Note that the TX (transmitter) pins are connected to corresponding RX (receiver) pins, plus to plus and minus to minus. And that you must use a crossover cable to connect units with identical interfaces. If you use a straight-through cable, one of the two units must, in effect, perform the crossover function.Two wire color-code standards apply: EIA/TIA 568A and EIA/TIA 568B.The codes are commonly depicted with RJ-45 jacks as follows: