Hi mates, I have a Dahua doorbell system, 2 doorbells need PoE 802.3af (few watts), 1 monitor which needs 12Volt (I’ll just wire 1-2-3-6 ethernt pins) and one wireless cAP lite AP which needs PoE too.
I think the good solution is to buy RB750UPr2 but I’m not really sure about it, I have some questions about:
The PoE ports are managed/protected by electronics? I mean, if somebody will cut me a wire outside, or a device may create by time short circuit/extra current, this device will stop to power that port leaving the other active? I have some dubts there is a simple internal wire connecting power pins (4-5-7-8), cause it’s never declared as 802.3af and say to works till 30 volt (??). If this router is not proper, may you please indicate me one? Thank you
the RB750UPr2 is sold without power supply? Should I buy one 48Volt?
https://mikrotik.com/product/RB960PGS
The RB960PGS (HEX POE) is rated to 57v and includes a 24v power supply. It is passive power, so it will supply what ever you input to it. All Mikrotik POE ports are (4,5+)(7, to my knowledge.
All Mikrotik devices send out on PoE outputs the same voltage they get on their input. So with a 48 V power supply on a hEX PoE all outputs will give out 48 V the doorbells require (the cAP lite doesn’t care much as it accepts from 10 to 60 V), but you have to obtain the 48 V power supply separately, the bundled one gives 24 V and there is no upconverter in the router itself.
Regarding the overload/short circuit, as the device can measure the load on individual ports, I’d suppose it disconnects a port if it takes too much power, but whether the detection it is fast enough to withstand a short-circuit is out of my knowledge.
Thank you a lot for your precious help!
Very good infos, let me go deeper with that, the PoE system is well projected and consider all possible situations to avoid any damage, the device will test in every port some conditions between wires before give out the power, which occurrs after some time, can be seconds too. There is an active power management usually defined in 802.3af which I don’t read in the router specifications ( but maybe in the second one there are, I’ve to 3ead about) I would know if Mikrotik has this manage, thank you
Thank you a lot! Now it’s clear, to reduce costs it’s more convenient for me to buy a RB941-2nD hAP lite which should be enough for home usage and a Dahua PoE switch (the same brand of doorbells) to manage power correctly in any conditions that may happen in future.
As RB941-2nD hAP lite is very small I can fix it like a WiFi AP on the wall, putting switch and the most of ethernet wires inside the electric box
to my knowledge.