the servers to regenerate the proper DDC2B record.
If using DDC2B, it is recommended that both User A and User B have similar video
monitors at their stations, since the DDC2B only supports one video record per
server.
2.2 Keyboard / Mouse
The USB ServerSwitch is an intelligent USB switch for the keyboard and mouse.
Each port emulates the keyboard and mouse fully, allowing an attached server or
PC to boot without having been previously selected. Power for each connected
device is monitored from the USB port.
Note: The USB ServerSwitch's keyboard and mouse interface is for discrete USB
mice and keyboards. It does not support graphics tablets, scanners, modems,
drives, hubs or other composite USB devices. Each USB-A receptacle on the
USBSS will support one USB mouse or USB keyboard.
If there is no connection on a USB server port, a status message "Inactive port" will
be displayed on the front panel display. The other attached servers are not
affected because of the keyboard and mouse emulation.
Each port maintains a local copy of the keyboard and mouse configuration. USB
Port numeration is maintained even when the user has de-selected a port. When