[ideas]

hi guys, need some help with this.
i have a diagram of how to build this cable myself, but am stuck & confused where it says one wire to be connected in N/C.
need your help...
am gonna try attach the diagram  CD-014A.JPG (17.67K)
Number of downloads: 16

[GrofLuigi]

Would N/C mean Not Connected by any chance?

GL

[Tripredacus]

ideas, on 09 July 2012 - 12:26 PM, said:

i have a diagram of how to build this cable myself, but am stuck & confused where it says one wire to be connected in N/C.

From what I can tell is that pin 5 on 6P6C (RJ12) needs to connect to any pin on 8P8C (RJ45) that isn't being used (4, 5, 8).

The N/C means that particular pin does not make a connection to whatever it plugs into. Since it is actually laid out in the diagram that it connects to pin 5 on the other side makes me think it might be used for grounding?

Anyways, this type of cable seems to be fairly inexpensive to buy.

[jaclaz]

N/C is the conventional name for Not Connected.
In this case it means that the RJ45 (that has 8 contacts) is used on a 6 wire cable of which one (the one connected to the Pin #5 on the RJ12) is cut SHORTER than the others and is NOT connected to ANY receptacle on the RJ45 side )or you can use a 5 wire cable, if you find one).

The schematics is evidently drawn by one of those nice guys that like to make things more complex than actually needed .

Usually it is "etiquette" to NEVER change the pin order on either side of a cable schematics.

Here are a couple examples of more "clear" schematics:
http://buzzdavidson.com/?p=24
http://ltxfaq.custhelp.com/app/answers/detail/a_id/328/~/cable-to-connect-a-dec-vt-terminal's-mmj-to-a-lantronix-rj45-serial-port

@Tripredacus, a wire marked N/C must NOT be connected to any pin/receptacle.

jaclaz

[Tripredacus]

jaclaz, on 10 July 2012 - 09:03 AM, said:

@Tripredacus, a wire marked N/C must NOT be connected to any pin/receptacle.

Ok I didn't know about "cutting the wire shorter" before. I suppose it depends entirely on whether or not the thing you are plugging into is also designed to not have a connection at that point as well. I had a certain picture in my head when typing that (ie USB connector block) which has the N/C pin physically removed.

[jaclaz]

Tripredacus, on 11 July 2012 - 09:02 AM, said:

Ok I didn't know about "cutting the wire shorter" before. I suppose it depends entirely on whether or not the thing you are plugging into is also designed to not have a connection at that point as well. I had a certain picture in my head when typing that (ie USB connector block) which has the N/C pin physically removed.

Yep , same happens on RJ connectors, if you remove the "pin", since it is the pin itself that perforates the wire insulation.
Though it is usually quite difficult to remove a single "pin" from a RJ connector.
Point is/was that "better be safe than sorry" unless you know that *nothing* is connected to the pin #5 of the RJ12 receptacle, and besides there is no data to know if the "N/C" wire on the RJ45 receptacle would go on which among pins #4, #5 and #8 (you should remove all three of them, but usually, if on the RJ45 socket there are all 8 contacts, the ones that find the "hole" where the "pin" shoud be won't "like it" much and will tend to bend/stuck the connector ), cutting the cable shorter on the RJ45 side is the faster and safer way.

There is also another (remote) possibility, that on the RJ12 side the pin #5 is connected to a ground of some kind, in which case having a 6 wire cable with one wire connected to pin 5 on the RJ12 side and cut 2 or 3 millimeters shorter on the RJ45 side would provide a form of "shielding".

jaclaz

[ideas]

i made the cable and it works, so the most important thing is to connect the pin 6 to the pin 8 diagram, the additional 3 wires in the pin8 i still them as space holders.
n/c means that the pin 8 does not make contact to the device or not connected

Thanks guys