We’ve been trying out the CRS112-8P to power remote sites with a handful of 48V & 24V POE devices, but we keep running into an issue where the 24V devices don’t want to power up. Whether the port is set to auto or forced on and low power, it keeps showing “low voltage” under interfaces. In the current setup I’m having a look at there is a Ubiquiti Nano being connected and according to the specs it’s well within the power budget and should theoretically be able to run from the CRS, but no amount of fiddling has made it so. Upgraded the firmware to the latest but still no go (7.16.1).
Yes. CRS doesn’t regulate voltage internally, it only passes whatever supplied. CRS112 is one of few MT devices with dual power input, allowing to select voltage for PoE-out. If one of inputs is missing, corresponding PoE-out voltage is missing as well.
Indeed MT PoE offering is pretty inconsistent … but there are a few rare devices which fare a tad better:
CRS328-24P-4S+ has internal dual-voltage power supply and offers per-port selectable voltage (24V passive PoE or 48V 802.3 af/at) … unfortunately it has limit if around 24W per port
CRS320-8P-8B-4S+ is a recent addition to the fleet and offers 802.3 af/at/bt (POE++) … the eight bt ports support whooping 80W while other 8 ports support modest 26W.
Oh yes, have used the CRS328 before, that’s much more like it, and that 320 looks very promising. Really would be great though to get an 8 port equivalent as well. Can’t always justify a full size switch.
MikroTik CSS610-8P-2S+IN is your friend then. I have 7x 48V real POE devices and one 24V Device (DISC Lite ac). Works fine!
Being an CSS, it only comes with SWOS lite. While SWOS is the better choice for most pure switches due to being much more userfriendly, the lack of Syslog can be annoying.
For the Switches actually needing dual Voltage supply I would be happy if MT would offer a Power source with 24V AND 48V or some sort of step-down-device from 48V to 24V you could just plug between the 48V supply. Or something like that.
Yes, that would be something in the right direction.
I had in Mind somthing with some barrel-socket or Terminal Input (24V or 48V) and then two barrel plug output: 24V and 48V, especially for this switch. I mean if mikrotik built a device for 48V POE to power the stupid 24V devices with no real normal POE, it would be a minor jump to produce something like that.
Perhaps I will modify my CRS112-8P with some 48V->24V DC-DC-konverter to stop fiddling with two power supplys. Around 13€ cost some sulution, it would be worth it for me. There are obviously no dual-voltage Power supplys, or they are with DIN-Rail mounting and not be electrical safe in my use case.
Disadvantage is the lack of emergency supply due to only 1 Power supply instead of 2, but if the 48V POE-Devices don’t work, it has no use anyways.
It is like almost all Mikrotik devices: Nice and feature rich, good to use, but not really thought through till the end in the first Revisions (speak of an 48POE-Switch with single power supply or new AX Access Points with 24V instead of normal POE with 48V, to name the most annoying in my personal context. I wouldnt complain if it wouldn’t be there in the AC-Versions and so I got used to power a DECT-Base or IP-Phone on eth5 with 48V POE…)
