Wired, outdoor PC cameras?

[Ken Blake]

I had never heard of 568A or 568B before. Short of taking it apart, is it possible to tell which connector it is?

[Scott Lurndal]

It's the same connector (RJ-45) for both. 568A/568B are the standards for which wire goes to which contact in the (usually) female connector.

Cables (with male connectors) are typically wired straight through or crossover (rare now).

[Ken Blake]

Yes, I know. I guess my question wasn't clear.

Yes, I understood that from Char's post,

I thought (especially for crossover cable) that it was especially pertinent to male connectors.

Yes, I know. What I didn't know was that a crossover cable is one that is connected 568A at one end and 568B at the other. I was asking whether (and if so, how) I could tell whether the connections were

568A or 568B. I basically wanted to know that so I could tell whether an old cable I might have lying around is a crossover cable.

[Carlos E.R.]

I have one such cable. It is perfect. it is used for temporary connection to my laptop, and being able to pull it off easily is a plus :-D

[Scott Lurndal]

[Scott Lurndal]

You can (a) look at the wire colors in the cable through the transparent connector and match them to the chart, or (b) plug the cable into a cat5 cable tester.

Assuming that whomever made the connector followed the wiring T568 suggestions.

[Paul]

Ohmmeter.

Check whether 1,2 on one end, goes to 1,2 on the other end. Or, whether 1,2 on one end, goes to 3,6 on the other end.

The first is straight thru.

The second is crossover.

Of the eight wires (four twisted pairs), four of the wires are "legacy" material. 1,2 and 3,6 pairs were used on 10/100BT for the wiring. The remaining wires would not be doing anything.

On the legacy stuff, a TX pair was wired to an RX pair. An RX pair was wires to a TX pair. That was the four wires.

Whereas GbE is bidirectional on eight wires total.

And the waveform on GbE is "beautiful". It's PAM5. It would look even nicer, if we could see the PAM5 eye diagram on the Tektronix digital scope. Very colorful.

( )

Paul

[Ken Blake]

Actually, a few minutes ago, I looked the one cable that I could easily find. Yes the connector was transparent and yes I could see that they were the same so it wasn't a crossover cable.

But are the connectors always transparent? My memory might be wrong, but I didn't think so.

[Ken Blake]

Thanks, but I don't think I need to do that. See the other reply I'm about to send.

[Ken Blake]

My memory is apparently wrong. It just occurred to me that it would be very easy to look at the cables coming into my router.

Yes, the ends of all four of those connectors are *all* transparent. What must have confused me is the part of the connector next to that end transparent part is opaque, colored the same as the cable itself.

[Char Jackson]

Ugh! Just do a visual check. Put the two cable ends side by side. If the colors match, pin for pin, it's straight through. If not, it's most likely a crossover, but could also be miswired (not likely). You can use the colored pictures found online, as well.

[Char Jackson]

AKA 8p8c

Agreed.

Not sure what you're saying there. Gender has nothing to do with it. The two wiring standards (568A & 568B) apply equally to both genders, although patch panels, which are almost always female, are normally wired straight. The crossover role, if needed, is normally left for the patch cable, the link between the patch panel and the piece of equipment.

Right, using either 568A or 568B cable/pin assignment.

Agreed.

[Scott Lurndal]

You ought to see the eye diagram for 400Gbe and 800Gbe with PAM4.

[Clare Snyder]

99.999% of cables in the last 15? or more years are straight throgh cables since the advent of automatic switches which are "cable agnostic"

[Clare Snyder]

You use a cable tester

[Clare Snyder]

At the price of the cable ends and the likelihood of having to use 2 before you get it right - compared to the cost of cheap chinese cables with the ends molded on, replacing patch cables becomes a no-brainer. It's not like we are paying $18 for a 3 foot patch cable any more - -

- -

[Clare Snyder]

All crimp cable enda are transparent. I'd say 90+% of molded cables are also transparent. I can't remember seeing one that was not.

[Clare Snyder]

When I was tasked with re-wiring the insurance office when we moved in (brand new building which had been wired for the previous tennant who went bankrupt before opening - and the creditors cut off the server-end cables) - I found about half of the premices wiring was wired 568A and half 568B - and I had to trace each cable back to the server cabinet, identify it, deternine how it was wired, and re-terminate it. I went through a LOT of cable ends as I found the simplest way to determine was to wire them all as A, the rewire them if they ended up being B. Ends up part of the building was wired by one contractor and part by another and after I figured out which wiring was done by which it started going a bit easier. 256 drops in all - 128 for data and 128 for voice (phone) - and they were all cut off 3 feet from the 10 foot ceiling. I ended up installing the patch panels in a rack above the door in the server room - so all the work was done on a stepladder. After that was all done came the renovations, where we converted a small theatre room to workstations - with a cable trench serving 18 workstations requiring about 3 Km of CAT5E cable and about the same amount of #12 THWN. That project kept me occupied full time for almost 3 months - - -

[micky]

In case of a police raid you can quickly break the connection.

Monoprice is a good place to buy cables.

It used to have incredibly cheap prices on batteries, labeled with their own name, a couple years ago, but last night I checked and they don't sell them at all anymore!

[micky]

You don't have to know which format they are to know if they are crossover. Hold both ends next to each other and see if the colors are in the same order. If they're not, it's crossover. If they are, it's not.