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Comment by londons_explore | Hacker News Reader

I really want my computer to have a built in cable tester. Just plug both ends of the same cable into two different ports of a computer, and it has a little popup saying "This cable can support charging at this rate and data at that rate, and is fully functional". Or "This cable has 1 bad pin, and that may affect video/audio/charging/whatever functionality"

Ideally, the computer would test every pin in the cable, and also test the resistance/voltage drop of the cable to detect thinner-than-spec conductors.

I'm pretty sure USB-C hardware in a typical laptop can already do most of this, if only the firmware added support for such testing.

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It's really strange that even getting a separate testing device is really hard. There are some that test pins and some that can read the emarker, but none affordable that can do both.

I'm assuming it would involves more ICs which it can bump the cost of the testing kit exponentially to test all of the pins.

If it's exponential that's a huge assumption that needs more backing.

I'm not a EE. It is my understanding that to fully test 24 pins would includes putting a full load of higher wattage through those wiring to ensure they are capable of transferring. Higher wattage which means it needs a larger transformer to output that large amount of power or it would need a 200+ watts power brick to supply the wattage. That includes needing safety/failsafe components to protect itself and the device it is connected to, thus increasing the risk of potential damage if it was mishandled. I won't be surprised if the cable reporting that it can handle higher wattage when it is not in reality. Also, this includes the testing system to ensure it is handling rigorously without damaging it.

I don't know the cost of the such device, I am assuming the higher cost based on other devices for other thing such as ethernet cable tester such as Fluke which are $100+.

I don't see how testing the wattage would be much different if it was two pins on a barrel plug.

Also you only really need to test the resistance here. Or volts and amps separately.

And I don't know if testing power was even part of the idea or if it was more about doing a signal test.

There isn't a big enough market for it, so any device capable of doing this would be expensive due to lack of economies of scale.

My old motherboard had 2 NICs, and was able to test Ethernet cables this way.

> I really want my computer to have a built in cable tester. Just plug both ends of the same cable into two different ports of a computer … If you have a Mac you might be able to try the Blackmagic Disk Speed Test app. It would require you to also have a drive that* can handle the read/write speeds of the cable you are testing… but you’ll only get accurate numbers if your drive can handle read/write that’s above what the cable can handle. Hopefully someone else knows of a better way.

If the computer could test on a loop like the parent comment suggested, every single machine built in the last decade has enough memory bandwidth to test >40Gbps. No need to write to disk.

Something like this? https://hackaday.com/2023/08/11/usb-c-cable-tester-is-compac... https://www.tindie.com/products/petl/usb-c-cable-tester-c2c-...

No, these only test connectivity. They do not check the eMarker.

Mikrotik routers have something like this for Ethernet cables. They can detect how far down a cable break is and on what twisted pair. (They don't test cable bandwidth though.)

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