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aerosmith9110
newbie
Topic Author
Posts: 37
Joined: Fri Oct 05, 2018 3:39 am

omnitik 5 POE daisy chaining.

Mon Jul 15, 2019 4:00 am

Hi all,

I am daisy chaining mikrotik devices basically from mt crs328-24p to another poe ap to another poe ap ( at this level poe shows short circuit even if there isn't any and won't power the device.) crs328-24p to power box to omnitik poe to another omnitik poe... Or powerbox to omnitik to omnitik.. I tried different cables from 2 meters to 15 meters ( so not cable or cable voltage / current loss )..... Did anyone able to daisy chain 2 omnitik 5 poe device?

i was able to do switch to powerbox pro to powerbox pro to omnitik 5 poe... but not switch to omnitik 5 poe to omnitik 5 poe ...that is why i am scratching my head..but if you look at the specs ( max out and max out total ) they should be able to do that... taking into account i already adjusted the voltage of the port to which the power box has the same voltage as the omnitik 5 poe...so current / voltage should not yet be a problem...

Short summary:
switch to omnitik 5 poe to omnitik 5 poe = not working
switch to powerbox to omnitik 5 = working
switch to powerbox (loaded with 3x omnitik 5 poe ) to powerbox to omnitik 5 poe (loaded with 3/4x omnitik 5 poe ) = working <----------- this is my stress test if I add one more it will not work ( reboot loop )
So if you daisy chain 2 x omnitik 5 poe the wouldn't work. but you can daisy chain 2 powerbox.

if you look at the specs ( max out and max out total ) they should be able to do that...


any help would be appreciated.
 
aerosmith9110
newbie
Topic Author
Posts: 37
Joined: Fri Oct 05, 2018 3:39 am

Re: omnitik 5 POE daisy chaining.

Tue Aug 27, 2019 8:30 am

For those who are curious this is the response to me:

Since you are using CRS328 as a power source to power daisy-chained Omnitik 5 PoE. CRS328
limits voltage when detecting hight inrush current which occurs when you connect second
Omnitik 5 PoE. When you are using Powerbox (it has dump PoE injector) your network scheme
works. Possible solutions:

1) Use PoE-Injector;
2) Change Omnitik 5 PoE to OmniTIK 5 PoE ac;
3) Change your network topology (do not use daisy chain).

So, I replied:

you could test it in your lab.. basically you could connect 2 omnitik 5 poe in series using 1 crs 328 port and one of them would not run. then put 1 powerbox pro on 1 crs port and connect 4 omnitik 5 poe on all the ports of the powerbox and it will power all 5 devices attached to 1 crs328 port. This will prove that it is not voltage / current limitation.

They replied back with :

Unfortunately, such setups can lead to short, high inrush current peaks, as my colleague stated, you should try to avoid chain setups on PoE devices which does have more than one PoE-out port.


So Draw your own conclusions but for me I think I need more convincing to believe that it is caused by " short, high inrush current peaks "
due to the fact:

1 crs328 port power 2 ominitik 5 poe in series , the last omnitik 5 poe won't even turn on.
- This only needs to power 2 omnitik 5 poe.



and yet:

1 crs 328 port and put 1 powerbox pro with 4 omnitik 5 poe on all the ports of the powerbox and it will power all 5 devices.
- This powers 1 powerbox pro and 4 pcs omnitik 5 poe basically, 1 port powers 5 devices and during my testing I was able to power a max of about 8 - 9 devices in just 1 port.

So, I am still scratching my head on " short, high inrush current peaks " but I am not electronic engineer just trying to use logic on why 1 port cannot power 2 omnitik 5 in a series and yet can power 6 - 7 omnitik 5 attached to 2 powerboxes.

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