I recently bout 2 hEX PoE RB960PGS routers. Neither of them will power my Zyxel access point. I've tried to follow instuctions for enabling POE. The only option I could find under interfaces/ethernet are for setting the individual ports to auto/force on/off. I dont see any global power on. What am I missing? Did I get two bad routers? It seems that POE should work right out of the box, right?

Are you using a 48V power supply?

I'm using the power suply that came with it, which is 24v.

Read the product page: https://mikrotik.com/product/RB960PGS

Ethernet ports 2-5 can power other PoE capable devices with the same voltage as applied to the unit. [...] It can power at/af mode B (4,5+)(7,8-) compatible devices, if 48-57 input voltage is used.

Unless your APs can be powered via 24V passive PoE, you will probably have to switch to a 48V power supply.

I saw the instructions, but am new to the POE standards. The wifi access point I have connected normally runs on a 12v power supply which is why I expected it to work.

Are you saying the Mikrotik supplied ps isn't poweful enough to run it despite being 24v? That's the only thing currently connected to the board.

If I get a 48v ps would I be able to run 3 12v APs?

You might want to check the PoE specifications of your APs instead of making assumptions.

I think what you've been trying to say, is that Mikrotik should have inluded a 48v power supply in order to make it a viable POE router.

Besides the accesspoint power supply (which is 12V) there is also an option to power through POE. The latter (possibly) has to be 48V, while the default power supply of the hEX PoE is providing 24V. In that case there is a mismatch and you have to change the power supply of the hEX PoE with the 48V version:

https://mikrotik.com/product/48POW or https://mikrotik.com/product/48v2a96w

I think what you've been trying to say, is that Mikrotik should have inluded a 48v power supply in order to make it a viable POE router.

In the end it always depends on the requirements...

As I indicated above, the Mikrotik hex poe came with a 24v power supply. The Wifi access point is 12v powered so I think it seems reasonable to think that it would work.

No, the reasonable thing to do would be checking the actual PoE specifications of your AP. If you keep guessing this discussion is useless.

If I get a 48v ps would I be able to run 3 12v APs?

I think you need to learn some basic electricity ...
Voltage has nothing to do with how many APs can be driven using POE.
You need to look at Power.

If you Hex POE has a budget of 450mA @ 48V, it can deliver 21.6W total power.
If you have APs drawing 25W each @ 48V, it will not even work for 1.

Funny how no other POE switch has required a certification in electrical engineering. Thanks for all the "help" I'll look to other brands.

@hish747

If it helps, the comparison that I usually make to explain voltage and current (and power) is with water pipes.

Imagine that voltage is pressure of the water and current is size/diameter of the pipe, while power is flow.

If you have a very small pipe with a very high pressure in it, or a large pipe with a lower pressure, you may have the same flow.

The fundamental equation is V x A = W i.e. voltage, expressed in Volts, multiplied by current, expressed in Amperes, equals the power, expressed in Watts.

Not unlike water, electricity can be delivered at relatively high voltage (pressure) in small wires (pipes) or at relatively low voltage in large wires.

There is a lot of confusion with PoE, which is a complex standard that many manufacturers (including Mikrotik) have often implemented in different ways, creating BTW the "non-standard" Passive PoE that can be anything and the contrary of it.

The PoE and PoE plus standards, respectively 802.3af and 802.3at:

https://en.wikipedia.org/wiki/Power_ove ... ementation

use anyway voltages between 42 and 57 V, because the wires the electircity is transmitted on (your normal Cat 5 or greater network cables) are tiny so a relatively high voltage is needed to deliver the needed power.

The 802.3af is limited to lower power devices.

What you need/will be using is the 802.3at.

It is limited by the standard at a power at the PD (Powered Device) of 25.5 W.
Mikrotik put a limit to the amount of current each port can deliver at 450 mA (or 0.45 A) on a single port when using the (higher) voltage the PoE 802.3at demands.

So, to draw the maximum power allowed you need 25.5 W / 0.45 A= 56,67 V.

If we take (as an example) a Zixel AX 3000:
https://www.zyxel.com/global/en/product ... ifications
it needs 20.5 W.
20.5 W / 0.45 A = 45,55 V

Since a few Volts will likely be "lost" in the length of cable between the PoE router/switch and the AP 48 Volts is the minimum you can expect the AP to work with.

The "size" of the PSE (Power Sourcing Equipment) depends on how many devices you are going to power.

The hEX PoE can consume up to 54 W per specifications, so if you have only one AP connected to it your power supply should be capable of powering 54+20.5=74.5 W (very likely the hex Poe will need much less than that in normal operation, still ... )

If the voltage is 48 V, you need 74.5 W / 48 V = 1.55 A, in practice you need a 48 V / 2A power supply, or more likely you will find 80 W PoE injectors that are 54 or 56 V (54 V x 1.5 A = 81W, 56 V x 1.45 A = 81,2 W), example:
https://en.cdr.pl/p5249,ubiquiti-gigabi ... v-80w.html

The power supply that you got togeher with your hex Poe is a 24V 2.5A one and - besides the fact that voltage is not 802.3at compatible - it can only power the hex as 24 V x 2.5 A = 60 W, very similar to the max power of 54 W in specifications.

Thank you for that throrough explanation, jaclaz. You hit it right on the head with the Mikrotik passive poe issue. Other condescending replies (NOT yours) notwithstanding, I do have a basic understing of voltage, amperage and wattage, as well as plumbing by the way. Not to flex, but I built a whole second level to my house and did the plumbing electrical and hvac.

What I don't understand is Mikrotik's decision to include an inadequate power supply. This nonsense can be avoided by just shipping an appropriately rated power supply that covers enough bases to make this this a viable poe router.

Also...Mikrotik, please ship a microscope along with your products to be able to read the included instruction manual. Just saying.

No, It would be impossible, the load can vary between the base 54 W and 54 + 4 x 25,5=156W.
A lot of people buy the hex PoE only because of the SFP and gigabyte interfaces and don't power any other devices or maybe a single 802.3af one.
They won't like the increased cost (for *some reasons* the cost of higher power ones is proportionally bigger) and - besides It would be less efficient from an energy viewpoint.
What they could do would be to offer as option different PoE power supplies capable to drive the hex and 1, 2, 3 or 4 802.3at devices.

hEX PoE is not at PSE, it's only af ... it can only provide 450mA per port while at requirement is 600mA.

@mkx
I think you are misreading the standard , it requires support for 25.5 W and states a maximum current of 600 mA.
450 mA at 57 V make 25.65 W, so, if the hex PoE can actually deliver that in practice, it is 802.3at compliant.

My reference is wikipedia article on 802.3 PoE. And it says that 802.3 at PSE (the device providing power) should provide up to 30.0W at 50.0V - 57.0V.

The one figure, which is almost but not entirely correct in your post (25.5W, you're mentioning 25.65W), is power which is supposed to be available to PD (powered device), but standard requires 600mA and makes provisions for losses in cables. hEX PoE might almost fit the bill as 802.3 at PSE if the connection between hEX PoE and PD is really short.

But anyway, 450mA current limit says hEX PoE isn't 802.3 at device, no matter what power budget claculations for some marginal use case are. hEX PoE is a very decent 802.3 af device in best case.

Yep, my reference is the same, I am reading it a bit differently.

But the standard is (IMHO) a mess.

First thing the "allowed" voltage is 50.0–57.0 V at the PSE and 42.5–57.0 V at the PD which makes no sense, either it is "included" or "allowed" in the standard a voltage drop up to 7.5 V (the 50 at the PSE that can be as low as 42.5 at the PD) or no voltage drop is included (the 57 V at the PD are exactly the same 57 V at the PSE).

So if you power a 802.3at PoE device with a (common enough) 48 V power supply you already are out of the standard as the minimum voltage at the PSE is 50 V.

On the other hand with 48 V at the PSE you can easily have more than 42.5 V at the PDU (so you are within the standard), with normal Cat5 cables at 100 mt (which is the max length) 48 V for a 25.5 W device become (according to calculators such as http://poe-world.com/Calculator/ ) 43.02 V so still slightly above the minimum 42.5 V (current will be 590 mA - i.e. within the max allowed 600 mA and power at the PSE will be 28.45 W - i.e. within the max allowed power of 30 W).

Now if you go for the maximum voltage allowed (57 Volts) and limit the current to 450 mA (as Mikrotik seemingly does) the Mikrotik should be able to provide at the port 57V x 0.45 mA = 25.65 W - i.e. slightly more than what the standard requires.

Surely you need a very short cable between the Mikrotik port and the device at the limit of the 25.50 W (which makes the whole "remote" PoE mostly useless).

Since no manufacturer (in their right mind) would make devices actually needing 25.5W (at least from specs most 802.3at declared devices are within 22 W) in many cases you can probably get away with the limited current the Mikrotik provides.

But surely Mikrotik is walking a fine line.

The 802.3af max current is 350 mA, if we compare the max current we see that the max current at the minimum voltage gives the max power at the PSE:
802.3af 44 V x 0.350 A = 15,40 W
802.3at 50 V x 0.600 A = 30,00 W

then the power at PD is seemingly 84-85% of the power at the PSE (15.40 x 0.85 = 12.94 and 30.00 x 0.85 = 25,50), and here things get again murky, so if some 15 % power loss is included in the specs (between the PSE and the PD) for the minimum allowed voltage, if we maintain a fixed max current, we can have 350 mA at 57 V which makes 19.95 W at the 802.af PD and 600 mA at 57 V which makes 34.20 W at the 802.at PD, whcih exceeds the specs.

Well ... there are two distinct sets of numbers, one for PD (e.g. 42.5V-57V, 25.5W) and one for PSE (e.g. 50.0V-57.0V, 30W). And these two loosely correlate (over up to 100m of CAT5 UTP cable). The only common value is rated max current which is 600mA for at devices. hEX PoE as PSE should comply with PSE numbers ... and it doesn't.

All the rest is wishful thinking.

I can see you're a bit confused about PD vs PSE specs. So a short example: let's say PSE outputs power at 57.0V. And PD is connected with a very short cable and drawing a tiny amount of power. This means voltage drop on cable is almost 0V, hence PD has to accept 57.0V on input. Another example: PSE outputs power at 50.0V, PD is connected with 100m of marginal UTP cable and is drawing high power ... which means voltage drop of around 7.5V ... substract that from supply voltage and you get 42.5V on input of PD and that device has to live with it.

Both use cases are realistic and PD has to live with both. I'm pretty sure that the whole voltage range, allowed for PSE, is not meant for creative power budget calculations, instead it's meant for non-ideal power adapters (in old times not every PA was switching power supply and voltage regulation was a bit harder task). Some power adapters could drop voltage considerably when under rated load. And newer PoE standards (bt) are making permitted output voltage from PSE narrower (moving lower value towards 57V while keeping upper value at 57V).

All this jibber-jabber is very interesting, however, every other POE device I've ever bought and used just works with whatever I plug into it. I guess I've stumbled onto a hobby rather than a consumer device. All good.

It seems You are confused by passive PoE and active PoE. I will oversimplify this, but the main visible difference is in voltage. Hex poe can deliver both but not in same time. With included 24V PSU it delivers passive PoE. For active PoE (I assume your devices needs active PoE) you need 48V PSU. Why there is 24V PSU included instead of 48V PSU? I believe it is because hex means h-ome ex and Mikrotik home devices are passive PoE powered. There are Mikrotik PoE switches which can deliver passive and active PoE simultaneously, but they are more expensive.