Help! What is this stuff?

[dougclind]

I'm trying to take over for someone who abandoned the work. They were attempting to hook up a wifi that would cover a campground and needed about a half mile radius of coverage.

They left me with:
1. a "stick" antenna with an N connector (no problem there, seems ok)
2. something called a "POE", model: UBI-POE-15-8
3. (2) supposedly burnt out BULLET 2HP devices. The box says it has AirOS V 3.3.2

The POE box shows a diagram of how to hook things up: CAT5 from the LAN goes into the LAN port, another cable (presumably a CAT5) goes from the POE port to the BULLET. I presume that the BULLET is supposed to directly connect to the antenna. I hooked everything up that way

When the POE is plugged into the AC, I get a Power Active green lite on the POE. But when I plug in a good LAN cable from my router, the router LAN lite never comes on, indicating to me that the POE is not active. I plug that same cable back into a computer and the router LAN lite comes on.

So the cable is good, the router is good: does this mean that the POE is bad? No LED lights ever come on in the BULLET. The guys who abandoned the project said that the BULLETs were bad. They had 2 of them and lights don't come on in either of them. There's a little reset button on them and I tried pushing that but nothing happens. But still, no light ever comes on on the router for the LAN cable going to the POE.


Even though I'm a degreed electrical engineer, and even though I'm a licensed amateur radio operator, and even though I've worked with configuring routers and working with LAN's (not an expert though!), even though all this, I don't have a clue what these things are and I can't make heads or tails of the Ubiquiti website. And I don't know how to troubleshoot this thing.

Can someone help me out? BTW, I'm not charging the camp for my efforts, just doing it to help them out, no matter how long it takes.

[Dave-D]

No matter how long it takes. What a guy!

Your hookup, if I understand all your steps,
appears OK. Here's a quick review:

A CAT5 cable has 4 pairs of wire; 2 pairs
are used for the Ethernet (network) circuit,
the other two for power to the radio.

The CAT5 cable from the router to the PoE
device carries only the Ethernet circuit. The
PoE unit is called an 'injector'; it contains a
15v power supply. It passes the Ethernet
circuit through to the radio and adds on
('injects') the dc power into the other leads.

The PoE light indicates only that there is
dc power available. Clearly, if you connect
a router to the PoE injector, there is no
Ethernet device--so don't expect an Active
light at your router port.

When you connect the radio to the PoE device
it's powered and becomes an active Ethernet
device. If its power LED doesn't light and there
is no Ethernet activity, there can be one of
three reasons:
> bad cable for either power or Ethernet
> bad PoE power supply (even with a light)
> bad radio--won't power or isn't active.

As a quick check, get a short, known good
Ethernet patch cable and interconnect a
radio and PoE unit. I highly doubt you have
two bad PoE units, so you can swap radios
to verify if either lights up. If not, bad
radios. (You can also check the PoE units
by metering for dc voltage--8-pin jack pins
4 and 5 are positive, 7 and 8 are negative.)

BTW: if you have two bad Bullet radios, I
suspect they were connected to a PoE with
too much voltage. Be sure the PoE devices
you have are rated for 15 to 24V max. The
units you list are 15V types.

Hope you have fun with this. Dave

[tmulkey2]

Those POE ingectors do use the other pairs. They are not 802.3AF POE standard. They inject DC over Wire 45 and 78. So if you have someone who only used pins 12 and 36 on the cable that will work on 802.3AF, because it injects AC on the same pairs the data used, but not on these POE units. I leaned this thinking I was going to use on cat5 run up a building to run two units. SO make sure he ran all 8 wires in the correct order. Another thing you could do it strip the end off a patch cable and see if you are getting 15volts between pin 4+5 and 7+8, out ot the POE side of the incector. and then you could get a 12 volt power souce and try to power the bullet directly as well.

Make sure the POE units are UBNT's units and not a 802.3AF unit. That would cause it as well.

The seem to run okay all the way down to 12 Volts as well, becasue I am working on a solar setup for remote towers where I will have no power source. I am going to put up some SLA Batteries and a couple of Solar pannels.

[Dave-D]

Tmulkey, I have no idea why you
came up with all this 'stuff'. This
is not a discussion of 802.3af,
and that's simply confusing.

He is using Ubiquiti 'ingectors' and
they do use the standard wire pairs. Dave

[CharlesA920]

You have not said that you were able to log into the radio... kind of important so you can configure the unit...

These units have a factory set (and will revert to this when "reset" button is pushed) IP of 192.168.1.20 with a sub net of 255.255.255.0

So go ahead and push the reset button...
hook up the radio to your computer using the PoE
configure the IP on your TCP/IP to anything within the same range as the radio eg. 192.168.1.4 sub net of 255.255.255.0

open a browser and enter the 192.168.1.20 into the address bar and GO
(you're unit must show both the power and LAN lights now or it will not work)

should open a login box... unbt & ubnt

this is where you start... .

EXCEPT it won't work for you if the LAN is out on your unit(s).

[Dave-D]

Doug, how did you make out? Dave

[WHT]

So if you have someone who only used pins 12 and 36 on the cable that will work on 802.3AF, because it injects AC on the same pairs the data used, but not on these POE units. HUH ???????
Poor-man's PoE like the UBNT and many other manufactures' use pairs 4&5 and 7&8 for power, and it may be 12 to 24 volts DC, *AND* the voltages may be reversed. 802.11af uses the same pairs.

[dougclind]

The voltage was good from the POE device, approx 15V. When I connected it to one of the Bullet 2HP devices I got a brief flicker from the power LED. Then nothing.

I'm waiting on getting another Bullet and see what happens.

I contacted the guys who were working on the project before and they said the setup was working fine with a short LAN cable to the POE but when they hooked up a 250' length of outdoor CAT5, the Bullet failed. I tested that same CAT5 cable and it's fine. As a matter of fact it's being used as-is to hook up another building on the camp. The max length of a CAT5 is rated at 100 meters so that shouldn't have been a problem.

Anyway that's when I went ahead and ordered a replacement Bullet. So I'm waiting on getting that and I'll pick up from there.

So I guess this Bullet is just a little 800mW wireless router?

[WHT]

The voltage was good from the POE device, approx 15V. When I connected it to one of the Bullet 2HP devices I got a brief flicker from the power LED. Then nothing. ... The max length of a CAT5 is rated at 100 meters so that shouldn't have been a problem.

Yes and no.

The 100 meter (328 feet) limit is an arbitrary number that was decided on for the distance, it could have just as well been 300 feet or 91.4 meters. That distance is about as far as you can send a signal with acceptable signal quality and keep the cable manufacturing cost down.

But when it comes to PoE, that's a different animal. Especially with non-802.11af 48 volt PoE, such as the 12 volt systems.

From one of my post last year...

When using 12 volts:

Some people have experienced problems with as little as 150 feet run of CAT5.

Most people experience problems past 200 feet with CAT5.

Some people say the thicker gauge CAT6 works. But personally I believe when using the thicker CAT6, the decreased voltage drop will be so small they may not be a significant advantage after you compare the cost of CAT6 versus replacing the 12 volt power supply with a 24 volt one.

Most people run an 18 or 24 volt adapter as a solution.

With the exception of the Bullets' 24 volt max input voltage, all the other radios are 25 volts.

Many people have successfully tested long term use of 24 volts on the Bullet using a good quality power supply.

Almost all wall wart power supplies are switching power supplies now, very rarely will see an analog voltage regulator scheme. That means you have to very very careful when working at the max voltage levels of a device, because a switcher only begins to regulate after it sees the load. That means it can potentially output more than 24 volts for a very brief moment immediately after power is supply to the switchers input.

[dougclind]

WHT, You've got me a little confused here because the 250' of CAT5 was between the router and the POE, not the POE and the Bullet. For the cable between the POE and the Bullet there was only a short, one foot cable.

[Jayson]

WHT - Is 802.11af some new standard. I am familiar with 802.3af.

802.3af can use phantom power on the data pairs. How else would you get POE on 1000Base-T? To be 902.3af compliant a device must be able to take power on pairs 4/5 & 7/8 or 1/2 & 3/6 whether or not they have data on them. So you are correct in that some devices use the spare pairs just like "Poor man's POE" , but they also must be able to take power over the data pairs when connected to a mode A switch/power supply.

[shapiros]

Jayson, you are correct. The IEEE does not "specifically" spell out the "af" extension within 802.11. However, it is widely known and has been adopted as the mechanism for PoE in devices that do not fully comply with 802.3af. I could go into gory details about how 802.3af (mid-span only to operate a wireless device) = 802.11af but a simple google search is better suited.

Also (and I cannot confirm this), but I have heard that there is an effort to incorporate 802.11af into the wireless spec. Thus, making WHT's "poor mans PoE" a standards compliant device... sounds like a price increase to me...

Sig

[WHT]

The 802.1af has pretty much been superseded by 802.11af, so the 802.11af is what you want to be concerned with. When using "poor man's PoE", its more specifically 802.11af's Mode B (not Mode A). Mode B uses the 4&5 and 7&8 pairs for power.

[WHT]

dougclind...

I may not have clearly understood your lengths involved.

What I posted was a generalized preoccupation when using long PoE runs.

[shapiros]

To further WHT's elaboration on PoE (how did this "creep" into this post???)

There have been two traditional means of accomplishing PoE. One is what AIR802® refers to as pre-802.3af compliant PoE (sometimes referred to as 802.3af Mode B), which is less costly to implement and offers other advantages. The second is 802.3af (or 802.3af Mode A) compliant devices at each end of the network cable. These are known as the power sourcing equipment (PSE) and the powered device (PD) in 802.3af terminology. The use of 802.3af Mode A provides interaction between the PSE and PD to turn power on or off, etc., where passive, pre-802.3af, or Mode B technology provides an always on DC voltage (the voltage depends on the input to the injector). Pre-802.3af technology or 802.3af Mode B uses the spare pairs (pins 4,5,7 and 8) of an Ethernet network cable to deliver the DC power. Products using 802.3af may deliver power over pairs one and two (pins 1,2,3 and 6) in what is referred to as mode A. Use of the spare pairs can only be used in 10BASE-T and 100BASE-T networks. A 1000Base-T network uses all four pairs. There are many products in the market that use PoE. Some use passive pre-802.3af (802.3af mode B) and some use 802.3af compliant technology.

cut and pasted from (an excellent elaboration):
https://www.air802.com/passive-power-over-ethernet-poe-injector-splitter-mid-span-kit-p5.html?printable=Y&&cat=0

Sig

[helix247]

May not even be relevant, but i noticed when I tried to upgrade a factory pico to the newest avail. firmware (about 3 weeks ago). I could not get a LAN light either. Only power. When I went back down a notch or two, it came back then I went back and read a few forum post on upgrading (funny how I should have done that first).