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Power-over-USB/CAT5...what's the longest distance?

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wahnula

Technical User
Jun 26, 2005
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Hello,

Our small company just bought one of these against my advice. I wanted a payclock that ran its software on the server over CAT5, not a USB-powered box that runs on a client. Oh well.

I immediately noticed what the boss didn't, that if the Payclock PC Is farther than 15' away from the terminal, then he would need one of these at 1/2 the price of the paycolck unit itself! $150 for a USB-to-Ethernet adapter??? And seven to 10 days wait, to boot.

I found a substitute adapter that was less that 1/5 the cost, except...it does not work with a 100' cat5 cable. The clock lights up, acts as if it's going to work, then the action of clocking in/out shuts the machine down and causes a reboot. There is no option for an AC adapter/batteries for the payclock.

Since the payclock is USB-powered, length of cable must be an issue as it works fine with those adapters and a 10' CAT5 cable. My question: How to find the right cat5 cable length, trial & error or math? I believe that USB provides +5V and +3V, how long (common sense) before that power becomes inadequate over Cat5 cable? It's a standard Cat5 UTP 24AWG Patch Cable.

The PC we are trying to get to is about 25' straight line, but I don't want to go under the trailer (er, office) with the cable, I would like it visible for inspection. Perhaps a 50' Cat5 would work...any ideas (seat-of the-pants guesses are fine) on the maximum run? Your guess will be better than mine!!!

Thanks wireheads!

Tony

Users helping Users...
 
Update...

Trial & error shows it works fine with a 50' cable, guess we will have to make do with that. Any other ideas are always welcomed.

Tony

Users helping Users...
 
You could try a powered USB hub at the clock end.

The answer is "42"
 
Going by your postings,it appears your going gigabit speed or better asd as such:
50 Feet works as it is the max length for the speed your using between the clock and the cpu,using the type of cable you are using.


Has been in the cabling business for about twenty years and is now the Sr PM for a cabling company located in the Los Angeles area.
Also a General Class Amatuer Radio Operator.
 
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