Three kinds of PLC in CNC lathe factory, a CNC system information exchange technology
Three kinds of PLC in CNC lathe factory, a CNC system information exchange technology release date: 2017 - 11 - 24 clicks: 2526 times in the numerical control lathe numerical control system, CNC and PLC are logically independent functional unit. The information exchange based on PLC as the center, in CNC, PLC and CNC machine tool of information transmission between. CNC will all sorts of function code information M, S, T, manual/automatic mode information, enabling information sent to the PLC. And the PLC will M, S, T reply point of reference for the signal and the corresponding coordinate axis machine tool information to CNC, etc. Actuators of PLC and control machine tools and various states send machine tool fault diagnosis and alarm instructions and other information. On the operation panel and the machine will each switches, buttons and other signals, and the moving parts of limit information sent to the PLC. A, external PLC information exchange external PLC is a general-purpose PLC, it is completely independent of the CNC device, has perfect hardware and software, can independently accomplish logic sequential control task. CNC and PLC has its own switch I / 0 interface circuit, PLC I / 0 points and function according to the complexity of the auxiliary motion of the nc machine tools. In the use of an enterprise CK6150 nc lathe system replacement, adopt the original plus external Siemens S7 - FAGOR8025 numerical control system Type 200 PLC maintenance scheme. The PLC CPU226 ( 24 v dc lose / 16 relay output) Main unit, extension EM221 ( 8 in) 24 v dc lose into the unit and EM222 ( 8) Relay output units 56 programmable controller. PLC output were used to control the spindle speed, cooling oil pump, tool carriage motor, lubrication, hydraulic chuck, hydraulic tailstock and produce all kinds of control instructions, and other functions. Second, the built-in PLC type information exchange within the PLC type also known as the built-in PLC, all of its functions in CNC internal, and CNC integrated into an organic whole. The basic function of the PLC hardware and software for CNC the same design, its performance index is to determine by CNC system. Signal transmission between PLC and CNC other devices within the system, PLC switch quantity output by CNC I / 0 circuit is complete. The PLC can be Shared between CNC CPU, also can set up a dedicated CPU, respectively. Shared CPU is can make full use of the resource of the microprocessor in CNC equipment, but when the PLC I / 0 points too much, can affect the function of CNC processing speed, CNC system is commonly used in the medium. Using special CPU to complete the function of PLC, speed, used in large scale and complex logic and action in the high speed CNC system. Because of the built-in type PLC and CNC internal data bus is used to process information, makes data processing ability, the external wiring is simple, high reliability. Three, open numerical control system of PLC with the rapid development of the computer technology to quit, a large number of advanced high performance computer be directly used for the control of the CNC system. Based on high performance industrial control computer ( IPC） As the core of the open structure become the main direction of numerical control system development. In the preservation, on the basis of traditional CNC system, added more other functions of the computer system. Built-in soft PLC is often used to form the PLC, PLC program development generally use a high-level language. Numerical control system in the initialization time according to & other; plc。 h” The provisions of the header files, in the storage area for PLC defines the internal transfer from NC to PLC lost into the read-only state variables, and internal output variables by PLC to NC. The state variables are NC module in the process of running the numerical control system and save the running state of machine tool, the data can be for the use of NC module in the process of running and modify, if you need to call in the operation of the PLC module in these variables, are done in read-only mode. State variable access format specified in the numerical control system development, write PLC program should be carried out in accordance with the prescribed format. Due to using a high-level language programming, compared with the traditional ladder diagram programming methods, such as increased the complexity of the programming, but significantly increased flexibility of programming, and makes the system function more powerful. In the PLC control program need to carefully read details of numerical control system of PLC.