Features: - Centronix-36 connector for standard LPT cable connection. - IDC-26 connector for DSUB-25 ribbon connection. - 4 x Open-drain Mosfet outputs for external relay control.. - 4 x RJ45 servo or stepper axis connections. - All 5 inputs optically isolated. - 1 analog output for VFD control. - Built in charge pump safety function. - LEDs on all in and outputs for easy visual debugging.. https://www.cncdrive.com/HDBB2.html