Black Box ServSwitch SRX Manual De Usuario

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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: 

•  If a local video monitor is found, its DDC information will be compared to 

the information already stored and, if different, will be copied, stored and 
presented to the video adapter upon request. 

•  If no local video monitor is found, the local module will make available its 

previously stored set of DDC parameters to the video 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 SRX 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.        

When power is first applied to the local module (either from 
the computer’s USB port or an optional power adapter) it will 
search for valid DDC data on its video out connector. During 
this process, the yellow indicator (built into the link connector) 
will flash to indicate its progress:

•  If no valid DDC information is located, the yellow indicator 

will give one very short flash, representing an attempt to 
read data. No changes will be made to the information already stored within 
the local module.

•  If the DDC information is the same as that already stored, no change will be 

made and the yellow indicator will give one single flash as the information is 
checked and normal operation resumes.

•  If different DDC information is located, the yellow indicator will flash rapidly 

for 2 to 3 seconds while the new information is stored. A single flash will 
then be given as the information is checked and normal operation resumes.   

The local module’s yellow indicator also provides fault indications to assist with 
troubleshooting:

•  Two flashes - Checksum error prior to copying - no information will be 

programmed.

•  Three flashes - Too much data to fit into the module - the module can hold a 

maximum of two pages of DDC information.

•  Rapid flashing followed by four flashes - data was lost during copying - the 

default data was substituted. Repeat the power on process.

•  Rapid flashing followed by five flashes - Checksum error during copying 

- the default data was substituted. Repeat the power on process.