Making a USB cable

[kiddagoat]

So I have a question here and this is my thought process....

At work I have a situation where I am trying to replace some serial scan guns and parallel printers with USB equivalents.... problem is that the current conduit in place doesn't allow the play to enable me to run the USB lines through them with the old stuff in place. I cannot pull the old stuff out as the boss man wants to have some sort of contingency should the USB do something weird. The conduit is about 1/2 inch in diameter.

Eventually I can pull the old stuff out once I have a proof of concept that works.

I was thinking about making my own USB cables. Now I know USB has a limitation with only going 5m (18ft) before signal degradation and loss start to take place. I have read that using Cat5e/Cat6 will over come this limitation. My concern is power.

I need the run of cable to be about 20 feet and then the scanner/printer cables are about 6 feet each. I read that if I use a pair from the Ethernet cable cable for D+ and D- that I can use the 3 remaining pairs can be used for VCC and GND. With the VCC lines being in parallel it will have stabilize the power and prevent signal loss.

Any idea? Suggestions??

 

[megaflegmi]

I suggest you try these:

http://www.ebay.com/itm/Extension-U...pter-Extender-Over-Repeater-Set-/181830166675

I have tested such a pair with keyboard and mouse only. Over 40 meters Cat5e LAN cable ... not high quality just common cable, it works OK. Can't tell you if USB will work at full speed. I guess shorter the LAN cable better the USB speed.

 

[taz420nj]

There will be far too much voltage drop for the devices to work reliably more than 15-20 feet without overloading the USB ports - even if you triple up the extra conductors. The USB to Cat5 baluns are a much better way to go, but pretty much all of them are cheap chinese crap, so don't expect any sort of support. The ones you should use would have an external power supply - either injecting stable 5V at the receiver end, or sending 12/24v from the transmitter end and stepping it down to 5V at the receiver end.

Another option would be to actually network the devices on the LAN rather than trying to kludge something together.. Get networkable printers or USB print servers, and there are USB 'device servers' that allow you to network things like scanners/AIO printers, webcams, USB hard drives/flash drives, etc. They might work for your barcode scanners too.

 

[dorsetknob]

http://www.maplin.co.uk/p/usb-20-cat5-extension-kit-a44hg
Supposedly rated to 50m or 160ft
Im sure you can find equivalent from new egg or similer supplier