The HSLink advantage now applied to improving machine vision


Simultaneously send and receive data with HSLink technology
Pioneered by DALSA Corporation

What is HSLink?
HSLink is a high-speed file transfer protocol which allows a list of files to be sent, over a link, in both directions until each side of the link is satisfied. However, HS/Link is not merely a bi-directional set of rules, it is also a very fast protocol for normal downloading and uploading that incorporates some new technologies to make file transfer more reliable - , the protocol being responsible for protecting the files against corruption during transfer and taking measures to correct any errors that are detected.

How does the new HSLink technology?
The intention of the new protocol is to present a more complete specification for industry's use as the next-generation machine-vision interface.

Designed as an upgrade for CameraLink and incorporating its key concepts, the new protocol enables smaller, lower-cost cameras and frame grabbers, connected over simple network topologies all-the-while considering data reliability as a key design requirement for HSLink development.

Using only a single cable while providing very high camera bandwidths, the new standard offers a low-cost data forwarding mode to reduce image processing costs and user-ease by achieving plug-and-play convenience. Note: HSLink is ideal at any bandwidth because it delivers a small imaging head, reliable and low-cost data transmission technology and ease-of-use with standardised triggering and Genlcam compliance.

Why is HSLink an improvement on the previous standard??
The interface has taken the key strengths of Camera Link™ (an industry-specific connectivity solution), while using broadly-used, off-the-shelf components with development road maps for increased performance. This protocol will have a long service life and is designed to ensure longevity in the marketplace with an expected life cycle 10 - 20 years.

As well, new features and functions have been added to meet customers' present and future needs.

How does HSLink work?
To gain a better understanding of HSLink, Figure 1 provides an overview of HSLink topology from a camera perspective, and Figure 2 provides an overview of HSLink from a framegrabber perspective. Note: the camera perspective and the framegrabber perspective are very similar and use the same technology, the framgrabber using it in reverse order.
The HSLink IP Core takes in Camera Link signals and priority manages trigger, GPIO image data and configuration data and sends this information to the PHY via GMII (Gigabit Media Independent Interface) and/or NBI (Nine Bit Interface). The HSLink IP core ensures guaranteed data delivery and simplifies design implementation in both framegrabbers and cameras.

Multi-vendor PHYs, that operate on NBI and GMII, are available that serialize and de-serialize the data transmitted over the cable medium. For low bandwidth applications (<300Mbytes/s), Infiniband (IBx1) or Coax cabling offers a low cost solution.

For applications up to 2100Mbytes/s, a single CX4 cable is used, which significantly reduces the size and number of cables required compared to today’s machine vision standards, and still delivers 15m transmission distances.
Figure 1: (above) Topology of HSLink from a Camera perspective
Figure 2: Topology of HSLink from a Framegrabber perspective
 

As seen in both diagrams, the HSLink IP Core takes in input signals that the machine vision industry understands from the CameraLink standard.

On the camera side, the HSLink IP Core takes these inputs and sends them via GMII (Gigabit Media Independent Interface) and/ or NBI (Nine Bit Interface), and ensures guaranteed data delivery.

The PHY (SERDES chip) takes the information it receives, serializes it, and transmits it to the framegrabber via cabling.

Depending upon the camera bandwidth the PHY sends the information in three potential formats named by the subcommittee as NBILink, GMIILink and MixedLink. Each format has its own associated cabling and protocol

What are the some of HSLink's features and benefits?
Globally available
•
Off-the-shelf components are used. No license or royalty fees. No chip-supply issues.
Scaleable bandwidth
•
 Scaleable in 300MB/s steps from 300 to 6000 Mbytes/sec, 1x to 20x configurations, while maintaining a common, consistent control interface and ease of implementation.
Camera size
•
 Minimised
Triggering
•
•
 Protocol handles real-time triggering. No need for a separate trigger cable.
Real-time triggering - low jitter of 3.2ns makes HSLink viable for linescan applications
Data transmission
•
 Reliably achieved through redundant trigger codes, hardware resend capabilty (this enables minimal buffer sizes and so no external memory is required), and proven technology.
Plug and Play
•
 Cameras are GenICam™
Video efficiency
•
 HSLink Protocol - exceeding 95% video efficiency.
Lower cabling costs
•
 Having scaleable bandwidth capacity also lowers cabling costs and size as the cable can be selected according to the camera's bandwidth

HSLink comparison with other interfaces
Feature
HSLink
Camera Link
10GigE
GigE
CoaXpress
Bandwidth 6000MB/s 850MB/s 1200MB/s 100MB/s 1.200MB/s
Scalability NBI 1x-300MB/s,
and multiples
GMII/Mixed up to
2100 MB/s in steps of 300MB		 Lite 150MB/s,
Base 255MB/s,
Medium 510MB/s,
Full 680MB/s,
Full 850MB/s+		 4x- 1200
Multiples		 Multiple of
100MB/s with
additional
connector/cable.		 1x -300 MB/s
and multiples of
300 MB/s
Trigger 3.2ns jitter 0 ns jitter 1us IEEE1588
(special hardware
required)		 1us IEEE1588 12ns jitter
Distance 15m on CX4
80m on RG59		 10m 15m-CX4 100m-Cat7 100m- Cat 5e 105 m
Fibre Optic Yes No CX4- Yes Noi No
Number of
Cameras from
1 FG		 8- 1x cameras 2 (4) 2 4 5
High Speed
Camera Control
(CC) Lines		 8 4 0 0 0
Network Support Yes- 64 Cameras No Yes Yes No
Data Forwarding/
Replication		 Mixed and GMII
modes and/or via
Data Replicator		 Via Data
Replicator		 Via Hub and
broadcast
message		 Via Hub and
broadcast
message		 Data Forwarding
via Data
Replicator
Com Channel 300 MB/s 1MB/s 1200MB/s 100MB/s 2.1MB/s
Integrate phy into
FPGA		 Yes Yes Yes, CX4 No No
           

Follow the links below to learn more about specific functionality*
• Cabling - NBI, GMII and MixedLink • Priority Technology • NBI Packet Design • Command Packet
• Transmission distance • Data and Trigger Reliability • Trigger Packet • Idle Set
• The PHY (Serdes) • CRC Calculation • GPIO Packet • System Configurations
• 8b/10b encoding introduction • HSLink – Protocol • Ack/Nack Packet • Data Forwarding
• Kcodes and Message Types • NBI (9- Bit Interface) Protocol • NBI Packet • Intermediary Devices
• HSLink IP Core • GMII Protocol • GMII Video Packet • TERMINOLOGY
*Extracted from DALSA Corporation's white paper: HSLink- A Technical Primer

HSLink is designed from a system point of view, ensuring the ability to create low cost cameras and frame grabbers, while meeting the ease of use, flexibility and data reliability required by end customers.


Adept Electronic Solutions are "The Machine Vision and Imaging Specialists" and distributor of DALSA Machine Vision products in Australia and New Zealand. To find out more about DALSA or any machine vision product please email us at: adept@adept.net.au or call us at Perth (08) 92425411 / Sydney (02) 99792599 / Melbourne (03) 95555621 or use our online contact us page.