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#cable#cables#usb#https#com#test#tester#linux#need#whatcable
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Discussion (51 Comments)Read Original on HackerNews
Not reproducible and introduces all sorts of other random variables to your test (buffering etc.).
I have a basket with a lot of USB-c cables and without the tester I can't remember (nor guess) which one does what.
> Cable history
> Add a cable, give it a name, and WhatCable records how it performs over time, with a verdict per cable.
And I have nothing to gain from that sale.
Oh god not again... before everyone starts naming their favourite brand, here's a 265 comment HN thread[1] (from last week !) on why these cheap USB-cable "testers" are not worth anything.
TL;DR You need a six-figure wallet to seriously call anything a "hardware tester" for USB cables. User ChrisMarshallNY has a one-liner summary buried in that thread:
If you only paid $40 for a black-box on your favourite online marketplace, then what you've got is definitively NOT a USB-cable tester.[1] https://news.ycombinator.com/item?id=49152255
But as was repeated 101 times on that thread ....
All that those cheap $40 boxes are doing IS reading the marker.
Sadly you are kidding yourself if you think a $40 box off Amazon is doing any sort of "verification". Let alone in any sort of calibrated, reproducible sense free of random unknown variables.
The $40 black-boxes do two things:
There is zero chance that a $40 black-box, even if it did a naïve packet pushing test, would deliver you reproducible results and introduces all sorts of other random variables."Excessive retries" sounds like exactly the sort of intermittent, hard-to-diagnose cable issues that you will not find unless you test the USB cable on a 6-figure rig. :)
Sadly yes.
Like many people on that thread concluded:
The best "middle ground" thing you can do is pay a premium to buy your cables from reputable manufacturers.
See the discusison linked to.
Trust me, my interest was piqued by that thread and I went down the rabbit warren with Mr Google and spent far too much time on the subject. I looked at the various manufacturers and the setups required.
TL;DR: To start with, you need fancy harness assemblies. Then you need to plug those harnesses into very, very expensive equipment.
You're not going to find anything for $20k. High-throughput USB-cable testing simply can't be done the same way copper CAT6 certification can with a 20k Fluke.
For those who want to play with Mr Google, some manufacturers from my notes: Wilder Technologies, Allion, Keysight, Tektronix, Teledyne LeCroy
Here's one blog post I uncovered during my researches: https://www.keysight.com/blogs/en/tech/bench/2023/02/17/powe...
The only wrinkles for me are that Macs apparently don't interrogate cables when they don't have to, i.e., when the power adapter supplies <= 60W (not sure if that's a USB-C protocol or an Apple implementation limitation) and that the website copy is full of GPT-isms, which makes me suspect that some of the output might be assumed instead of empirically validated as well.
https://github.com/nedrichards/whatcable-linux
But (hazard guess) it comes with a headless CLI binary (no GUI libraries needed) so probably could be ported to Linux (easily with an LLM?)
https://github.com/darrylmorley/whatcable
As I understand it, Windows doesn't expose the necessary low-level hardware information for something like this to be possible.
I have a handful of wireless keyboards that just absolutely refuse to negotiate for charging with certain cables at all, so I'm hoping this will help me at least figure out what those keyboards are looking for in terms of cable.
I have so many cables I've accumulated over the years, I should either purge or at least categorize the functionality of each.
But it is the second product I tried; the first one didn't work (it's a 2020 Stellantis car). So, YMMV.
https://a.co/d/0d9EOGRW
Does require a bit of setup, can scan reviews to see if people have optimized a config for your specific vehicle
It turns out some ethernet cables are missing wires - and capped at 100Mbps! Wait what? I didn't even know that was a thing. I don't know where I got the wire, but into the trash it goes.
What's less easy to replace are all these damn USB-C devices lacking the UFP-identifying circuitry that only work on USB-A chargers using A-to-C cables...
Incidentally — I spent an inordinate amount of time searching for USB3.2 cables on Amazon, and the vast majority of cables were actually just USB2.0 cables with PD support, and not actual Full-Featured cables.
These tools read a chip called an "eMarker". These eMarkers are programmed to say whatever the manufacturer wants them to say - there's no requirement that the information be based in reality. Plenty of cables have eMarkers that claim "40Gbps" or whatever speeds, or support 240W PD...but absolutely cannot deliver either of those. And none of these consumer level software or hardware testers can actually test either of those claims. They can only take the cable's own claims at face value.
Resistance measurements can cursorily test claims of 240W but resistance changes with temperature which changes with current...so unless your tester puts 5 amps down the wire for 5 minutes and then tests resistance it's not a very good test. AFAIK none of the testers flow 5 amps through the cable.
Actual maximum data throughput is very hard to know. The only way to really "know" how much data can flow through a cable is with an expensive oscilloscope or cable tester. Because 80Gbps cables run at ~13GHz, at minimum you need a 26GHz scope (Nyquist–Shannon sampling theorem) or more practically a 52GHz scope. And it turns out it's really expensive to measure electrical signals 52 billion times per second. The necessary devices start at $15,000 (cable signal integrity tester) [0] on the very low end and only work for max 10Gbps USB 3.2 cables, or past $270,000 for 80Gbps USB4 cables (proper 60GHz oscilloscope) [1].
On the high end, each signal integrity test device can actually cost $1-2 million [2] where the base unit starts at $670,000 plus then spending additional money for hardware-accelerated analysis, specialized active probes, and the specific PAM-3 / USB4 compliance software packages.
0: https://www.totalphase.com/products/advanced-cable-tester-v2...
1: https://www.edn.com/12-bit-oscilloscope-operates-up-to-65-gh...
2: https://www.eevblog.com/forum/testgear/uxr1104a-infiniium-ux...
Couldn't you just do a data transfer test over the cable and check the error rate? At least in theory, the controller might not report enough I guess.
IT interconnect closet vs. air vehicle.
For example, I don't need to precisely measure exactly how messed up the signal is to know if the HDMI cable works or not at a given resolution. I'll see the TV have issues displaying a picture. Either the picture is there reliably or its not. I'm not trying to fine tune the cable, I'm just trying to see if it generally works or not.
As for testing power delivery, its not that electrically complicated to put a few amps through a wire for a few minutes. That said, the user must be aware if the cable isn't up to the standards that the chip states you could have some serious issues on your hands, but I guess better to find out on the tester at the workbench or desk than at your bedside.