Finding which USB cable goes to where

[Spidy (Phil)]

Hi all.


I'm not at home and can't test this theory but I was wondering, with all the USB cables tied together in a typical rig, when you disconnect them is there a way to test which end of a USB cable belongs to the same cable by using a multi-meter to measure conductance by using the external connectors only?


Another way to put this is if I use a multi-meter and place the prongs on the outside of the connectors, are they attached through the length of the cable so the multi-meter will show me the continuity?

[Startrek (Martin)]

Yes in most cases you can use the metal casing of the USB plug to check end to end continuity. The metal casing is connected to a fine braided shielding end to end
A multimeter set to Ohms x100 will go full scale when tested end to end
I just tested a couple of different cables and brands
USB2A male to USB2A male
USB3A to USB3B
USB2A to USB2A female
And so on …….
And all tested fine with a continuity test

In my Obs all my USB cables are labelled, makes life so much easier when replacing or fault finding

Although I suspect some “el cheapo” USB cables may not have a shielding end to end

Cheers
Martin

[chrisp9au (Chris)]

+1 for labelling, both ends!

[AdamJL]

yep. I label them too. Cheap way to do it: piece of paper with your label written (preferably typed/printed). Then sticky tape it vertically along the cable. Takes all of 10mins to do them all for a typical cable run.

[Crater101 (Warren)]

As someone who is new at this, I started labelling things to help me get my mind around what goes where. Pleased to see I'm not the only one.

[ChrisV (Chris)]

Buy a multi pack of different coloured electrical tape. Wrap a small amount around the cable at each end. Easy to match colours!

And the leftover electrical tape is always useful

[Crater101 (Warren)]

Originally Posted by ChrisV

Buy a multi pack of different coloured electrical tape. Wrap a small amount around the cable at each end. Easy to match colours!

And the leftover electrical tape is always useful

Now there's one of those forehead-smack, "why didn't I think of that before" ideas! I am not worthy...

[oska (John)]

Brother (and others) sell printable heat-shrink for their label printers. Over the top surely but a nice neat option

[Spidy (Phil)]

Thank you all for your responses, and yes, I answered my own question when I got home.


Thanks Martin for your detailed response and thanks to the others suggesting I label both ends using the various methods listed below.


On the night, I needed to identify which cable was which. Now that I know the continuity test works, I will definitely find the time to not only label each end of the cable but also the actual USB port that each label is plugged into.


For those curious, my issue was my Celestron focus motor kept disconnecting after a command was sent to it. Turned out when I was cable tying everything together in an effort for some cable management, I plugged the focus motor into the wrong USB port of the Pegasus Power box. I used the USB2 port which did not supply enough voltage/current.