Which MAX model are you referring to? I thought you are referring to a HD4 but consider your use case scenario, I might be wrong.
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Any MAX with PoE capabilities
You may refer to our MAX HD series product page for more details, MAX HD2 mini and HD4 come with PoE output support (with optional PoE Activiation Kit), various on the PoE port quantity.
Thanks and regards,
Wei-Ming
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Hi WeiMing, I understand that PoE Activation Kit (Includes 1x 48V Power Supply) is required to activate 802.3af PoE Output of MAX HD2 mini. I have a clarification raised from my customer we are doing a POC with at the moment - - - if 48VDC with at least 2A is feed to HD2 mini via terminal block, will the Two 802.3af PoE Outputs enable?
Also if HD2 mini is being powered via 48V Passive POE inject at its WAN/LAN3 port as shown on the shapshot, will the Two 802.3af PoE Outputs enable?
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Hello @WeiMing,
In addition to @rocknolds question, we would like to know if a MAX is PoE from a switch, lets say for example one of the Peplink SD Switch models, will the LAN ports activate with matching PoE?
Happy to Help,
Marcus 
@mldowling, @rocknolds, you may refer to the pictures below of the outcome of the mentioned scenario. Hope it helps.
Scenario - A: 52V (or 48V) Terminal Block Power Input:
-
LAN Port #1 - PoE Output => YES
-
LAN Port #2 - PoE Output => YES
-
WAN/LAN Port #3 - PoE Output => YES
Scenario - B: 802.3at Power Input from SD-Switch (White Cable):
- HD2 Mini => No Power (it needs Passive PoE)
- LAN Port #1 & #2 - PoE Output => NO
[Update on 07 November 2019, as highlighted in this post]
The recommended power input range that enables the PoE Out is 48-56VDC.
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Hello @WeiMing,
These are great examples.
With Scenario B, I am curious as the the source as neither the Power or Status are ON (green LEDs are off), does the HD2 mini power up if you use the white cable (this is me just checking Power is ON for the source port of the white cable as I am remote and can not test this myself currently).
Appreciate your assistance,
Marcus
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@mldowling, the source (white cable) is from SD-Switch and it is able to power up an HD2-IP67 using 802.3at PoE output.
The HD2 Mini - WAN port only accept a 48V Passive PoE as power source.
I have updated the article to clarify the Scenario B power input method.
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Thanks WeiMing. How about the other scenario I mentioned above - when HD2 mini is being powered by a 48VDC Passive POE injector at its WAN/LAN3 port as shown on orignal shapshot above, will 802.3af PoE Outputs activate on LAN1 and LAN2 ports?
Furthermore with your scenario A#3 above (WAN/LAN Port #3 - PoE Output => YES):
Is this true regardless of whether WAN/LAN3 port is set to LAN or WAN?
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Scenario 4: MAX is powered via its PoE IN (WAN/LAN3) port by 48VDC passive POE.
MAX HD2 mini will definitely power on however will the POE out of LAN1-2 also activate?
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HD2 Mini can provide POE output if there is 48V power input. You may test it if you need further confirmation.
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I have a customer who will be putting the recently MAX HD4 recently acquired from us into a helicopter.
They wanted to use to use the LAN POE Out of HD4 so that it can conveniently power IP cameras. However up in there, they only have DC power source which is 28VDC.
They should be able to power the HD4 direct from this source without issue.
However, in order to activate the LAN1-4 POE out, can you please confirm that we need to feed the terminal block 48VDC? and if LAN5-8 POE out is required, another 48VDC power source is required to be connected directly again to same terminal block as shown in the photo below where I encircled by red?
Many thanks.
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Do allow me to divide your questions into the following:
-
Should i need 48Vdc to enable the POE output for HD4.
Yes, this is the standard power input requirement for all PoE output device. PoE output only will enabled if 48Vdc is connected for the device. -
How to power HD4 with DC terminal block.
- You only need 1 DC power source for the HD4 device.
Power = voltage x current
Power = 48 Voltage x X amount Ampere.
If you need need more power then you need sufficient current.
- For your case : 28VDC in Helicopter.
- May i know what is the current (Ampere) provided for the helicopter ? We have option to convert the 28VDC to higher voltage but rule of thumb is that you need to have sufficient current inorder to do so.
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Sounds like a job for the SD-PMU!
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Thanks for the comprehensive information @sitloongs!
Just a clarification for #2, I do only need 1x of power source to feed the HD4 device in order to enable POE out for all 8x LAN ports, as long as the power feed is 48VDC and has enough current capability.
For #3, the current rating of the power source is 20Amps.
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Yes, we already mentioned this option to our customer.
But, they wanted to avoid an extra hardware.
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Yes. For DC terminal block, you only need 1. You should not connect 2 DC power source via DC terminal block. Make sure you have sufficient “current” then you can power up 8 POE devices via LAN port.
20Amps 
that should be sufficient enough to power up all the devices.
Let’s us do a simple calculation by compare the different methods to power the device:
AC adapter (DC Jack):
-
Single HD4 HW1-2 AC adapter power : 48v x 2.5A = 120W, Two AC adapter = 2 x 120W = 240W
(First DC Jacks required to power 1-4 PoE LAN, second DC Jack to power 5-8 PoE LAN - Hardware design) -
Single HD4 HW3-4 AC adapter power : 56v x 2.15A = 120W . Two AC adapter = 2 x 120W = 240W
(Single DC Jack will enable PoE for 8 Ports, you need more connect 2 DC jacks in-order to have sufficient power to power up 8 PoE LAN)
DC terminal block:
- Helicopter Power source = 28v x 20A = 560W
With SDPMU, you can convert the 28v to 52v and sufficent current to do so.
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You should explain to customer that they have no choice if the need PoE output. 48v power input is the standard requirement to enable PoE.
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Do they want to avoid extra hardware due to cost or because of weight?
I can understand they would want to avoid the extra weight but the SD-PMU would be the most effective and “off the shelf” solution.
Getting a specific 28V DC to 48V DC converter would be a tricky task in its self!
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