Abstract : This paper introduces the working principle and main functional components of a CNC machine tool servo system using a digital pulse comparator. Keywords : CNC machine tool; servo system; digital pulse In the position control servo system of a CNC machine tool, the digital pulse method is used to form a closed-loop position control, which has a relatively simple structure. A photoelectric encoder is used for position detection, and the position is constructed in a semi-closed-loop control structure to form a pulse comparison servo system. 1. Composition of the Digital Pulse Comparison System This system can consist of up to 6 main components. As shown in Figure 1: 1.1 Command Signal: The command signal provided by the CNC device can be a digital signal or a pulse digital signal. 1.2 Feedback Measurement Signal: The feedback signal provided by the measuring device can be a digital signal or a pulse digital signal. 1.3 Comparator: A comparator that compares the command signal with the measurement feedback signal. 1.4 Pulse: A component for converting between pulse digital signals and digital signals. 1.5 Drive and Actuation Elements: This part is essentially a speed unit and a motor, which drives the worktable to move according to the output of the comparator. Since the command and feedback signals may not necessarily meet the comparison needs, additional components are sometimes needed between the command and comparator, and between the feedback and comparator. The circuit is a "digital pulse to digital conversion". The comparator output reflects the difference between the command signal and the feedback signal, as well as the direction of the difference. This output signal is amplified and then used by the speed unit to control the actuator. [b][align=center]For more details, please click: CNC Machine Tool Servo System Using Digital Pulse Comparator[/align][/b]