The PCI/PXI/FW 7344 high precision controller can be used to control both steppers and servo motors. The older PC Step controllers are made for stepper only control. The difference in the two control types is with stepper control, the controller outputs two digital signals that control the step and direction of the motor. The drive uses these digital signals to energize the stepper phases and commutate the motor. In a servo system, the controller outputs a -10 to 10 Volt analog signal that the drive then uses to output the appropriate current to the motor which is proportional to torque.
You can get more information from the following website:
http://zone.ni.com/devzone/devzone.nsf/webcategories/69771825AE23E98E86256786000BEA02?opendocument
Please let u
s know if you have any further questions.
Regards,
Andy Bell
Applications Engineer
National Instruments