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Programming controller (programmable controller)
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Programming controller (programmable controller) abbreviated as PLC, where l, logic, first can programming controller is 1969 available in the United States. After 30 years of development, it has become the most important, the most reliable and the most widely used industrial control microcomputer. Programmable controller is a digital computing operation of electronic systems, designed for applications in industrial environments designed; it uses a kind of programmable memory for storage of its internal procedures, perform the logic operation, sequence control, timing, counting and arithmetic operation etc. user oriented instruction, and through digital or analog input / output control various types of machinery or production process. Programmable controller and its related external devices are designed to be integrated into a whole, easy to expand its function in accordance with the industrial control system. Programmable controller has many advantages: (1) PLC manufacturers are focused on improving the reliability of the indicators. (2) PLC also has the advantages of easy programming, easy to use. (3) PLC control function is very strong, in addition to the basic logic control, timing, counting and arithmetic operations and other functions, with special function module, position control, PID operation, process control and digital control function can be realized, is convenient for factory management and communication with the host computer and the remote module can control the remote device. (4) the extension of the PLC and the extremely convenient connection with the external. So can each parameter of the programming controller is applied to the radio transmitter can realize broadcast transmitter automatic switch machine, and collect and monitor transmitter, abnormal state of alarm, backup can realize automatic reversing backup. It can real-time transmitter found abnormal, timely treatment, reduce the broadcast rate, can very good assurance program of safe and high quality broadcast, and can greatly reduce the transmitter's duty.
To use PLC to realize the automatic control of broadcast transmitter, to take full account of many factors, in my development "of DX-600 MW Transmitter automatic control system as an example, I will the whole system design is divided into the following four steps.
First to determine the control and surveillance of PLC. Analysis of transmitter to monitor indicators, as well as automatic control operation, such as incident power sampling, reflection power sampling, water level sampling, power sampling, switch on the mobile phone operation, shutdown operation, power operation, reduced power operation. The number of sampling points and the control range are determined by the transmitter. And then choose the appropriate PLC, on the one hand, choose the PLC of the capacity; on the other hand, what the company's PLC and peripheral equipment. For the first question, we must analyze the transmitter in detail, and find out all the I / O points, including the / I / O / I / O and the properties of these points. The nature of the I / O points mainly refers to them is AC or DC signal signal, voltage, sampling points or the output of the control point, the output is relay type or a transistor or controllable silicon type. After that, you can set the number of points and I/O is what the nature of the PLC. For the second issue, there are the following aspects: A, functional aspects. B, price. After the host of the programmable controller is selected, it is generally to choose the analog data acquisition module, and the number of modules is determined according to the amount of simulation. Display setting unit depending on whether or not. In this case "of DX-600 MW Transmitter automatic control system, through the analysis the system requires 17 road switch output, 11 road switch input, 6 analog acquisition. So the SIMATIC S7 - 226 type PLC, two fast em - 23 analog acquisition module. SIMATIC S7226 24 channel switch input and 16 switch output, each EM-231 support 4-way analog input point, two is equivalent to 8 channels analog inputs, fully able to meet the needs of the system and future system expansion upgrade to stay in space.
2, I O / PLC address allocation
The address allocation of the input / output signal on the PLC terminal is the basis for the design of the PLC control system. For the software design, I / O address assignment can programming; for PLC external wiring, only after determining the I / O address before they can draw the electrical wiring diagram, assembly drawing. The distribution of I / O address is best to assign a similar signal point to a continuous I / O address, while the O / I point name, code and address are listed in the form of a table.
3, transmitter monitoring system hardware and software design
System design includes hardware design and software system design. Hardware system design mainly includes the design of PLC and peripheral circuit, electric circuit design, etc.. Software system design mainly refers to the preparation of PLC monitoring program, some systems also include the preparation of the host computer program, for example, in this case, including the PC program. System hardware design is mainly design principle diagram of electric control system, electrical control components, here hardware design is described in detail, mainly to everyone described steps and the process of software design. In the PLC program design, in addition to the I / O address list, but also the used in the program of intermediate relays, timers, counters (PLC soft component) and a storage unit and their function of column write out, so that the program to write and to read. The following combination and I developed the "DX-600 MW Transmitter automatic control system" describes in details the radio transmitter automatic control system PLC program is compiled and debugged.
Siemens S7200CPU programming software for the V3.1 STEP 7 MicroWIN SP1. The software
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