Cross-wired Uart Ports between two Pine Boards via Cat5 Cable

[MarkHaysHarris777]

On the female RJ45 jacks mounted in the ABS boxes ( or where ever ) run the wiring from the RJ45 to female connectors for plug-in to the uart(s) on the respective pine boards.

If you're putting RJ-45s on the ends, why not just use or wire them as ordinary Ethernet cables? Then you can use it for ethernet or as an extension for serial... and the only then the difference is the wiring past the RJ45 sockets. I don't see the point in making up special cables when there's actually nothing special about them! :-P

Yes, you're absolutely correct, if you are ever only going to connect just two boxes.  Because Rx-->Tx and Tx-->Rx the cross-over has to occur someplace  1) in box A,  2) in the cable,  or 3) in box B.   If I were just going to connect two boxes the cross-over need not be in the cable.

But I have three boxes. So, I want to be able to use the same cable between any two of the three; so the boxes are wired identically, and the cable has both pairs crossed. But, you're right, this obviously ruins the cat5 cable for ethernet.  

On the other hand , its just a single 2m cable that only has to be modified for the use case once; so, its not too big a deal.  I have cat5 cables laying all over the place here.