The radio/poe power is completely isolated from the control power (which
comes from the base unit) on the 4 channel gigabit poe's, and the power for
the PoE's defaults to on without a control voltage.    The base unit
currently only works on positive voltages.

One of the options we're looking at on the rackinjector is providing some
internal terminals for a small DC-DC converter which would be mounted
either on or just behind the control board.

On Sat, Apr 14, 2018 at 8:16 PM, Seth Mattinen <> wrote:

> On 4/14/18 6:09 PM, Forrest Christian (List Account) wrote:
>> For various reasons you need positive voltage if you're doing traditional
>> power-interruption canopy style sync.  I.E. the type of sync which the
>> PowerInjector+Sync will do.  This general statement might not be 100% true
>> with the 450i (and perhaps some other more recent radios), but suffice it
>> to say that negative voltages aren't easy to deal with for sync.   Because
>> of this requirement the PIPS requires positive power.
> Makes sense. I was thinking about using some to power stuff that doesn't
> need sync (licensed radios) since I had them on hand instead of buying
> something. Does the power only SiteMonitor 4 Channel Gigabit PoE Injector &
> Controller will work fine with -48VDC or does its control power come over
> the bus connectors from the base unit? But then I think I remember a thread
> where the sitemonitor base unit itself only works with positive voltages.
> On the rackinjector, we support the newer Cambium style sync, which
>> doesn't much care about polarity, and also a polarity agnostic board which
>> also doesn't care about polarity.  For this reason, you can feed negative
>> voltages into the rackinjector.  Currently, you have to have at least one
>> of the three power supplies feeding the rackinjector set up for positive
>> voltage, and the other two can be positive or negative or whatever you
>> want, depending on the requirements of the expansion cards and the radios.
> No problem for me to throw a small DC-DC converter in the mix and feed it
> a positive voltage on one of the inputs for controls.
> ~Seth

*Forrest Christian* *CEO**, PacketFlux Technologies, Inc.*
Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602 |
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