User guide
3
Video support
AdderLink XD522 works hard to transfer the highest possible video bandwidth
between the transmitter and receiver units. To allow for the differing grades
of CATx links used to join the transmitter and receiver, AdderLink XD522
periodically checks the quality of link A (the primary cable joining the transmitter
and receiver). In this way it can accurately determine which of two video transfer
modes can be supported. Please see Tips for achieving good quality links for
further information. Please also see Tested video resolutions.
On the front panel, the HR indicator will illuminate when High Rate mode is
available, whereupon the second video port is enabled and the total available
bandwidth for video signals is more than doubled.
The manner in which bandwidth is made available to the two video ports differs
between the Low and High Rate modes, as described here:
EDID management
AdderLink XD522 intelligently manages the EDID (Extended Display Identification
Data) information that each video display provides (detailing their supported
resolutions) before reporting them to the host PC. In this way AdderLink XD522
can mask the resolution modes that cannot be supported within the available
bandwidth. The display attached to Video port 1 will always be given priority.
If sufficient bandwidth does not exist for the modes declared by the second
display, then it will not be reported to the host PC. Please see Appendix B for
details about how the EDID details supplied by each display are managed.
High rate mode
This diagram indicates how the total bandwidth of the high rate mode can be shared
between the two video ports.
Video port 1 (which has priority) may take up 280 MegaPixels per second (of the total 308 Mpix/sec
bandwidth); while port 2 can use a maximum of 154 MPix/sec (subject to port 1 using no more than
154 MPix/sec of the available total bandwidth).
For example:
A single WQXGA
mode display could
consume nearly
all of the port 1
bandwidth alone,
or...
... two WUXGA
mode displays could
share the total
evenly.
Note: The example modes shown here are for illustrative purposes and are based
upon average requirements for current video displays. Video displays from some
manufacturers may consume more signal bandwidth than those shown here.
* All approximate video mode bandwidth figures are quoted with reduced
blanking.
During low rate mode, the secondary video
port is disabled and a total bandwidth of 148.5
MegaPixels per second is made available to the
primary video port. This is more than enough to
support a single 1080P video display.
Low rate mode