Definition of Direct numerical control

Direct numerical controlDirect Numerical Control (DNC)is a process set in a manufacturing unit where a set of machines are controlled by a programmed computer with the help of a direct connection to the same. It is based on real-time data and involves data collection from the machines and passing the same to the mainframe, at regular intervals. The operator will be in control of the mainframe computer through remote accesses. A DNC will not contain a tape reader. Instead, it has several part programs which is transferred to the machines from the computer memory. In few scenarios the machine controllers will not be able to store the entire program because of lack of memory space. In such situations, the program is stored in a different computer and the directions are sent directly to the machines from that location. The DNC is designed in such a way that it provides separate instructions to every machine on the system. In case, where the machine immediate control command, they are sent across immediately.

A DNC comprises of Mainframe computer, Huge memory capacity, Connectivity between the machines and the computers, and Machine tools.


  • It avoids the usage of punched taps and the reader from the system.
  • Helps the business to understand production performance by getting several reports and useful data from the machines.
  • Helps in building a centralised control for the machines.
  • Useful for time management and increased productivity.
  • Convenient storage of part programs in several computer files.

Types of DNC:

RS232 – based DNC system: Operates with a switch box or multi-port cable connections to connect several machines.

Terminal – based DNC system: A CNC terminal is created to connect several programs.

Network – based system: Direct access to NC programs without installation of terminals and is thus highly efficient.

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