I am only guessing here, you need to find out if the drives will take a step and direction.
I have a different controller that came with a machine we scrapped for parts. The four drives in it were meant to be run from a program which used the RS232 to flash the memory on the drives. It was a high end robotics machine.
After talking to the manufacturer, he said yes they will take step and direction, but the drives are just not meant
to run in that manner, and even if you get them to work i would not be satisfied. May be applicable to yours also
so maybe talk to a tech rep of the company.
FWIW,
RICH