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Is there some standard how the RX and TX cable pairs in a device are connected to a RJ45 ethernet jack?

Clearly I cannot just connect the TX pair of device A with the TX pair of device B. That would only work with a cross cable.

If a ordinary network cable is used, there must be some place where the meaning of RX and TX is swapped. Where is that usually done? Inside the network hub or in the device?

In my case, I'm working on a measurement device that I want to give ethernet access. It should connect to an ethernet hub just like any PC would be connected.

So, should I swap RX and TX pairs inside my device or is that done within the hub?

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    \$\begingroup\$ Nowadays most ethernet interfaces implement Auto MDI-X. \$\endgroup\$ – The Photon Oct 30 '15 at 4:40
  • \$\begingroup\$ @ThePhoton thanks a lot. Just checked the data-sheet of the ethernet transceiver chip that I'm using, and it's doing MDI-X as well. So I don't have to worry at all. :-) \$\endgroup\$ – Nils Pipenbrinck Oct 30 '15 at 4:50
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    \$\begingroup\$ The pin assignment in RJ-45 connected networks is defined in TIA/EIA-568. There is an A and B assignment. \$\endgroup\$ – Paebbels Oct 30 '15 at 6:49
  • \$\begingroup\$ And there is 1000BASE-T were the four pairs are used simultaneously both for TX and RX \$\endgroup\$ – TEMLIB Feb 7 '16 at 1:23
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There are two pin arrangements known as "MDI" and "MDI-X" the convention is that end devices are MDI while hubs and switches are MDI-X.

https://en.wikipedia.org/wiki/Medium-dependent_interface#MDI_vs._MDI-X

However most modern equipment has "AUTO-MDIX" which automatically swaps the transmit and receive pairs if needed so you generally don't have to worry too much about this anymore.

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