POE & RB750-PBr2

[eomedia]

So not exactly sure I'm validating this correctly but figured I'd post it for some feedback.

I have the following test setup.

RB750 switch [ http://routerboard.com/RB750P-PBr2 ] powering three AirMax radios.

- (2) RocketM900 radios (could be any AirMax radio)
- (1) NanoBeam AC 19

RB750 powered via provided AC cable and POE adapter all radios power correctly - no issues.

If however I power ths RB750 via the ws-12-dc-250 switch using 24V it's a different story. With just the (2) Rocket M900 radios connected there are no issues and the power consumption is around 10.6 - 11.1 on the port - once the NanoBeam is plugged in the ws-12-dc-250 switch will reboot. If a single 24v (.75A) port can support 18w of power that would seem to mean that when the NanoBeam is turned on the power requirement likely exceeds the limit and causes the switch to reboot even though individually the units would seem to be under that limit as they are not running at full power.

If this is confirmed behavior I have no issue as the port is operating as expected - just wanted to confirm.

Also, could we use 48v with converter [ http://routerboard.com/RBGPOE-CON-HP ] to power the device but lower the watts to the point where it wouldn't exceed the capacity of the port?


USE CASE: The reason for this use case was we have a difficult cable run that went around an entire house (under deck, over windows/doors, etc.) and at the end of that run we wanted to add an additional ptmp radio as well as a ptp link and rather than running additional cables we had hoped to utilize the RB750 switch to quickly add the new radios using the existing cable until we could run additional cable in the spring.

[sirhc]

airMAX radios can use up to 12+ watts each when transmitting

You are trying to power (3) airMAX radios which can be up to 36 watts plus power the RB

You are going to damage the switch port if you have not already.

24V is limited to .75A constant draw which is in only 18 watts

[sirhc]

If your limited to 1 cable up to the radios use a WS-6-MINI powered by a 48VH port on the WS-12-250-DC

[eomedia]

With the ws-6-MINI - you are suggesting putting it in a ENC-SW-8X5 at the end of the line and then because it's POE-in 48v it should have the necessary power to manage the three local radios. I have that correct?

This is essentially the same logic I was trying to use the RB750 for except that it can only manage 24v in which is where the issue occurs related to watts per port which sounds like it's confirmed.

Thanks

[sirhc]

Yes, the WS-6-MINI will be more than capable to power these radios.

Yes the WS-6-MINI has 100+ watts as a POE budget.

Just do NOT try to power an airMAX radio with port 2 of the WS-6-MINI as port 2 only provides 24VH and 48VH which are for airFIBER radios only, but ports 3-6 support 24V and 48V and 24V is for airMAX radios not 24VH which is power on all 4 pair.

Powering an airMAX radio with 24VH will fry the radio and the port in the switch.

As I said there is a good chance you may have damaged the port in the switch trying to power (3) airMAX radios and an RB with standard 24V as it would exceed the capacity of the Ethernet Transformer. (3) x 12 watts + 5 watts for the RB = 41 watts or 1.7A @ 24V and this does not take into account INRUSH current which is higher.

To test that port is probably OK do this:
1) Remove all cables from port and do a cable diagnostics, if you get back OPEN, OPEN, OPEN, OPEN then this is one good sign.
2) Plug your laptop into that port with POE OFF and make sure you still get a 1G connection.
3) Transfer a large file back and forth across the switch port with your laptop and if you do not get any errors then the port is "probably" OK

When using the WS-6-MINI you are feeding it 48VH @ 1.5A powered on all 4 pair which provides plenty of watts at 24V

[lligetfa]

Yes, the WS-6-MINI will be more than capable to power these radios.

Yes the WS-6-MINI has 100+ watts as a POE budget.

Do keep cable length in mind when calculating voltage drop. Yes, there is a 100W budget but voltage drop over distance could fill your log with alerts. Feeding it with 50V instead of 48V gives you 2V more margin. The AF PoE brick and the WS 48VH is actually 50V. 48V is just a nominal term used to avoid confusion.

[sirhc]

We are adding a feature to the WS-6-MINI firmware to ignore input voltage drop conditions like Les has so it will not fill the log.

But remember Les is using a 100 meter cable which is worst case as far as voltage drop and since you are powering all 24V devices the 24V the WS-6-MINI will output will be exactly 24V as it conditions the 24V output stepping it down from the 48V input.

In Les's situation the voltage drop is passed on as the WS-6-MIN 48V output voltage which is still capable of driving his 48V POE devices as most POE devices have a range of acceptable input voltages many as low as 35-37V is sufficient to power them.

We are working on a new product due out later this year to fix this voltage drop issue. Eventually the WS-6-MINI will be replaced by the WS-6-100 which will compensate for this cable drop to insure it always passes 48-50V out as it's 48V POE option correcting for any voltage drop on long cable runs.

We also have a new very small SMART DC switch in the works due out in a couple months. Its very similar in size to the WS-6-MINI but with the POE IN and barrel connector removed and replaced by a small green terminal block which will allow the unit to accept 9-80V DC in and still be able to power 24V and 48V devices. This unit has (4) POE ports,(1) SFP port, and a USB serial port. As well it will still fit in the same Tycon box as the WS-6-MINI does now. The idea is you can mount it on the tower and hook it directly to a 12/24/48 volt battery bank and it conditions the power for you compensating for any voltage drop on the cable and allowing you to execute DOD to your needs. This unit is also built to not be affected by FM tower emissions that the WS-12-250-DC unit is experiencing currently.

As well we are making changes to the WS-12-250-DC to correct the issue with FM tower emissions and those improvements will be incorporated in future productions of that model this summer.

These are just a few of the things coming out this summer!

Our first radio product will be out this summer as well as a lot of other new categories of products geared to help WISPs who are our targeted market with over tones into the industrial integrator market.

[lligetfa]

...WISPs who are our valued targeted customers.

While I might not be your target customer, the same Ohm's Law applies to WISPs and non-WISPs alike. The MINI knows not that the PoE loads are cameras and not radios.

Good to hear about all the new stuff you're working on.

[eomedia]

Following up on this thread in a related question -- powering the WS-6-MINI via POE-IN on port 1.


Enclosure with DC power located fair distance from WS-6-MINI location - want to power switch via POE-IN. Inability to add Netonix DC switch in enclosure at this time (perhaps future) and curious how you could power MINI.

Something like a TP-DCDC-2448-HP which provides 56VDC Passive POE Output?
http://tyconsystems.com/index.php/dc-pa ... dc-2448-hp

Or the Gigabit version?
http://tyconsystems.com/index.php/dc-pa ... c-2448g-hp

In testing around the shop I used a simple UBNT 48V 0.5A Carrier PoE Adapter and it powered the switch up fine but at the site PoE-IN is the only real option.

[eomedia]

anyone with an idea/suggestion?