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ASK THE EXPERTS

Cables / Cable Assemblies / Connectors Questions

Question Asked:

How is data transmitted over camera link affected by using cable lengths longer than the 10 meter limit typically specified? Is it just that the highest frame rates cannot be realized, but lower frame rates are possible? Or is it that the image integrity is compromised?

4 Answers

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  • = Answered Questions

Ron Folkeringa - Business Manager
Intercon 1 - A Division of Nortech Systems, Inc.
rfolkeringa [at] nortechsys [dot] com
(218) 766-9660

Hi Kathy, Cable lengths longer than 10 meters are very possible. It all depends on the Camera Link Mode being used and the pixel clock frequency. Please email me directly with the specifics of the camera and framegramber being used and I can provide more detail as to what can be expected for cable length. Ron Folkeringa Business Manager Intercon 1 rfolkeringa@nortechsys.com www.intercon-1.com

Cliff Hayes - Field Application Engineer
EDT
cliff [at] edt [dot] com
(503) 748-7897

What Ron said is correct. It comes down to pixel clock frequency and how many bits you're sending per clock cycle. Higher clock frequencies and more bits per clock mean the error tolerances need to tighten up or else you'll get corrupted data. Therefore, cables generally get shorter as you go up with Camera Link modes and clock frequencies, however there are higher quality cables and active cables to address that. EDT makes Camera Link to fiber optic converters which can support the full range of Camera Link and get your around any cable length limitation you might come up against.

Thomas Detjen - Head of Sales and Marketing
Alysium-Tech GmbH
t [dot] detjen [at] alysium.com
49 173 5803588

Hi Kathy, i agree with Cliff and Ron. However, the results in the end can differ, depending on the Camera + FG + Cable MFR (!) you have choosen. So, depending on the complete application, with Full Configuration, 10Tab, etc. there are max. - stable - cable length of ~14M possible, in some combination it will end up with much shorter cable length. Of course you can choose also to go with Active cables, which might be solution for your application, but increases mostly some other pain points - and if its only in the overall costs. ;) If you need any further assistants, please feel free to contact us at any time. Thanks, Tom Alysium (td@alysium.com)

Mike Miethig - Technical Manager
Teledyne DALSA
mike [dot] miethig [at] teledyne.com
519-886-6000

Hi Kathy: Camera Link uses a clock (1 differential pair) in parallel with the data (4 LVDS differential pairs). The data bit rate is 7x the clock rate and there is certain phase relationship between clock and data that must be maintained for correct data transfer. The data lines are not DC balanced and so data transmission is a function of the data values. The worst case is sending all 1's or all 0's for a long time and expecting the transision between 1 and zero to be correct. As others have mentioned, distance is a function of camera, framegrabber, cable, bit rate and CL configuration. It should be noted that there is no error detection in camera link. Camera Link HS uses 8b/10b or 64/66b encoding to ensure DC balance and achieves 15 meter on copper cables at 3.125 Gbps per lane. The cable is similar to Camera Link but has 7 down lanes for an effective data bandwidth of 2.1 GByte/sec in a single cable. Bit errors are detected and CLHS is single error immune.

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