The term refers to the earliest DNC distributed cnc system, its meaning is a large-scale computer at the same time control of several CNC machine tools. Later, as the scientific and technological progress, by the NC NC system for the development of CNC, each CNC machine tools from a computer to control, so the concept of the past DNC has lost its significance. The CNC system has been very sound, generally support the RS-232C communication function, that is, through the RS-232口receive or send processing procedures, a lot of CNC system can be realized while receiving N / C side machining process, which is the so-called The DNC, but not all of the CNC system will support this feature, there are some systems only the first to receive the processing procedures stored in the system memory, but not at the same time cutting, this form of transmission is generally block transmission. Workshop existing cnc complex system, the system used by the communications between the procedures are different, resulting in between are not compatible with the status quo, To the technical staff, operators of the programming and application bring a lot of inconvenience and greatly limit the transfer of parts of the processing. NC part of the old system, memory space is limited, more than one procedure, the machine has enough memory space on a large number of processes had to delete and type of repeated and frequent repetition of parts ready to work a lot of work to waste time, direct Impact on the efficiency of CNC machine tools, processing procedures have repeatedly affected the process of stability. A unit of CNC machine tools may use a variety of numerical control system, in accordance with the traditional networking approach is generally to every machine equipped with a single PC machine, for different numerical control system using a different communication procedures, the drawbacks are obvious The. Workshop and put a lot of computers, poor industrial environment, greatly shorten the life of the computer, and clutter is not conducive to management. The CNC equipment is to super-integrated, intelligent, network-oriented development, increasingly pc computers and other advanced features, most of the current NC equipment in a single operation in the form of the same needs as pc , Network transformation and realize the sharing of resources. DNC communications software to support various cnc system, to support various communications standards.