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How Does the Advanced Cable Tester v2 Measure DC Resistance, and if Needed, Can I Modify a Test Profile?
Rena Ayeras

Question from the Customer:

I have a question about the measurement results from testing printer cables with the Advanced Cable Tester v2. The cables have adapters for USB Type-C to USB 2.0 Standard-B, which is the profile that I selected for running all the tests.

For example, I tested one cable five times.

  • The first two tests passed.
  • The following three tests failed.

Here is an example of a failed test from that cable:

My question is how can I set the profile settings for more consistent results? What changes are allowed? Here is a summary of my test setup:

I also have a question about the WIRES – GND+SHIELD B-Side Link measurement, which seems to be a sum of the Gnd Pins and SHIELD Pins measurements.

Can you explain how that measurement is taken? On another set of cables, this measurement is another result that can alternate between failed values and pass values. Can I change the test profile specification for that as well?

Response from Technical Support:

Thanks for your question! Looking at your test measurements, it appears the failures for your cables are based on the minimum Rd resistor specification, with some influence from the DC resistance (DCR) values. The profile can be edited, and we will provide guidelines for that process. To help you understand more of the Advanced Cable Tester v2 reports, we will go over how measurements are processed.

How Pins are Measured

Here is diagram that shows what is measured:

There are two measurements, the A-side link and the B-side link.

The dotted red line shows how current flows. For the A-side link, the measurement is the difference between Sense1 and the group of Sense2 + Sense3 + Sense4. This method ensures the wire resistance across the cable is not measured.

The wire resistance is not the sum of the pins. The measurement of all four pins on each side are bussed together, and the wire itself is also measured. Another measurement also includes Shield contact, which may reduce the measured resistance – the reduction would be slight.

The GND+Shield B-side link measurement is similar to the GND+Shield A-Side Link measurement.

DC Resistance Profile

The minimum Rd specification of the USB Type-C to 2.0 Standard-B profile is the cause of failure in the results that you provided. This can be resolved by editing the profile, which is described in the next section.

Editing the DC Resistance of the Profile

Here are the steps to edit the test profile, which you save as a new profile.

  1. In the Advanced Cable Tester v2 GUI, click the Profiles
  2. In the Filter drop down menu, select USB Type-C to USB 2.0 Standard-B.
  3. Click on the corresponding Profile, and then select Copy and Edit.
  4. Go to the DC Resistance section in the Profile template that opens.
  5. You can then edit the min Rd Minimum value of 4845 (downward). If needed, other testing parameters can be edited.
  6. Save the profile.

When you run the next test, choose this new profile you have created.

WIRES – GND+SHIELD Measurement

This test confirms whether a cable complies with the Type-C Specification R2.1, Table 3-12, Note 6:

Shield and GND shall be connected within the USB Type-C and USB 3.1 Standard-A plugs on both ends of the cable assembly. It's mechanically difficult to make this connection in the Standard-A plug, many cables are missing this connection.

To determine compliance, a measurement is taken between the GND and Shield contacts only on the A plug. The threshold for this measurement is (GND Cable + Shield Cable) / 2.

  • If the connection within the A plug is not good, then current has to flow to the C plug and back. This would result in a value similar to GND Cable + Shield Cable.
  • If the connection within the A plug is good, then current will flow only within that plug, and all the wire resistance would be irrelevant. In this case, the value would be far below the threshold.
Note: Our algorithm may not work if the ground or shield resistances are significantly high.

If this measurement does not work for you, you can “deactivate” it by setting the profile option "DCR: Strict GND/Shield Spec Interpretation" to false. As this measurement is complicated, changing values is not supported.

If needed, you could create a custom test profile for your specific test requirements. Here is a video that shows how:

We hope this answers your questions. Additional resources that you may find helpful include the following:

If you want more information, feel free to contact us with your questions, or request a demo that applies to your application.