Just to reiterate and clarify for those finding this looking for answers for wiring driver and looking at drivers. You should not hear a chirping or singing when your motors are moving. I've seen all too many youtube videos where you hear this in the background as a machine is moving. A good driver and controller will not produce this. You will hear some whirring or slight whining, but not chirping. As I stated earlier, Leadshine drivers had worked fine on another controller, but for some reason, not Pokeys, having tried three wiring configurations. Leadshine DM856 driver and motors are 4amp, so no issue there.
Most drivers can be wired in multiple ways and work correctly. This is to match different controller configurations. Unfortunately Pokeys does not come with clear instructions on how to wire correctly to a driver what type of connection to make, while drivers usually show multiple instances or examples. Pokeys does refer to it's i/o's as open collector and galvanic isolated. Not clear if that includes the motor connections or just the i//o shown in documentation. Here is a little guide explaining the sinking / sourcing concept -http://library.automationdirect.com/sinking-sourcing-concepts/
In a nutshell, if you have wires that are shared(tied to each other) and of positive polarity, this is sourcing input. If you have shared wires that are of negative polarity this is sinking.