5250 cabling weirdness

[NeXT]

I'm running a twinax cable from my 5394 controller in the computer to a terminal in my bedroom. It consists of a 25' cable, a male/male coupling and a 5' cable. The terminal can't talk to the controller.

I separately tested each cable and the coupling and there are no breaks or shorts. The only weird thing I find is that when all three components are connected together the two twinax pins reverse which is completely impossible from what my testing had found.

Even with different cables it will reverse. WTF?

 

[g4ugm]

That's what one would expect with a straight through coupler that's the same sex at both ends. If you look at the coupler from one side then you are looking at the front of the nearest connector.
However if you could see through the nearest connector you would see the BACK of the far connect. So it must have been turned through 180 degrees so its pin 2 is now on the other side.

It shouldn't matter as Twinax is a balanced system...

 

[NeXT]

Correct you are. I rekeyed the male/male adapter so the cables on either side were rotated 180 degrees from eachother and like magic the terminal was now talking to the controller.


OOps...

 

[g4ugm]

Glad you are sorted. Been there a long time ago with RJ45 on flat cable need to flip for straight through. However I didn't expect twinax to care. I have learnt something as well.