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The ecg-p2s can control 2 strings each with up to 4 universes so no problem to drive your 640 channels. What you will have to do though is break your pixels up into groups. Suggest 4 groups of 45 pixels could be OK and supply your 5V power (assuming you have 5V pixels) separately to each group as the curent rating of the wire in between the pixels is not big enough to drive 180 pixels.
You could connect your pixels all in one long string as long as the max distance from your ecg-p2s is not more than around 5m and as long as you don't have more than 5m max between pixels. Otherwise you can split the data into two groups and wire each one to you ecg-p2s.
Usually you mount your ecg-p2s close to your pixels and then run ethernet from it to your PC or other controller.
You can set up the configuration of your pixels after you decide how to mount them. You need to do this both in your ecg-p2s and you will also have to give it an IP address so your software (whatever you use) knows where to find it.