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A recent addition to available familiar cable testing models such as Permanent Link, Channel and Modular Plug Terminated Link (MPTL) is the Direct Attach Channel, or DAC.  The Direct Attach Channel is designed to provide direct connection between active devices within a data rack environment, without the addition of patching hardware.
(For a Knowledge Base article on MPTL, follow this link: https://www.flukenetworks.com/knowledge-base/dsx-cableanalyzer-series/modular-plug-terminated-link-mptl-test-limits-dsx-5000-and )

Typical applications for DAC are:
  • Switch to server direct connection
  • Switch to storage device directly
  • Switch to switch.

Most applications are likely to be in Data Center or Office environments.
Whilst it is tempting to view the DAC as a potentially very long patchcord, up to 90m long, this is not entirely correct, as authorities have recognised the DAC as a network element in its own right, and provided guidance for their comprehensive testing and certification.
The DAC may not have intermediate connectors, being limited to a single male plug connector at each end, most likely to be of the field-terminatable type to maintain maximum performance.  The DAC is considered a data-transport ‘Channel’, but for correct testing inclusive of the male plugs, a new testing model is required.
The use of the ‘traditional’ Channel model for testing the DAC is not appropriate, as this model specifically excludes the first and last connectors from the test result, and allows for multiple connections within the link.


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As the DAC has only 2 connectors, and it is essential that the performance of those connectors is included in the result, Patch Cord Adapters matching the cabling class must be used.  (Patch cord adapters are unique to the class of cable under test, and are not backward-compatible.)


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The Direct Attach Channel has been standardised by ISO as a Technical Report, reference ISO/IEC TR 11801-9907: 2019, and a full test procedure can be found in ISO/IEC 14763-4.   Within the DSX-5000 and 8000 Test Limit selector, find the DAC under ISO Class EA, Class E or Class D, as shown below (for ISO/Class Ea.)



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As always, contact your warranty provider (if the testing is to support a warranty) to confirm their requirements for certification of this link type.


Equipment required for DAC certification, in addition to DSX-5000 or DSX-8000:

  • DSX-PC5ES Cat5e/Class D Patch Cord Adapter Set for Class D DAC.
  • DSX-PC6S Cat6/Class E Patch Cord Adapter Set for Class E DAC.
  • DSX-PC6AS Cat6A/Class Ea Patch cord Adapter Set for Class Ea DAC.
For any further information regarding Direct Attach Channel testing, please contact your local Technical Assistance Centre.
 
Keywords: DAC, Certification, DSX-5000, DSX-8000