grounding question

[hswaters]

I have a PMDX-416 and mach4 on my plasma torch table.  I have installed a Proma SD 50 torch height controller.  The Proma shows taking the output of the PMDX step and dir signals to the Proma and from the Proma to the stepper controller.  Basically inserting the Proma in the circuit between the smartbob and the stepper controller.  The Proma instructions show connecting the power ground to the step and dir grounds. 
The Proma needs 7 to 35 volts for power.  I cannot get that much from the smartbob so I get it from the 10 amp power supply that runs the motors.  So the smartbob and the power supply grounds are both separate.  Will I have a problem if I tie these two grounds together.

[hswaters]

I thought it might help to include a link to a scan of the user manual that came with the Proma.

http://www.mediafire.com/folder/4fk7er8fwyr5v/Jorian

[hswaters]

So I thought I might as well update this.  I did connect all the grounds together and now I have control of the z axis from the cnc through the smartbob and also the Proma sd 50 controls the z axis when the torch is on.  I can now control the z axis when the torch is off.  The proma instructions were just right.