You are probably trying to achieve something that giving a straight yes or no answer to the question wouldn't really help you with.
As DMX is actually just a 512 byte block of data that is put out on the wire and retransmitted again approx 60 times a second, starting at 256 doesn't make any real sense as whilst DMX blocks can be shorter that the full 512 bytes, to send something at address 256 you have to sent the 255 bytes for address 1 to 255 first anyway.
From your question It kind of feel like you might be wanting to make something else send in those lower addresses which you cant do.
I understand how it works i have some cheap Wireless that only transmits 256 channels i need the second half of the universe......where do i change it?
starting in 2.7 it's in the setup. Setup>System>Output>DMX. there is a list of outputs, those are physical DMX ports. if there are many you can find the correct one by looking at the serial number of the gadget.
after changing this you will need to restart the Eos software
