49 Spyder2 User’s Manual
03-032-10091-06 Teledyne DALSA
Appendix A
Camera Link™ Reference
Camera Link is a communication interface for vision applications.
For years, the scientific and industrial digital video market has lacked a standard method
of communication. Both frame grabbers and camera manufacturers developed products
with different connectors, making cable production difficult for manufacturers and very
confusing for consumers. A connectivity standard between digital cameras and frame
grabber s i s l ong overdue and w i l l become even more necessary as data r ates continue to
increase.
Increasingly diverse cameras and advanced signal and data transmissi ons have made a
connectivity standard like Camera Link a necessity. The Camera Link interface will
reduce support time, as well as the cost of that support. The standard cable will be able to
handle the increased signal speeds, and the cable assembly w i l l allow customer s to red uce
their costs through volume pricing.
LVDS Technical Description
Low Voltage Differential Signaling (LVDS) is a high-speed, l ow -pow er gener al pur pose
interface standard. The standard, known as ANSI/ TIA/ EIA-644, w as approved in M arch
1996. LVDS uses differential signaling, with a nominal signal swing of 350mV differential.
The low signal swing decreases rise and fall times to achieve a theoretical maxi mum
transmission rate of 1.923 Gbps into a l oss-less medium. The low signal swing also means
that the standard is not dependent on a particular supply voltage. LVDS uses current-
mode drivers, which limit power consumption. The differential signals are immune to ±1
V common volt noise.
Camera Signal Requirements
This section provides definitions for the signals used in the Camera Link interface. The
standard Camera Link cable provides camera control signals, serial communication, and
video data.
Video Data
The Channel Link technology is integral to the transmission of video data. Image data and
image enable signals are transmitted on the Channel Link bus. Four enable signals are
defined as:
• FVAL—Frame Valid (FVAL) is defined HIGH for valid lines.
• LVAL—Line Valid (LVAL) is defined HIGH for valid pixels.
• DVAL—Data Valid (DVAL) is defined HIGH when data is valid.
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