Created Date: June 10,2004

Created by: bcarlton

In a STANDARD Ethernet cable there are 8 wires organized as 4 pairs. In standard communication only 2 of the pairs are used, one for transmit and one for receive. The cable was derived from one already used in telephone communication. It has known impedence and transmission characteristics. Over a VERY SHORT distance you might get just 2 twisted pairs to talk but it's not a good idea. If you wish to DIRECTLY connect two PLC's without the benefit of hubs or switches in between then you must use a crossover cable which swaps the transmit and receive pairs from one end to the other, so that the transmitter on one end is talking to the receiver on the other end. Hubs and switches perform this switch for you and you can use the more common (and less expensive) straight through cables. Of course the hubs and switches have many more important features than just this swap, but it's good to know.

Created Date: June 10,2004

Created by: marksji

If your cable is going to be any significant length (say more than 5 feet) make sure the wire and the ends you put on are certified CAT5. With short cables you can sometimes get away with low quality wire and connectors, but beware that your throughput will drop off and retrys will increase with a bad cable.

I 've used these guys for custom cable lengths and found them to be very reliable. http://www.stonewallcable.com

You can also have them build shielded cables, shielded CAT5 is a big help in electrically noisy situations.

Created Date: September 06,2004

Created by: jfenske

10/100/1000 base T Ethernet Cables (Being either cat 5, 5e, or cat 6 are assembled to standards that encompass the type of wire, twists per inch, shielding or no shielding, impedance and color coding to the rj 45 pinouts. ADC suggests using what is considered the buisness color coding of the wires "Type B " while there is a "Type A " which is exactly the same except they switch a wire pair color. (The cables are actually interchangeable) The vast majority of cat V + cable will have 4 pairs of wires in it. All 10/100 base T switches will be setup for this cable configuration (The majority of 1000 base is still on that configuration). I strongly suggest that you stick to standards on this. If you are trying to steal a pair or two out of the bundle for other uses you are asking for trouble. For the cost of what Cat Ve UTP goes for pull another line. A thousand foot of riser grade goes for about 70 bucks. (The most expensive part of the line is the tool to crimp the rj45 ends on.) If these are long runs it pays for itself very quickly. (I have spent $150 on a single pre made 100ft patch cable in a pinch.) In areas of high emi or rfi use a shielded twisted pair (STP) making sure for grounding considerations to the wire.

There is nothing better than that feeling when you plug it in for the first time and the thing actually works. But there is also nothing more frustrating than a system that on the surface appears to be fine, but once in operation fails spuraticaly and without any apparent reasons. This is especially true of deterministic networks. The only way to avoid this is proper wiring and design, and even then murphy's law still applies ocassionaly.

Good luck