In the system of NEMA 34 stepper motor driver, the micro adjustment capacitor and coupling ring are all driven by stepping motor. The fundamental control method of fmstepmove is to select RS-422 standard differential pulse.

When the step is running, the step pulse is announced by i/o port of industrial control computer; During continuous operation, i/o port of industrial control computer announces continuous pulse enabling signal, and connects the oscillator on the driving pulse attack circuit to connect pulse output. Step or continuous pulse signal is converted into square wave with duty cycle of 50% by single stable trigger. It is driven by differential driver of RS-422 specification to NEMA 34 stepper motor driver to drive the stepping motor movement.

The key point of the fine tuning capacitor is to ensure the step accuracy (step resolution). According to the requirements of fine tuning the lead and small step distance of the capacitor ball screw, the fmstepmove subdivision is set to 10000 subdivision / rotation (step distance 0.036b), and two pulses (equivalent to 0.4um linear displacement) are used as the cycle step.

In practice, when the fine tuning capacitor needs to be step driven, the system industrial control machine announces two pulses successively through its i/o port in each cycle cycle, and drives the motor to move step (0.4um) through the NEMA 34 stepper motor driver. The rotation and stop of the stepper motor are determined according to the practice of the linear orientation reaction of the fine-tuning capacitor linear induction synchronizer until the end of the step motion.

When the driving key is pressed, the industrial control computer announces the continuous pulse enabling signal through the i/o port, turns on the connected pulse output of the oscillator, and the NEMA 34 stepper motor driver drives the step motor to connect the motor. After the drive key is released, the industrial control computer will close the pulse enabling signal through i/o port, and the stepping motor will stop rolling and finish the continuous driving operation.