Adopting latest DSP control technology and advanced stepper control algorithm complete control for 4 axes. Each axis can have its own configurations Step & direction control 20-60 VDC supply voltage Output current from 1.45 to 6.0A per axis 8 micro step settings: 1, 1/2, 1/4, 1/8, 1/10, 1/16, 1/32, 1/64 8 output current settings: 1.45, 2.08, 2.72, 3.37, 4.05, 4.72, 5.35, 6.0 A Built-in breakout board 5 digital inputs, 4 general outputs, & one 0-10 VDC analog output DIP switches for micro step and output current configurations Anti resonance for low and middle speed Excellent high speed performance Extra low motor heating & noise; smooth movement Able to drive NEMA 17, 23, 24, and 34 stepper motors Built-in breakout board with DB25 connector and IOs for easy setup with many CNC control systems such as Mach3 and EMC Easy to install and simple to implement Automatic idle current reduction to 50% The MX4660 adopts a more flexible design for its Input1-4 for proximity sensors with different rated voltages. The power input for the opto-couplers for these four input(input1-4) is configurable via OPTO1 and OPTO2. Which means you need to connect power supply to these two pins (OPTO1 and OPTO2) to make these four inputs work normally. By the way, Input5-8 use the same design as the MX3660 (12VDC sourcing, 10 mA max) because of the size limitation.