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Comment by bravura | Hacker News Reader

Can you recommend a reliable cable tester?

Real cable testers are specialized high speed scopes with all sorts of protocol support and cost thousands.

But what you need is a device that simply queries the cable and asks it what it thinks it can do. I haven’t seen one for sale and am too busy to make one, but it shouldn’t be that hard.

Apple’s system info ought to tell you this but doesn’t.

Thousands? You're about 1-2 orders of magnitude low...

Thousands sounds about right to me. For example the only one I've played with is $15k (Advanced Cable Tester by Total Phase).

I wish, I've looked a little but part of the problem is the new specs. I doubt many testers can be "forward compatible" to be able to test new specs before they exist. I have an old USB-A tester I used but it's obviously useless for USB-C and all it's specs. Even then, the old tester I have just tells you the speed/wattage, not the max, it's more for monitoring than testing.

At some point I'll just have to bite the bullet and get whatever is on the market and hope there aren't new specs right around the corner.

I believe Totalphase tests signal integrity instead of specifically what kind of cable it is - which solves the forward compatibility problem but their stuff is very expensive for the home user

You can get little USB power meters but they only tell you voltage and current, not transfer capability. Actual cable testers cost thousands.

>Actual cable testers cost thousands.

Why? Surely there could be some SBC or something for like $100 which you could connect to your computer. The testing software can measure how long it takes to transfer a file. Then it could try charging itself from the computer requesting a higher and higher wattage. I don't see how a device like that could be so expensive.

So that measures transfer speeds, but what about the rest of the things USB carries?

Here's an example of the data that cable testers can give you: https://m.youtube.com/watch?v=XFbJD6RE4EY

The goal is to determine the type of cable. Testing the signal quality is an entirely different thing.

Yeah, I would like a test device that could let me know which transfer rates a cable supports. I've got a huge pile of USBC cables (and adapters). A good chunk of them might even be USB 2.0!

It seems like a device capable of acting as a host & device could just try to shove data down a cable and see what the max is...

On the Mac, there's a simple way to check cables:

Take a USB3 device, plug it in with the cable, and then go to System Profiler (Apple Menu -> About this Mac -> System Profiler). Look for the device, and check the speed. If it says 480MB/s it's a USB 2 cable, if it says 5GB/s, 10GB/s or 20GB/s then it's a USB3 cable.

I assume there's a way to do the same thing on Windows and Linux.

I just tested that, and it works. Using a Samsung T7 SSD. Clever. Now I wonder if a similar trick works for power capabilities?

There's $50-200USD USB PD meters on AliExpress. I like Ruideng / RD-Tech brand ones.

Coconut battery shows how much power your battery is charging with. I've only used this to compare power supplies, but I don't see why it shouldn't work with cables as well. Of course that only works when the battery is empty enough to actually fast charge.

It would be helpful if the connectors for the different cables had different shapes, so it would be immediately obvious what kind of cable it is and mostly prevent plugging incompatible cables into the wrong places. Thank you for listening to my TED talk.

Thanks to "helpful" legislation, everything must use the same port. Expect this to only make the situation worse in the coming years.

I mean sure, but you can't see signal quality at 1gb/s without a scope capable of much higher rates (you need at least a few points in each period). Short of muxing together several fpgas and hand picking components, you straight up can't see the signals. There's a reason why you can buy a 4 digit multimeter for $30, 5 for maybe $500, and >5 costs thousands.

What do you want to test? Another reply has mentioned the 15K USD TotalPhase device, which I'd love to use one day.

For "home" testing, I've used a USB C -> NVMe enclosure (UGreen is my favourite) with a half decent NVMe drive in it. Does the drive reach 1 gigabyte / second sustained read/write? Congrats, the cable supports 10 gigabit.

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