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I stopped trusting USB-C cable labels and started testing them

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Re: I stopped trusting USB-C cable labels and started testing them

#231

Earlier quoted context omitted.

> Can you imagine a what would have happened if the car charging infrastructure would have used your regular 120/230V plugs? They largely do. I’m not sure I understand your point? The amount of current pulled by the car in an EV is dictated by the car (equivalent to the PD controller on USB-C) and the amount of current max is indicated by the EVSE (which, is sort of like an emarker). When you plug that EVSE into the…

"absolutely nothing" is overly strong wording for a plug-in EVSE. The standardization of the receptacles tells how much current is safe to pull. "This receptacle is 50A rated and can supply 40A continuous" is given by the 14-50 receptacle shape.

But you can buy an EVSE capable of pulling 40 amps and plug it into a 20A rated receptacle. It will happily pull 40 amps until the breaker pops. Most EVSEs that are plug in have adapters to do explicitly this purpose.

Re: I stopped trusting USB-C cable labels and started testing them

#232

> But I shouldn't have had to do any of this. It's time cables came with a label of their own, or some sort of color coding. There shouldn't even need to be a label. A USB-C cable should be a USB-C cable should be a USB-C cable. There should be a single connectivity/performance spec, and if the cable meets it, it can be called a USB-C cable, and if it doesn't, it should have to be marketed as USB-JUNK or something. T…

USB-C is literally just the name of the connector. USB-A can also have varying speeds across it... and B. These are all connectors, not speed ratings.

There is usb 1, 2, 3, and 4 that are more of a statement on the performance capability.

Re: I stopped trusting USB-C cable labels and started testing them

#233
post #165

I coded this as an exercise https://apps.apple.com/app/cable-detective/id6765963737?mt=1... - reads everything it can about the plugged in cables and devices, feeds it to Apples internal AI. In the latest version it even doesn't crash the computer anymore after rapid plug/unplugging action.

There are several apps that do something similar and the biggest issue is the marker on the chip it's interrogating doesn't guarantee the cable can actually provide that. The maker can program whatever they want into that chip and the devices will just negotiate and determine what they're actually capable of achieving anyways.

Re: I stopped trusting USB-C cable labels and started testing them

#234
post #141

Earlier quoted context omitted.

At $150 (“on sale” from $184?), wonder how close it comes: https://anker.com/products/a2687-anker-prime-charger-160w-3-...

I have not managed to stress test it yet, I believe that so far I saw it deliver ~100W max. I got it for 110€ in some Amazon bundle together with 3 usb cables. Which is about the price of the 140W Apple brick. (We don't get the powerbricks included with the MacBooks.) But Apple's is much larger, heavier and has a single port.

Anker did a great job with their image comparing it to the Apple charger. Gave me a good sense of size and wattage.

And it’s much lighter? Nice, wishlist!

Re: I stopped trusting USB-C cable labels and started testing them

#235
post #84

Earlier quoted context omitted.

Okay, great, it’s called USB-D. Is this a new connector? Or do we now need to resort to labeling cables and checking the label? Do we do this for every new version and combination of versions for USB? USB-PD? Thunderbolt? DisplayPort?

> Or do we now need to resort to labeling cables and checking the label? YES oh please yes! Give me labels! I'm sick of playing guessing games with my USB cables. Which one should I use for my external drive? This cable is thick! Will it work? Maybe it's only thick so it can send power? It seems impossible to tell, even if I plug it in to my computer. The files are there, I just need to somehow guess that it's a bit…

Color coding seems good

Re: I stopped trusting USB-C cable labels and started testing them

#236

Earlier quoted context omitted.

Time sampling isn’t enough. You need to at least look at waveform integrity (which can be approximated, by doing things like looking for harmonics). For example, you may send in a 40 GHz square wave, and get back a wave full of ringing, or a sine or sawtooth wave. It’s damn difficult to maintain clean square waves, at that frequency. The cable could also double as a microwave antenna. Since it’s digital information,…

That's not really what I mean. You don't have to diagnose the signal, just the medium, which can tell you what will happen to the real signal. It requires a fast edge (or a very broadband sweep), but nothing much beyond that. E.g., here's what a bad connector at the far end of an SFF-8654 cable looks like on a TDR: https://i.imgur.com/AiLnSuC.jpeg . This type of plot can be interpreted as impedance versus distance al…

Fair 'nuff.

As long as we don't get false positives. They are worse than false negatives, and is what happens, when you just read the markers from the chip. As we know well, lots of dodgy C.M.O.T. Dibbler-types will deliberately program the chips to emit bogus markers.

Re: I stopped trusting USB-C cable labels and started testing them

#237

Earlier quoted context omitted.

Yes. This is the worst case scenario: You don't have the required cable. In an alternative world with no unified connector, you also likely don't have the required cable. The result is the same. It's just that in this world, the worst case scenario happens a lot less. There is often a fallback when you don't have the required cable and you get some functionality. But, most people most of the time the cable they have…

In the alternative world I use the cable that came with the device and I can tell apart from the other 10 black cables.

You can still use the cable that came with the device. Are there a lot of manufacturers who are shipping cables that are not sufficient for their device?

And if the complaint is that cables are the same color, can they not be labeled? Everyone who wants different cables should just treat their USB-C cables as different cables. They get everything they want and the people who want the benefits of mixing cables (at the cost of them sometimes not working) can get what they want.

Re: I stopped trusting USB-C cable labels and started testing them

#238

Earlier quoted context omitted.

But for bandwidth can't you just have two simple computers at either end that can send a 100GB file and if it arrives in 20 seconds, you know you have 40gbps of bandwidth?

> But for bandwidth can't you just have two simple computers at either end that can send a 100GB file and if it arrives in 20 seconds, you know you have 40gbps of bandwidth? Because that is not reproducible and introduces all sorts of other random variables to your test. Expensive equipment is the only answer here. Its a bit like when you ask an electrician to install network cable (yuk !). They consider their job do…

You mention a Fluke, which I'm assuming is in relation to an ethernet cable tester (made by Fluke). I've seen/used continuity testers, but not something better (I've been using iperf3) Could you link/include the sku/model number of what you are refering too?

Re: I stopped trusting USB-C cable labels and started testing them

#239

Earlier quoted context omitted.

> But for bandwidth can't you just have two simple computers at either end that can send a 100GB file and if it arrives in 20 seconds, you know you have 40gbps of bandwidth? Because that is not reproducible and introduces all sorts of other random variables to your test. Expensive equipment is the only answer here. Its a bit like when you ask an electrician to install network cable (yuk !). They consider their job do…

You mention a Fluke, which I'm assuming is in relation to an ethernet cable tester (made by Fluke). I've seen/used continuity testers, but not something better (I've been using iperf3) Could you link/include the sku/model number of what you are refering too?

https://www.homedepot.com/pep/Fluke-Networks-LIQ-100-LinkIQ-...

Only $2,500!

Re: I stopped trusting USB-C cable labels and started testing them

#240

Earlier quoted context omitted.

Why not just USB-C Type 123? That allows for 999 possible permutations of usb-c cables.

because USB-C is a shorthand for USB Type C

So? Is there a hard limit on just one “Type” in the formal name?
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