I'm looking at an application where there is only one avaialble pair of wires through an interface. The wires are in a CAT-5 bundle but only 1 of the twisted pair is avaiable. The length is only about 200 ft.
The desired connetion is ethernet with a laptop on one end and a a piece of ethernet industrial equipment (commanding and data monitoring) on the other. Since it is only a single pair that would ofcourse mandate half duplex operation. 10Mbits would be plenty fast.
Wifi is not possible for this application.
My question is can a standard laptop with a RJ-45 type ethernet connector be setup to use only a single pair if wires in half dulex mode? Google turned up nothing for me.
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Long-Reach Ethernet provides an extension to the IEEE
802.3-compliant Ethernet standard network. LRE extends Ethernet over single-pair wiring at distances of up to
5,000 feet. Cisco LRE technology combines simple and standards-based LAN connectivity and extension over existing telephone wiring, while boasting several competitive advantages. The Cisco LRE technology provides a point-to-point link that can deliver half- or full-duplex Ethernet at up to a 15-Mbps data rate
I can't see why it shouldn't work. I've certainly managed to get 100Mb half- duplex operation by accident when debugging Ethernet (KS8993/5) designs. I expect all switches do autonegotiation now. But if you're worried, it's easy to try out- just take an ordinary Windows network, sacrifice a $2 cable by cutting one active pair, and see if you can connect up.
Yup. If you've got $600 to spend, you're done, golden. Can reach a lot longer than 200ft, as well. Old, slow, seems to be obsoleted, Tut Systems. New, faster, made in USA, buy off the shelf, B&B Electronics.
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Just a happy customer with 1200 feet of single twisted pair (Cat3, yet). Getting 40MB on the B&B equipment, which replaced the older Tut equipment that could only do 2MB over the same wire.
If that runs outside, spend a few more bucks on lightning suppression at both ends.
Practically speaking, a reel of 1000 feet of ethernet cable is a lot cheaper, and will run your distance 5 times...ISTR that the Homely Despot even has 500 foot boxes.
The oldest, cruftiest of tricks is a pair of baluns and a
10base2 (thinwire) media for your link. This will require a powered adapter box to serve a modern (10/100 or 10/100/1000 unshielded twisted pair) Ethernet jack. I'm not sure how the terminator current sensing was handled, there may have been some DC feedthrough added to the balun.
The modern way to do it on the cheap is to retask two pairs in the CAT-5 for Ethernet and put a hub in so your distant computer doesn't hog the connection. Then you have to replace one of the cable's functional pairs with an Ethernet service of some sort.
There are lots of DSL 'last-mile' solutions too, but those, and the Cisco and BlackBox solutions might be priced for industrial users.
There's only a 200 foot distance, eh? Have you considered WiFi with aimed antennas?
There are a few SDSL modems which can theoretically can be used back to back.
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Similar prices to the extenders that Ecnerwal mentioned, SDSL modems might be cheaper in quantity. SDSL might work (at lowish speed) on longer cables than the extenders, though irrelervant to the original question from Mook.
I don't think this is easily possible with the sort of ADSL modems usually used for home internet connections. I suspect that at minimum it would require serious firmware changes and the different upstream and downstream frequencys would be a big problem.
I think we have seen all the good answers to this now. I can think of a few other random ideas, like modifying "homeplug" style network-over-mains-wiring devices or linking 900MHz wifi equipment using the twisted pair instead of through the air.
Thats what I'm going to try. Just looking for someone that understands the hardware details of ethernet to know if this is something that will work or is doomed to failure.
The key points are that we don't want to do anything external to the network cards in the laptop and the test equipment. We just want to hook a cable with 1 twisted pair to the the TX and RX pins (I'd guess you'd short them like rs485) on the ethernet ports on both ends and have it work.
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