8 Organisation of the Modern Machine Control Unit Functions Control Program The

8 organisation of the modern machine control unit

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Figure 2.8 : Organisation of the Modern Machine Control Unit Functions Control Program The control program is that part which actually controls the various elements of the CNC machine tool. It has to take into account the interactions between the control system components, the machine tool mechanics, tooling, material changes during machining and other interactions that result in the final machine tool performance. It should analyze the part program a few blocks ahead so that the speed of the slides can be adjusted in advance to cater for future difficulties in the path (sharp changes in direction, tight radii). The control program should fully integrate with the servo and feedback systems involved. External Inputs This allows for interaction of the CNC with the outside world. For example to link with a PC for DNC functions such as part program downloading, remote datuming and operation so that it could be linked to integrated systems such as robots and automated guided vehicles (AGV), etc. External Outputs These are to send output from the CNC to outside world, for such tasks as uploading the generated or corrected programs, sending the controller information such as certain PLC register status, diagnostic information, etc. Program Memory It is to store the part programs and macros in the MCU for use. Earlier controls had very little such memory, but the current day controllers have much larger memory. With larger memory it is possible to store more programs as well as longer programs. Additional Programming Facility Better programming facilities can be provided in addition to the basic G and M-code programming as standardised by ISO. One such major area is in the provision of newer canned cycles to facilitate major machining of the components using simple programming. Some additional canned cycles as available in Anilam Controls is given below : Ellipse Spiral
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