Hi,
as Graham has pointed out those two external motion controllers are readily available and competitively priced, but they
have one 'ports' worth of IO (12 outputs, 5 inputs).
An Ethernet Smoothstpper has three ports worth of IO for a total of 51 inputs and outputs, a Pokeys 57CNC has 57 IOs
and a UC300 has 85 IOs. They all cost a little more but mean that if you wish to expend, particularly inputs, at a later date you can.
Craig