Fluke DSX-600 CableAnalyzer User manual

Copper Cabling
Troubleshooting Handbook

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Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Why the need for advanced diagnostics? . . . . . . . . . . . . . . . . . 4
Troubleshooting Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Before you begin testing, you should verify the basics . . . . . . . . . . . 5
Link models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Permanent Link . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
The automated DSX-600 diagnostics. . . . . . . . . . . . . . . . . . . . .9
Shield Integrity Test . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
HDTDR diagnostics. . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
HDTDX diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Causes of Cabling Faults . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Wiremap. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Length. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Delay/Skew . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Insertion Loss (Attenuation) . . . . . . . . . . . . . . . . . . . . . . . 19
NEXT and PSNEXT . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Return Loss . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
ACR-F and PS ACR-F (older names: ELFEXT and PSELFEXT) . . . . . . . . 22
Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Architects, Consultants and Designers pages . . . . . . . . . . . . . . . 23
Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
CableAnalyzer Comparison Guide . . . . . . . . . . . . . . . . . . . . . 26

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“Certication” is the process of comparing the transmission performance of an
installed cabling system to a standard using a dened method of measuring the
performance. Certication of the cabling system demonstrates component quality
and installation workmanship. It is typically a requirement to obtain the cabling
manufacturer’s warranty. Certication demands that the cabling links yield a “Passing”
result. Technicians must diagnose the failing links and after a corrective action has
been implemented they must retest to ensure the link meets the required transmission
performance. The total time to certify an installation does not only include making the
certication measurements but also documentation and troubleshooting.
Today’s cabling installation professionals must therefore know how to troubleshoot and
diagnose high-performance cabling systems.
Why the need for advanced diagnostics?
As newer high-performance cabling systems have been developed and deployed, every
aspect of the installation demands a higher level of skill and more attention to detail.
New test parameters have been added. The links must be tested using one of two link
models, the Permanent Link or the Channel and the links are tested and evaluated
over a greater frequency range and with more data points. The components with which
these links are constructed need to deliver better performance and the quality of the
workmanship during installation must rise accordingly.
Due to the increased complexity of these cabling systems, determining the cause of
failure and quickly restoring suitable performance has become a challenging task.
This handbook guides you through the troubleshooting of advanced structured cabling
systems using the Fluke Networks DSX-600 CableAnalyzer™ so you can increase your
productivity and deliver better value to your organization.
Most common causes of failures in twisted pair cabling:
Introduction

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1. Installation errors: failure to make proper connections while maintaining the wire
pairs and the twist rate in each pair (always keep the “original twist” in each wire
pair as much as practical)
2.Connectors that do not meet the required transmission quality
3.Incorrect tester set up
4.Defects or damage in the installed cable
5.Bad patch cords*
* Patch cords rate high on the list when we are discussing operating networks.
Certication is often executed using the Permanent Link Model since the actual patch
cords used by the operating network are not yet installed or available.
Before you begin testing, you should verify the basics:
• Has the correct test standard been selected? The certication test is executed as
an automated test or an “Autotest”. The test standard you select for an autotest
determines the link model (Permanent Link or Channel), the test parameters to
be measured and the frequency range over which the tests are executed and the
Pass/Fail criteria for each test.
• Has the correct link model been selected?
• Are you using the appropriate test adapter with a plug that matches the jack in the
telecommunication outlet (TO) or the patch panel?
• Has the test reference been set in the last 30 days? It is recommended to set the
reference on a regular basis and at a time that is easy to remember. (Such as at the
beginning of each testing session)
• Are you using the most current version of the tester software?
• Is the NVP set correctly for the cable under test? NVP plays a role when the tester
reports length or distance to a defect
• Is the tester within its operating temperature range and in calibration?
Remember that your Fluke Networks DSX-600 CableAnalyzer™ is a very accurate
instrument that measures small noise disturbances in cables. These instruments are
calibrated in the factory before shipping and this calibration should be veried every
12 months in an authorized Service Center. If the tester has been stored in a colder
or warmer place than the one in which you are working (i.e. overnight in a vehicle),
allow the unit to warm up to its steady-state operating temperature before setting
a reference or executing any measurements. This may take 10 to 15 minutes or more
depending on the temperature differential.
Troubleshooting Basics

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The maximum allowed length of the Permanent Link is 90 meters. This link is most
often used by installers to prove the xed portion of the cabling system (excluding
user cords) meets the requirements of ANSI/TIA/EIA-568 or ISO/IEC 11801. The cabling
vendor offering the warranty will require this. If you see an installer making these
measurements using Channel adapters, you may wish to stop them and ask why they are
not making Permanent Link measurements.
Figure 1
To obtain meaningful results, it is essential to select the appropriate autotest and link
model.
Permanent Link
The Permanent Link performance is dened in such a way that after adding good patch
cords to a passing link, the channel performance is automatically met. By good patch
cords, we mean patch cords that pass the same class or category rating as the link or a
higher level of performance.
For this reason, it is recommended that new cabling installations are certied using
the Permanent Link model and test standard. Patch cords and equipment cords may be
changed many times during the life of the permanent link.
Link models

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The Permanent Link shown in Figure 1 includes an optional Consolidation Point. Other
Permanent Link models may have a second patch panel instead of the TO which is
typically seen in a Data Center. The Permanent Link measurement includes the RJ45
plug at the end of the test lead, but does not include the cable portion of the test lead
or connection to the test equipment (See Figure 1). In the case of the DSX Permanent
Link adapters, the RJ45 plug is guaranteed to meet the NEXT, FEXT and Return Loss
requirements of the earlier mentioned standards. The cable portion of the test lead is
removed from the measurement using calibration constants stored in the adapter.
Another Permanent Link conguration that’s being seen more often nowadays is the
Modied Permanent Link. This is not recognized in TIA or ISO/IEC, but is supported in
ANSI/BICSI-004. The Modied Permanent Link is used to asses a horizontal link that
results in a direct connection to equipment like a PoE (Power over Ethernet) Wireless
Access point or CCTV camera. To assess this type of link the TIA Permanent Link test limit
must be used. The main tester must be connected via a Permanent Link adapter to the
patch panel. A Channel adapter on the remote unit at the remote end must be used to
connect the RJ45 plug of the direct connection.

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Figure 2
Channel
Channel measurements are typically performed when restoring a service or to verify the
existing cabling for application support. The maximum length allowed for a Channel
is 100 meters. It is uncommon to perform Channel tests at the conclusion of a new
installation, since the patch cords that belong to each link are rarely available at that
time. Correct Channel measurements must cancel the effects of the mated connection
in the tester’s channel adapters as seen in Figure 2, which also shows the optional
consolidation point we saw in the Permanent Link. The same Data Center and Direct
equipment links also exist for the Channel.

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When an Autotest fails or delivers a “marginal” pass result, the DSX-600 can use its
diagnostic capabilities to nd the cause of the marginal failures.
First, let us review what a marginal test is. The margin of a test is the difference between
the measured value and the applicable Pass/Fail limit value. The margin is positive when
the test passes, negative when the measurement fails and zero when the measured value
is equal to the limit value. A greater margin indicates that the result is further away
from the limit line. A larger positive margin therefore indicates a better test result. A
very small margin means that the test result is close to the limit value. A test result is
called marginal when its margin is less than the accuracy specication of the instrument
for the test parameter. For example, in gure 3, the Return Loss accuracy is +/- 1.79
dB @ 22.5 MHz and the worst case margin of a link at 22.5MHz was 0.4 dB. This Return
Loss result at 22.5 MHz is considered very close to the limit and is called a marginal test
result. A marginal PASS is indicated by PASS*. In this situation, the tester can be set
up to perform HDTDR and HDTDX tests showing diagnostics information to help identify
and point out what may have caused this marginal result. This information provides
the opportunity to quickly locate the problem, correct it, and deliver a link with good
performance. For more information, see the section that discusses HDTDR and HDTDX
diagnostics.
Figure 3
Shows result for worst pair where
the screen has been zoomed to show
the result in more detail. For this TIA
Cat 5e Permanent. Link Return Loss
accuracy is +/- 1.79 dB @ 22.5 MHz.
The margin was 0.4 dB so the result
has fallen within the accuracy band
and therefore is marked PASS*
The automated DSX-600 diagnostics

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Figure 4
Shows a wire map failure on wires 6
and 7. Both are open at 1.4 m from
the near end and 4.7 m from the
far end, suggesting the cable has
been severed or not connected at
the same points. Inspect the link at
these points to identify the issue.
If the cabling link fails to pass the wire map test - the test which veries that all 8
wires connect the right pins at either end of the cable - the tester halts and presents a
window saying ‘Warning Bad Wire Map”. If you press OK, then the wire map diagram is
shown with the option to turn ‘SCAN ON’ which may help nd intermittent connection,
or ‘FIX LATER’ which enables you to save the results then go to then next link to be
tested. Alternatively, you can ‘CONTINUE’ which continues the test with the bad wire
map, this may allow you to nd other issues to help you troubleshoot the problem in the
link. Figure 4 shows such a wire map failure. The DSX-600 main unit is always assumed
at the left hand side of these screens, i.e. the near end. The wire map diagram shows
Wire 6 of pair 3/6 and Wire 7 of pair 7/8, both are open at 1.4 Meters at the near end
and 4.7 Meters from the far end. The software halts and asks the operator whether or
not to continue the test. It often makes more sense to tackle the wire map error before
continuing the test. The open wire causes the results for some test parameters to fail. In
this case we continued and the DSX shows a FAIL. At this point we could inspect the link
at 1.4M from the near end to discover the cause of the failure. We could also select the
DIAGNOSTICS tab which enables us to see the results of the HDTDR or HDTDX results.