The Proxxon Type CU 4 Control Unit is compatible with the MF 70/CNC-ready, FF 500/BL-CNC-ready, PD400/CNC-ready and for universal use. It has been designed for controlling the step motors of CNC machine tools. The PROXXON CU 4 CNC control unit handles the communication between the computer running the control software and the drives of the CNC machine. It converts the “path information” transferred to it by the computer into path commands for the drives of the axes and into commands for switching the spindle drives of the processing machine. The choice CNC-software is free: e.g. MACH3/4, Estlcam may be used for operation via parallel-port (if necessary with use of LPT-adaptor).

The CU 4 control unit is equipped with four driver stages enabling it to control a maximum of four axes of a machine tool. The drives are connected to the driver stage via Sub-D9 sockets located at the rear of the housing of the control unit, which are marked with the letters z, y and x. There is an additional socket marked with the letter U for controlling instruments such as positioning heads or dividing heads.

The CU4 is connected to the control computer by a DB25 socket via a breakout board. The breakout board functions as an optocoupler for purposes of the electrical separation between the control computer and the control unit, thereby protecting the control computer against potentially hazardous voltage spikes emitted by the control unit.

The rear side of the unit features two sockets, one for a mains plug and the other for a Type F plug. These can, for instance, be used for connecting the drive of the machine tool used, a cooling pump or extraction device and, if required, for controlling them by means of the CNC software running on the computer. For this purpose, the two sockets are connected in parallel.