thanks for the information.... seems like a big headache to config and manage avalon 921.... how many Raspberry Pi do you need to manage 40 rigs of avalon 921
It's been a while since I had any 921 but each RPi can do 20 *in theory* in reality I never got more then a dozen on one before it started to have issues so 3 or 4 would be a more reasonable number.
I was using a RPi2 so if you use a RPi3 you might be able to get 20 on one.
You also need the cables and AUC3 don't forget those.
There are some setup video around the net / youtube that help.
-Dave