For this purpose they have the, so called isolation card that is mounted on the side of the lenze controller heatsink. The 3wires left goes to lenze, the other to mains and 0-10V from CSMIO.
If the motor should run in rev than you must wait, until complete standstill and maybe half a second, before you can switch the direction. Eventually you can add a second photo sensor and wait until no signal changes occur. Lenze wants a zinkoxid varistor, don't ask what that is.
How do you have transformed the 5V from CSlab Controller to the 12V that the stepperdrivers want, I'll try to use the ULN2803 like in the 2 additonal stepper boards. But I don't know from the datasheet if they make a H or L output wih a H-input.