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.
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!
