Re: RJ-48 Polarity

Hi Bob...

Now-a-days, tip/ring polarity probably doesn't really matter as far as
making services work. But at all my buildings (16 of them with several
hundred DS-0 & DS-1s) I stress that it's important to keep tips and rings
straight (that means tip conductors always connect to tip conductors and
ring conductors always connect to ring conductors). In fact, I get my nose
more than a little bit out of joint if I find things wired otherwise.
Finding some MixMaster mess of wiring tells me the tech didn't understand
what was being connected - he (or she) just started messing around with the
interface until things started working. This reminds me of what an old line
Bell System tech told me once: "Two wires - hoook 'em up; four wires -
fxxx 'em up!" All that applies to tips and rings.

Transmit and receive pairs can sometimes be rolled, however. It depends
upon the application, of course. If you're extending services from an
outside carrier, for example, transmits should be connected to transmits and
receives to receives (that is 1-2 to 1-2 and 4-5 to 4-5). But if you're
connecting a "DCE" to another "DCE" - as in the case you cite - then you'll
probably have to connect a transmit to a receive, that is 1-2 to 4-5). Does
that make any sense? (Dang! I didn't think it would!)

Maybe this will help:
Extending a carrier's demark to a DCE type CPE: 1 to 1, 2 to 2, 4 to 4 and
5 to 5 (a "straight through" connection)
Connecting two local interfaces together: 1 to 5, 2 to 4, 4 to 2 and 5 to 1
(a "rolled" connection)
(Notice above that the tips always connect to tips and rings always connect
to rings).

I've found that if you draw a picture of it on a piece of paper it's easier
to make it work once you get the wires and tools in your hands! Less
frustrating, too! AND... Your boss will be pleased with your
"documentation"!

Good luck!

Al

"Bob Simon" <bsimon@xxxxxxxxx> wrote in message
news:r3lfu1hnqr51oqm6aortsvbtcuhpe6jilg@xxxxxxxxxx
I'm connecting two PBX ISDN interfaces together. The following are
the signal definitions for RJ-48:

1 Receive (ring)
2 Receive (tip)
4 Transmit (ring)
5 Transmit (tip)

I used trial and error to get transmit and receive properly crossed
between the two T1 cards. I'd like to know if there's any reason to
be concerned about polarity within a single signal pair. ie 1-4 vs
1-5, etc.

If polarity does not matter in this application, does it ever matter
in telecom applications?


.

Relevant Pages

  • Re: RJ-48 Polarity
    ... tip/ring polarity probably doesn't really matter as far as ... ring conductors always connect to ring conductors). ... Transmit and receive pairs can sometimes be rolled, ...
    (comp.dcom.telecom.tech)
  • Re: RJ-48 Polarity
    ... If you swap Tip and Ring, the pulses are inverted, but it doesn't matter. ... Transmit (ring) ... I'd like to know if there's any reason to ...
    (comp.dcom.telecom.tech)
  • RJ-48 Polarity
    ... the signal definitions for RJ-48: ... Transmit (ring) ... If polarity does not matter in this application, ...
    (comp.dcom.telecom.tech)
  • Re: RJ-48 Polarity
    ... I guess maybe I over stated the insensitivity to polarity! ... ring conductors always connect to ring conductors). ... All that applies to tips and rings. ... Transmit and receive pairs can sometimes be rolled, ...
    (comp.dcom.telecom.tech)
  • Re: telephone wire polarity
    ... :>>>> coming into the house and they are split to most locations. ... :>>>> When I used my telephone polarity tester, ... And see if the "meter" tells you it's okay. ... The ring generators are current limited, but can still supply enough current to damage the heart or brain if it should flow through them. ...
    (alt.home.repair)
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