Mitsubishi PLC and computer communication connection - Database & Sql Blog Articles

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Due to the high performance and high reliability of plc, it has been widely used in industrial control field, and has evolved from simple logic control to multi-function controller integrating logic control, process control, servo control, data processing and network communication functions. . Since the PLC itself does not have a display function, it is important to realize its internal data display, and it becomes a difficult point in the design of the PLC control system.

In the PLC control system, the contents to be displayed mainly include timer value, counter value and data register value. The data display method can be summarized into two basic types: one is based on PLC data communication interface, such as RS-232, RS- 485/422, the display device also has such an interface, and data display is realized by data communication.

Communication-based data display technology

Data transmission and display using data communication interface is an effective way to realize PLC data display. At present, mainstream PLCs provide standard RS-232 or RS-485/422 interfaces, or add such interfaces through module expansion.

The communication modules 232ADP, 232BD, 485BD and 485ADP of Mitsubishi FX2N can be used as data interfaces. The display device can be equipped with a dedicated intelligent display screen and a general-purpose computer (PC). Directly select the display screen or touch screen matched with the PLC, which can realize centralized display of multiple data inside the PLC, and can edit the screen graphics with the editing software to improve the display interface. Visibility. The FX series can be equipped with F93000T-BWD, F940GOT-LWD and F940GOT-SWD. The intelligent display reads the PL registers through the communication interface, and the data display efficiency is high, and the design of the control system can be simplified. However, due to the high cost of the display, the application of the large-size display is limited, so the method is suitable for a compact PLC control system. With the further improvement of computer performance and reliability, the control system of "PC+PLC" mode has been widely used in the field of industrial control. With rich software and hardware resources, PC can realize on-line monitoring of PLC and display a large number of PLC internal data. The dynamic process flow and data trend curve of the control device can be displayed in a graphical manner, so that the human-machine interface of the system is intuitive and friendly.

PLC and group Taiwang communication connection

1:1 one station, distance <15 meters, driven by programming port

Communication via programming port (plc does not require programming)

1:N multiple stations (up to 16 stations), 50 meters > distance > 15 meters, driven by FX485

1:N multiple stations (up to 16 stations), 500 meters > distance > 50 meters, driven by FX485

1: N multiple stations (up to 16 stations), 1200 m > distance > 500 m, driven by FX485 (plus 485 relay)

The RS485 connection can be one or two pairs of wires. According to the purpose of determining the connection method, this design uses two pairs of wire connections.

In order to establish the communication connection between the PLC and the group Taiwang, the communication address and communication parameters can be set in the menu "PLC/serial port setting" of the plc programming software, or directly in the software by programming (MOV instruction). The specific settings of RS485 are:

The baud rate is set to 9600 bit/s, the data bit is set to 7 bits, the l bit start bit, the 2 bit stop bit, even parity, and protocol 1. Set with the programming software, where the communication address is set in D8121.