Nowadays, many packaging machines tend to be more and more automated. Therefore, the manufacturers pay more attention to the needs of customers when they are producing. Yongshun Shrinking Machine can help us better understand this type of machinery and equipment. For shrinking machines, When people use it, they must be more concerned about his degree of automation. PLC is now a more important control system.
The transformation of people's information is mainly realized by running programs stored in the PLC memory. This program is both systematic (this program, also known as the monitoring program or operating system), and the user. The system program provides the user program with an editing and operating platform. At the same time, it also performs necessary public processing such as self-test, I/O refresh, communication with peripherals, host computer or other PLC. The user program is set by the user according to the requirements of the control. What kind of control, what kind of user program.
Reliable physical implementation mainly through input (I, Input) and output (0, Output) circuit。 There is an I or 0 circuit for each input or output point。 Moreover, several such circuits are always integrated in one module (or box), and then 'integrated by several modules (or boxes) into PLC's complete I/O system (circuit)。 Although these modules are quite large and account for most of the PLC's volume, because they are highly integrated, the size of the PLC is still not very large。
The input circuit monitors the (ON, 0N or OFF, OFF) state of the input point and temporarily stores it in its input register (which may also have other names). Each input point has a corresponding input register.
The output circuit has output latches (which may also have other names). It also has two states, 髙, and a low state, and it can be latched. At the same time, it has a corresponding physical circuit that can send this high and low potential to the output. Each output point has a corresponding output latch.
The input registers and output latches here are actually registers of the PLC's I/O circuit. They exchange information with the PLC memory via the PLC I/O bus and the system program that runs the PLC.
The input register information is read into the PLC's memory, saying that the input is refreshed. The PLC memory has a dedicated mapping area for storing input information. Each corresponding bit in this area is called input relay, or soft contact, or process-image input register. These bits are set to 1 and Table 7K is open, # is 0, and the table currency contacts are broken. Since its status is obtained by refreshing the input, it reflects the status of the input point.
The output latches and the output mapping area in the PLC memory also correspond. An output latch also has a memory bit corresponding to it. This bit is called output relay, or output coil, or process-image output register. The status of the output relay is mapped to the output latch via the PLC I/O bus and the operating system program. The completion of this mapping is also called output refresh.
In addition to PLC input circuits that can receive switching signals, there are sometimes input circuits that receive analog signals (called analog input units or modules). Only the latter must first perform analog-to-digital conversion, and then store the converted data in the corresponding memory unit of the PLC.
To generate an analog output, an analog output circuit (called an analog output module or unit) is required. Relying on it, the contents of the PLC's corresponding memory unit are converted into digital and analog, and the output is generated.
In this way, the program that the user wants to program is only that the PLC loses the conversion from the memory area concerned to the output-related memory area. This is a problem of data and logic processing. Because PLC has a powerful instruction system, it is entirely possible to write a program that satisfies this requirement.