i dont if this helps but i have the dm500hd original
and it does'nt have a 9 pin com port so you cant use
a null modem cable. and this is the way to use dreamup
on the dm 500 and 800se as they both the same just a mini usb port on them,
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Manual update firmware DM 500HD via mini-usb & Lan Network
Items required:
1) mini-usb male to male [same as a camera USB] & Cat5 Network Cable
2) Universal DreamUP 1.3.3.5
Process:
1)Unplugged the Dream 500HD
2)We connect the cable for its part mini-usb port and
"Service" of the Dream 500HD and the USB to a USB port on your PC
and also the Lan Cable from your Router
3)Just plug it in, the PC will detect new hardware connected to the system:
4)The PC will ask the driver for this new component,
Windows 7 will download the driver Auto
the driver is cp210x usb to uart bridge controller if you need to find it
5)Open the Windows Device Manager,
and you will see the new hardware installed,
will appear as COM port (even a USB cable).
In the following example, is recognized as the cable into the port COM4.
6)We opened the universal DreamUP 1.3.3.5 (for example)
and select the update COM port (like any other model of Dreambox).
At this point, we choose the COM port that we appeared in the previous step
(COM4 in this example).
7)Press the Connect button the DreamUP universal and we can turn
the Dream 500HD to start loading new firmware.