POE Options - POE Smart - Cable Shorts
Posted: Sat Nov 07, 2015 1:08 pm
A typical question new users ask all the time wrote: I have a new NETONIX switch on the table.
I have it ready to deploy…study as much as possible on the forum…BUT I still do not understand exactly what does this warning means PLEASE DO NOT COLD DEAD SHORT TEST THE POE ESPECIALLY AT 48V….“? Could you please explain more simple what should I not do?
This would mean short a cable with POE turned on, since these switches are designed to deliver HIGH current at 55C the Polyfuse will not trip (open) before it damages the Ethernet Transformer in the switch killing the port.
Always make sure to do cable diagnostics on new cable runs and make sure there are no “Cross-Short” detected.
Some devices will report a "Short" on some pairs such as UBNT airMAX M Series 10/100 devices will report a Short on pair 3 and 4 but this is not a "cross-short" and is normal for them.
Also do NOT select 24VH to power a 24V device, it will fry the device and the port.
24VH supplies power on all 4 pair which is needed for long cable runs (over 200 feet) on airFIBER X units but will damage normal 24V Rockets, Nanostations, and similar devices.
48VH supplies power on all 4 pair which is needed to power airFIBER 24 and airFIBER 5 units but will damage devices that only want power on pairs 3 & 4 such as Titanium Rockets or IP Phones and camera.
48VH is also used if powering a WS-6-MIN switch, MIMOSA B5, B5C, and other high power devices from many manufacturers. Always take time to verify a device polarity pin out and voltage requirements before using 48VH.
Some devices will not pass the POE Smart check and require you to turn it OFF for that port on the Ports Tab under the column "PS"
Some MIMOSA and Cambium radios require you to disable POE Smart function to power them.
WARNING - A LOT OF CAMBIUM DEVICES ARE REVERSE POLARITY MAKE SURE TO CAREFULLY VERIFY POLARITY PINOUT AND VOLTAGES BEFORE YOU USE THESE RADIOS WITH OUR SWITCH.
An example of a Cambium device that works with our switch is the ePMP 1000 GPS sync but may require POE Smart to be disabled.
If you disable POE Smart on a port make sure to check for “Cross Shorts” with the cable diagnostic feature BEFORE you apply power.
There are 4 pairs in an Ethernet Cable:
Pair 1: Orange & Orange White
Pair 2: Green & Green White
Pair 3: Blue & Blue White
Pair 4: Brown & Brown White
For a standard 10/100 24V passive device such as a Rocket M5 Pair 1 & 2 carry the communications and pair 3 carries POSITIVE and pair 4 carries NEGATIVE.
For a standard 100/1000 48V passive device such as VOIP phones, Cameras, Titanium Rocket M5 Pair 1, 2, 3, & 4 carry the communications and pair 3 carries POSITIVE and Pair 4 carries NEGATIVE.
You can also power "Active" POE devices such as an IP Phone or camera with "Passive" 48V.
When you talk about 24VH and 48VH the switch is delivering power on all 4 pairs and if the device is not designed to get power on all 4 pairs you will fry the device and the port in the switch. THIS TYPE OF DAMAGE IS NOT COVERED UNDER WARRANTY.
Examples of devices that would use 48VH:
Ubiquiti airFIBER 24
Ubiquiti airFIBER 5
MIMOSA B5 ad B5C
Netonix WS-6-MINI
Examples of devices that would use 24VH:
Ubiquiti AF2X on cable runs longer than 160' other wise you can also use normal 24V
Ubiquiti AF3X on cable runs longer than 160' other wise you can also use normal 24V
Ubiquiti AF5X on cable runs longer than 160' other wise you can also use normal 24V
To date the Ubiquiti AFX product line and Ignite Metrolink are the only devices on the market that use 24VH
NOTE: All new AFX radios now also support 48V and 48VH which is the preferred POE method.
Also Ignite MetroLink radios can use 24VH
Examples of devices that use standard passive 24V:
Ubiquiti airMAX devices such as NanoStations, Rockets, NanoBeams, NanoBridges
Examples of devices that use standard passive 48V:
Ubiquiti Titanium airMAX Rocket devices
MIMIOS B5-Lite
Cambium ePMP 1000 GPS Sync - ALWAYS BE CAREFUL WITH CAMBIUM DEVICES AS SOME MODELS HAVE REVERSE POLARITY
IP Phones - 802.3af/at device
Cameras - 802.3af/at device
COMMON QUESTIONS:
Question: Can I power 802.3af/at devices such as cameras and phones with Netonix Switches?
Answer: YES, but since they are a "passive" POE switch you will have to manually turn on POE for the port. Most 802.3af/at devices use 48V NOT 48VH. Never use 48VH until you verify your device will accept power on all 4 pairs.
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Question: I see a cross-short, is that bad?
Answer: YES, never turn POE on any port where you see a cross short as that means 1 wire from one pair is shorted to another wire of another pair which is a DEAD SHORT and will fry the switch port. Cross-Short is about the only real bad situation that will surely fry a port.
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Question: Why do I see abnormal termination when I do a cable diagnostics?
Answer: Because every manufacturer does not follow the proper design specs so when the device is unpowered it is actually doing the cable test into the device electronics and every device will report differently. They "should" report OK, OK , OK , OK once the device is powered up however some Ethernet surge protectors will always report abnormal termination.
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Question: Why do I see short on pairs 3 and 4 on a of devices especially UBNT airMAX 10/100 gear.
Answer: Because every manufacturer does not follow the proper design specs and use a 4 channel Ethernet Transformer designed for POE with a center tab for each pair. Since pair 3 and 4 is not needed to carry data with 10/100 only links they use them for power only which allows them to use a cheaper 2 channel transformer without a center tap for pairs 1 and 2. They then connect the 2 wires from each pair to the board skipping the need for a transformer with a center tap so the 2 wires from pair 3 are connected directly to the board shorted together for positive and the 2 wires from pair 4 are shorted together directly on the board for negative.
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Question: Why do you say "DO NOT PLUG CABLES INTO LIVE POE PORTS".
Answer: Our switches are "passive" POE which means if POE is enabled on a port the power is live so if you plug in a cable that is shorted or the piece of equipment is bad you will damage the port in the switch and this damage is not covered under warranty.
You own the switch, you can power it up under water if you want to but do not expect that to be covered under warranty same as
shorted ports are NOT covered under warranty
.
Look, to be able to deliver .75A and 1.5A @ 55C we have to size the Polyfuse to not trip while delivering those watts at that temperature which means if the switch is in an environment that is less than 55C the Polyfuse will not trip until way beyond that level. The Polyfuses are used more for fire protection from the result of a dead short and since you can not find Ethernet Transformers to handle more than 1A per pair this means that the chances are extremely high that plugging in a shorted cable or bad device to a live port will result in the damaging of the port and it will cost you money.
You can not compare our switches to "active" POE switches which means that power is applied once the switch negotiates with the device and at that point the switch knows the cabling is not shorted and applies power. The problem with "active" POE switches is 802.3af limits you to 15W and 802.3at limits you to 25W which will not power things like airFIBER radios or deliver 1.5A to a MINI switch.
I have been a WISP for over 20 years now and I KNOW that we all make mistakes and crimp ends wrong from time to time and we are sometimes in a rush and plug the connectors in without being careful they are straight.
If you turn POE on after you plug in the cable the switch will attempt to determine if there is a cross-short and prevent you from making a mistake if you leave POE SMART enabled. POE SMART is not perfect but it catches 99% of the problems and saves a lot of switch ports.
If you turn the POE on after you plug the cable in the connector is firmly seated and straight with no chance of crossing pins and shorting out your port and possibly damaging your device.
Also there is a possibility that when you plug in a shorted cable or one with a bad device that too much power is drawn and can cause your switch to not only damage a port but reboot the switch causing your tower to go down while the reboot is in progress.
Plug a shorted cable into our switch and MOST times you fry that port and the rest of the switch is fine and will continue to operate. Do that to a ToughSWITCH and most times the whole switch ios dead, at least that has been my experience at my WISP over the years. Feel free to try it yourself.
If you want to plug cables into live ports it is your switch do as you want as this damage is easy to spot when you RMA it and we will not fix it for free.
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Question: Can I power this device with Netonix.
Answer: Our switches are "passive" POE which means if POE is enabled on a port the power is live so if you plug in a cable that is shorted or the piece of equipment is bad or has an incompatible polarity PIN OUT you will damage the port in the switch and probably the equipment, this damage is not covered under warranty.
There are 4 Pairs and 8 PINs in an Ethernet Cable:
Pair 1: White Orange.(PIN 1 ) & Orange.(PIN 2) is POSITIVE
Pair 2: White Green...(PIN 3) & Green...(PIN 6) is NEGATIVE
Pair 3: White Blue.....(PIN 4) & Blue.....(PIN 5) is POSITIVE
Pair 4: White Brown..(PIN 7) & Brown...(PIN 8) is NEGATIVE
24V POE Option @ .75A - constant draw can surge/spike to 1A:
802.3af/at MODE B pinout
Pair 3 / PINs 4, 5 are POSITIVE
Pair 2 & 4 / PINs 3, 6, 7, 8 are NEGATIVE
48V POE Option @.75A - constant draw can surge/spike to 1A:
802.3af/at MODE B pinout
You would use this option to power most 802.3af/at devices like IP Phones and Cameras
Pair 3 / PINs 4, 5 are POSITIVE
Pair 2 & 4 / PINs 3, 6, 7, 8 are NEGATIVE
24VH POE Option @1.5A - constant draw can surge/spike to 2A:
802.3af/at MODE A & MODE B pinout combined
Pair 1 & 3 / PINs 1, 2, 4, 5 are POSITIVE
Pair 2 & 4 / PINs 3, 6, 7, 8 are NEGATIVE
48VH POE Option @1.5A - constant draw can surge/spike to 2A:
802.3af/at MODE A & MODE B pinout combined
Pair 1 & 3 / PINs 1, 2, 4, 5 are POSITIVE
Pair 2 & 4 / PINs 3, 6, 7, 8 are NEGATIVE
So now that you know what the PIN OUT is (which is in our Spec Sheet on page 17 and in the product description on our web store) all you need to do is look at the spec sheet from your device and see which POE option you can use.
If they do not specify the PIN OUT polarity break out a multi-meter and cut one end off of a patch cable and strip the wires and figure it out on your own.
Also if they have a bridge rectifier circuit like MIMOSA the device will swap the polarity the way it wants it.
WARNING - If your equipment is not specifically designed to accept power on all 4 Pairs do NOT use a VH POE option.
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