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ServSwitch Wizard VGA/USB
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3.3 Video display (DDC) information
The Display Data Channel (or DDC) is an industry standard scheme which allows video monitors to declare their capabilities to the
computer’s video adapter circuitry, allowing the latter to optimise their outputs accordingly. Since the widespread adoption of the
scheme, video adapters have become increasingly dependent on receiving relevant DDC information during startup, before they
will output anything more than a rudimentary video signal.
It is not possible to transmit DDC data back from the video monitor that is attached to the remote module to the computer’s
video adapter. Therefore, during startup of the local module, it will search for a video monitor connected to its local feed-through
connector:
• Ifalocalvideomonitorisfound,itsDDCinformationwillbecomparedtotheinformationalreadystoredand,ifdifferent,will
be copied, stored and presented to the video adapter upon request.
• Ifnolocalvideomonitorisfound,thelocalmodulewillmakeavailableitspreviouslystoredsetofDDCparameterstothevideo
adapter upon request; or, if none were stored, a default set.
In either case, the DDC information taken by the video adapter will be used to determine the video output that is sent via the
ServSwitch Wizard VGA-USB modules to the remote monitor.
If you find that the default DDC information is not completely suitable for your remote monitor, try temporarily connecting your
remote monitor to the video out port of the local module. When the local module is powered up, it will read and store the DDC
information from your monitor. You can then return the monitor to its remote position and the new DDC information will be used
at every power on.