Community discussions

MikroTik App
 
dadaniel
Member Candidate
Member Candidate
Topic Author
Posts: 205
Joined: Fri May 14, 2010 11:51 pm

RB5009UP wrong description/datasheet?

Wed Jul 13, 2022 2:58 pm

The description and datasheet of RB5009UP seems to be wrong: PoE-out 802.3af/at require at least 48V. It is not possible to power non-mikrotik 802.3af/at devices with lower voltage. I doubt the routerboard has a built-in step-up converter for PoE-Out.
 
User avatar
rextended
Forum Guru
Forum Guru
Posts: 9479
Joined: Tue Feb 25, 2014 12:49 pm
Location: 🇮🇹, my 💔 is in 🇺🇦

Re: RB5009UP wrong description/datasheet?

Wed Jul 13, 2022 3:09 pm

On out you have the highest voltage that power the device.
Is written everywhere.
If you need to power 802.3af/at device, somply provide a voltage between 50 to 57V
If you need to power only MT devices, you can provide only 24V
If you need mixed cases, use the already existant CRS-8P
 
dadaniel
Member Candidate
Member Candidate
Topic Author
Posts: 205
Joined: Fri May 14, 2010 11:51 pm

Re: RB5009UP wrong description/datasheet?

Wed Jul 13, 2022 3:22 pm

Ok, but then they should mention that passive PoE is supported in datasheet. They only wrote 802.3af/at everywhere.
 
Zacharias
Forum Guru
Forum Guru
Posts: 3468
Joined: Tue Dec 12, 2017 12:58 am
Location: Greece

Re: RB5009UP wrong description/datasheet?

Wed Jul 13, 2022 3:35 pm

Ok, but then they should mention that passive PoE is supported in datasheet. They only wrote 802.3af/at everywhere.
All power options support a wide voltage range of 24 – 57 V
https://mikrotik.com/product/rb5009upr_s_in
 
mkx
Forum Guru
Forum Guru
Posts: 8936
Joined: Thu Mar 03, 2016 10:23 pm

Re: RB5009UP wrong description/datasheet?

Wed Jul 13, 2022 7:09 pm

Ok, but then they should mention that passive PoE is supported in datasheet. They only wrote 802.3af/at everywhere.

Agree that MT should spend a few more words on powering. Mainly because of flexibility which often confuses unsuspecting users.

Such as explicitly mentioning that 48V (or more, up to 57V as per standard) power adapter is required for standard 802.3 af/at PoE operation (quite a few users assumed that device has built-in voltage up converter). (BTW, IMO MT should start selling a 54-56V power brick instead of 48V one to allow for slightly larger voltage drops on UTP cables). And explicitly mentioning that PoE out voltage is the same as highest source voltage (if device is powered by multiple power sources) and that it should be powerful enough to support all power "sinks" (including device itself and all PoE powered devices) because "load sharing" between different power sources doesn't exist (except in some extremely rare conditions). This is specially painful when one of power sources is PoE which is often with highest voltage and lowest power capacity.
 
User avatar
rextended
Forum Guru
Forum Guru
Posts: 9479
Joined: Tue Feb 25, 2014 12:49 pm
Location: 🇮🇹, my 💔 is in 🇺🇦

Re: RB5009UP wrong description/datasheet?

Wed Jul 13, 2022 7:17 pm

One little note, that do not invalidate anything, but IEEE on 802.3af/at define Wattage limit, and do not "talk" directly about the Voltage.
The "48" is jus a standard de-facto, but can be 30W at 24V and still 802.3at...
 
User avatar
chechito
Forum Guru
Forum Guru
Posts: 2546
Joined: Sun Aug 24, 2014 3:14 am
Location: Bogota Colombia
Contact:

Re: RB5009UP wrong description/datasheet?

Wed Jul 13, 2022 9:28 pm

maybe is a good idea for such a versatile device to create a compatibility matrix of PoE output, something like:

NON OFFICIAL JUST AN EXAMPLE
poe-matrix.png
NON OFFICIAL JUST AN EXAMPLE
You do not have the required permissions to view the files attached to this post.
Last edited by chechito on Wed Jul 13, 2022 9:30 pm, edited 1 time in total.
 
Zacharias
Forum Guru
Forum Guru
Posts: 3468
Joined: Tue Dec 12, 2017 12:58 am
Location: Greece

Re: RB5009UP wrong description/datasheet?

Wed Jul 13, 2022 9:28 pm

The "48" is jus a standard de-facto, but can be 30W at 24V and still 802.3at...
Any reference on that ?
 
User avatar
chechito
Forum Guru
Forum Guru
Posts: 2546
Joined: Sun Aug 24, 2014 3:14 am
Location: Bogota Colombia
Contact:

Re: RB5009UP wrong description/datasheet?

Wed Jul 13, 2022 9:31 pm

The "48" is jus a standard de-facto, but can be 30W at 24V and still 802.3at...
Any reference on that ?
I think any 802.3 PoE is 48v at 24v will be passive PoE
 
User avatar
rextended
Forum Guru
Forum Guru
Posts: 9479
Joined: Tue Feb 25, 2014 12:49 pm
Location: 🇮🇹, my 💔 is in 🇺🇦

Re: RB5009UP wrong description/datasheet?

Wed Jul 13, 2022 9:43 pm

What is the definition of "passive"?
Do not chech if the device is poe-capable and supply the power regardlessly?
(like passive poe injector provided for some device)

Or generically 802.3 is like what is present on CRS-8P that provide the right 24V or 48V on device, checking the impedance/resistance (I do not know it on detail) of the circuit before apply power?
The CRS-8P can distinguish successfully mikrotik devices that support 48V or 24V, also camboom (not medulla) and ubiquilly products, hikkupvision cameras (not all models), etc. without forcing poe...
 
Zacharias
Forum Guru
Forum Guru
Posts: 3468
Joined: Tue Dec 12, 2017 12:58 am
Location: Greece

Re: RB5009UP wrong description/datasheet?

Wed Jul 13, 2022 10:01 pm

In passive POE there is no handshake procedure... so no POE classification...
But i' ve not seen any af device running on 24V... That is why i asked if there is any reference on that ....
 
User avatar
rextended
Forum Guru
Forum Guru
Posts: 9479
Joined: Tue Feb 25, 2014 12:49 pm
Location: 🇮🇹, my 💔 is in 🇺🇦

Re: RB5009UP wrong description/datasheet?

Wed Jul 13, 2022 10:17 pm

I do not have any precise reference, I do not notice Voltage written when I see 802.11af/at, only Wattage ¯\_(ツ)_/¯
 
User avatar
rextended
Forum Guru
Forum Guru
Posts: 9479
Joined: Tue Feb 25, 2014 12:49 pm
Location: 🇮🇹, my 💔 is in 🇺🇦

Re: RB5009UP wrong description/datasheet?

Wed Jul 13, 2022 10:21 pm

But on CRS-8P that have both 48 and 24, , if I plug non mikrotik device like a PMP450i are provided 48V, if I plug AF5XHD or AF60-LR, are provided 24V without force anything.
The handshake do the choice....???
 
Zacharias
Forum Guru
Forum Guru
Posts: 3468
Joined: Tue Dec 12, 2017 12:58 am
Location: Greece

Re: RB5009UP wrong description/datasheet?

Wed Jul 13, 2022 11:43 pm

To my knowledge there is no handshake on Passive POE.
Only a resistance check ( detection process ), and if the PSE detects that there is a PD connected that meets the resistance requirements it will supply with Voltage the Device connected...

However, on POE af,at,bt etc, after the detection process, there is the classification process, the PSE will send a classification signal to the PD device which will then answer with its Class type and the PSE will finally supply the correct voltage according to the POE Type and class negotiated...
 
User avatar
jbl42
Member Candidate
Member Candidate
Posts: 157
Joined: Sun Jun 21, 2020 12:58 pm

Re: RB5009UP wrong description/datasheet?

Wed Jul 13, 2022 11:51 pm

But on CRS-8P that have both 48 and 24, , if I plug non mikrotik device like a PMP450i are provided 48V, if I plug AF5XHD or AF60-LR, are provided 24V without force anything.
The handshake do the choice....???
The PMP450i supports 802.at active PoE in.
The CRS-8P supports 802.3af/at @48V and passive PoE @24V out.

If 802.3af/at handshake succeeds, CRS-8P provides 48V. If not, it falls back to passive PoE providing 24V.
 
User avatar
rextended
Forum Guru
Forum Guru
Posts: 9479
Joined: Tue Feb 25, 2014 12:49 pm
Location: 🇮🇹, my 💔 is in 🇺🇦

Re: RB5009UP wrong description/datasheet?

Thu Jul 14, 2022 12:39 am

If "fallback" on failed handshake must poer also my gigabit laptop, but do not do that.

And another:
If 48V (+24V) is also present, supply the 48V to wap ac,
If 48V is not present, provide 24V to the wap.
But I never see the CRS-8P that power 8 wire device with "passive poe" if a non-poe gigabit device is simply attached.
 
mkx
Forum Guru
Forum Guru
Posts: 8936
Joined: Thu Mar 03, 2016 10:23 pm

Re: RB5009UP wrong description/datasheet?

Thu Jul 14, 2022 7:10 am

I do not have any precise reference, I do not notice Voltage written when I see 802.11af/at, only Wattage ¯\_(ツ)_/¯

FWIW, wikipedia article on PoE has a detailed table under "Standard implementation". I've no reason not to trust those figures ... and it includes voltage ranges both at PSE as well as PD.
 
mkx
Forum Guru
Forum Guru
Posts: 8936
Joined: Thu Mar 03, 2016 10:23 pm

Re: RB5009UP wrong description/datasheet?

Thu Jul 14, 2022 7:19 am

In passive POE there is no handshake procedure... so no POE classification...

Mikrotik PoE documentation says:
Passive PoE-Out up to 30 V - PoE standard, which does not require negotiation between PSE (Power Sourcing Equipment) and PD (Powered Device). For PoE-out uses the same voltage as supplied to the PSE (Power Sourcing Equipment). PoE-Out Standard for devices which supports input voltage up to 30 V. PD resistance on spare pairs should have range from 3kΩ to 26.5kΩ.
(text for passive PoE-out up to 57V is essentially the same). The highlited part indicates that passive PoE-out doesn't blindly enable power, instead PD still has to offer certain (static!) characteristic. With 802.3 af/at/bt/... that characteristic is dynamic (i.e. resistance changes with time) to negotiate power class of PD and is as well explained in the link I posted in previous post.

Since even passive PoE PD needs to show certain characteristic and gigabit kaptop doesn't, that laptop still needs its own power adapter to fry itself.
 
User avatar
macgaiver
Forum Guru
Forum Guru
Posts: 1753
Joined: Wed May 18, 2005 5:57 pm
Location: Sol III, Sol system, Sector 001, Alpha Quadrant

Re: RB5009UP wrong description/datasheet?

Thu Jul 14, 2022 10:49 am

maybe is a good idea for such a versatile device to create a compatibility matrix of PoE output, something like:

NON OFFICIAL JUST AN EXAMPLE

poe-matrix.png

NON OFFICIAL JUST AN EXAMPLE
Power from PoE-in CAN'T be used for PoE-out, it is used only to power board itself (if that is highest incomming voltage)

Who is online

Users browsing this forum: No registered users and 8 guests