1 Introduction: CNC machine tool is a high-efficiency mechatronics equipment, which has been widely used in various manufacturing enterprises. In the application, the transmission of data using RS-232C serial port is an important part. The RS-232C interface has a 9-pin or 25-pin serial port on the CNC machine. Its features are: simple, connected by an RS-232C cable and a computer, which can realize system parameters and processing procedures between the computer and the CNC machine. PLC program, tool compensation and other data transmission; complete data backup and data recovery; DNC processing and diagnostic maintenance. 2, RS-232C communication overview: 2.1 RS-232C Definition: RS-232C is a serial physical interface standard developed by the Electronic Industry Association (EIA). RS is an abbreviation of the English "recommendation standard", 232 is the identification number, and C is the number of revisions. The data transmission rate specified by the RS-232C standard is 50, 75, 100, 150, 300, 600, 1200, 2400, 4800, 9600, 19200 baud per second. According to the RS-232C standard, the driver is allowed to have a capacitive load of 2500pF, and the communication distance will be limited by this capacitor. For example, when using a 150pF/m communication cable, the maximum communication distance is 15m; if the capacitance per meter is reduced, communication The distance can be increased. Another reason for the short transmission distance is that RS-232C is a single-ended signal transmission, which has common ground noise and cannot suppress common mode interference. Therefore, it is generally used for communication within 20m. 2.2 Electrical Characteristics of RS-232C Interface: The voltage of any signal line in RS-232C is negative logic relationship. Namely: logic "1", -5 - -15V; logic "0" +5 - +15V. The noise margin is 2V. That is, the receiver is required to recognize signals as low as +3V as logic "0" and signals as high as -3V as logic "1" 2.3 Physical structure of RS-232C interface: Some devices are connected to the RS-232C interface of the PC. Because they do not use the transmission control signal of the other party, only three interface lines are required, namely “send dataâ€, “receive data†and “signal groundâ€. ". Therefore, the DB-9 9-pin connector is used, and the transmission line is shielded twisted pair. At present, DB-25 type connectors are rarely used in CNC machine tools, and DB-9 type connectors are generally used. 2.4 RS-232C pin assignment (DB-9): see the table below The following is a description of the serial port application of the new CNC system M7 series introduced by Mitsubishi. 3, M7 series serial port classification and function: 3.1 M7 series CNC system classification: M7 series CNC system is divided into three categories: 1) M70 series; 2) M700 series; 3) C70 series. As shown below: The above CNC series is currently the latest CNC system being introduced by Mitsubishi. 3.2 M7 series CNC system serial port classification: The following table shows the M7 series serial port name and serial port classification: From the above table, we can see: The M70 series has only one serial port SIO, which consists of channel 1 and channel 2. The serial port of the M700 series is divided into a display unit serial port (SIOPC) and a control unit serial port (SIO), which are also composed of channel 1 and channel 2, respectively. The C70 uses USB and IC cards when communicating with external devices. There is no serial port function. The following describes the wiring method of the serial port as follows: 3.2.2 M700 series serial port SIO connection cable and wiring diagram are the same as M70 series serial port; M700VS serial port SIO1 and SIO2 connection cable and wiring diagram are the same as M70 series serial port, SIO1 and SIO2 function and usage are the same. 3.2.3 M700 series serial port SIOPC (except M700VS) connection cable and wiring diagram: Next page Pc Sheet,Frosted Pc Sheet,Polycarbonate Hollow Sheet Fenghua Jade Motor Co., Ltd. , http://www.hypcsheet.com
