Camera Link HS
What is Camera Link HS?
Camera Link High Speed (CLHS) is a camera interface standard. First designed as a competitor to Camera Link, HS Link is now administered by the AIA (Automated Imaging Association).
Camera Link HS is NOT backwards compatible with Camera Link.
What is the difference between Camera Link and Camera Link High Speed (CLHS)
Machine vision truly started in the 1950's when two-dimensional imaging for statistical pattern recognition was developed. Over the next 20 years researchers and educational institutes began to employ "vision" to real world tasks such as edge detection and segmentation, which today are considered low-level vision applications. In 1984 an association was formed for the machine vision industry, AIA. Created to support the advancement and understanding in the use of imaging and vision technologies and drive global expansion through education and promotion this association also tackled the challenge of standardization in the industry. As the industry grew it became apparent that camera and Frame grabber manufacturers needed to standardize on interfaces for the industry to truly grow into the future.
In October of 2000 a group of camera and frame grabber manufacturers; including Dalsa, Bitflow, Pulnix, National Instruments and Cognex created an ad hoc Camera Link Committee and published the first CameraLink Standards.
Since 2000 several other machine vision "Standards" were published including GigE, USB and CoaXpress. Camera Link technology continued to improve with Camera Link HS introduced in 2012. So how is Camera Link HS different from Camera Link? The short answer is Camera link sends serialized data streams plus a parallel clock using LVDS. Camera Link HS is a packet-based data delivery process and offers higher link speed up to 3.125 Gb/s (Gigabits per second) and can push the signal length further, 300 MB/s at 10m over copper and up to 1200 MB/s at 10,000m over fiber. Camera Link HS also offers data integrity (CRC, resend) that Camera Link does not. The below chart details the difference between the most popular interfaces for industrial cameras:
|
USB3.0 |
CoaXPress |
GigE Vision 1.x |
GigE Vision 2.x |
Camera Link |
Camera Link HS |
| Single-Link Speed |
5 Gb/s |
6.25 Gb/s |
1 Gb/s |
Up to 10 Gb/s |
2 Gb/s (Base, 1 cable) |
3.125 Gb/s |
|---|
| Maximum Speed |
5 Gb/s |
N * 6.25 Gb/s (N cables) |
2 Gb/s (LAG) |
20/40 Gb/s (2/4 LAG) |
5.5 Gb/s (Deca, 2 cables) |
2N * 3.125 Gb/s (N cables) |
| Complexity |
Medium |
Low |
High |
High |
Low |
Medium |
|---|
| Cabling |
Complex, mass-produced |
Coaxial |
Cat-6 |
Cat-6, optical fiber |
Custom multi-core |
CX-4 |
| Maximum Length |
3m |
100m/50m |
100m |
Fiber 20 km+ |
10m/7m |
15m, fiber 300m+ |
|---|
| Data Integrity |
CRC |
CRC, 8B/10B |
CRC, 8B/10B, Resend |
CRC, 8B/10B or 64B/66B, Resend |
None |
CRC, Resend |
| Real Time Trigger |
No |
Yes, ±4 ns |
No |
Yes, based on IEEE1588 (>25ns) |
Yes |
No |
Table from Xilinx White Paper 453
Camera Link HS offers high bandwidth to support real time control for reliable and error-free operation. Using off the shelf transmission technology including CX4 and SFP/SFP+ fiber-optic components, Camera Link HS may be easier and less expensive to integrate over a GigE Vision system. The standard also supports real-time triggering with latency at 100 to 300 ns and as noted above high reliability.
So, to summarize; Camera Link HS offers:
- Scalable Bandwidths from 300 to 16,000 MB/s
- Extremely reliable data delivery
- Copper of Fiber Optic cables from 15 to 300+ meters in length
- Multi-Vendor compliant components
- IP Cores for Quick, low cost development
Camera Link HS is designed from a system point of view and ensures that CMOS technology can be fully exploited and provides low cost cameras and frame grabbers that offer ease of use, flexibility and data reliability. Find the right camera link HS product for you
How to interface with Camera Link HS
The SFP/SFP+ connector and the SFF-8470 connector (Infiniband or CX4)
Camera Link HS has two standardized connectors. The Small Form-factor Pluggable connector offers 300 MB/s over fiber optical cable over 300 meters, while the SFP+ connector offers up to 1200 MB/s over the same distance. CX4/Infiniband connectors over copper C2 cables offer 2100/3300 MB/s with a 15/5 meter distance.Up to 8 cables are allowed, showcasing CLHS's ability for parallel processing