Introduction to Mitsubishi PLC memory classification

Mitsubishi PLC's Memory is a memory device in the measurement muscle system that is used to store processes and data. The overall information in the measuring machine, including the output of the original data, the measuring machine process, the central operating cut-off and the final operating cut-off are stored in the memory. It deposits and takes out information in the direction specified by the controller. The following will briefly talk about the characteristics of several types of memory of Mitsubishi PLC.

Introduction to Mitsubishi PLC memory classification

Introduction to Mitsubishi PLC memory classification

Composition of the memory:

At that time, semiconductor materials and magnetic materials were mainly used as the storage medium that made up the memory. The smallest preservation unit in the memory is a bistable semiconductor circuit, or a CMOS transistor, or a storage element of a magnetic material, which can hold a binary code. A preservation unit is formed by a single preservation element, and then a storage unit is formed by many preservation units. A memory contains a number of save units, each of which can hold one byte. The direction of each preservation unit is numbered, i.e., local, and the whole is indicated in hexadecimal. The sum of the data that can be stored in a full storage unit in a memory is called its storage capacity. Assuming that the local code of a memory consists of a 20-bit binary number (i.e., a 5-digit hexadecimal number), 220 can be indicated, i.e. 1M storage unit locals. Each save unit registers one byte, then the storage capacity of this memory is 1KB.

There are three types of storage classifications:

1. Random memory

Random access memory (RAM), also known as "random access memory", is the internal memory that directly exchanges data with the CPU, also known as main memory (memory). It reads and writes at any time, and it's fast, and it can be used throughout the operating system or other running processes to save temporary data.

RAM features

Random access. The so-called "random access" refers to the fact that when the data in the memory is read or written, the time required is not closed to the direction in which the information is written or written. On the other hand, when reading or writing information in a Sequential Access device, there is a close connection between the time and direction of the information required. It is mainly used to host the operating system, various application processes, data, etc.

Volatile. RAM is not able to save data when the power is blocked. If data needs to be stored, it must be written to a solid-state random access memory (e.g. a hard disk) for a permanent storage device. RAM and ROM comparison, the biggest difference between the two is that the data stored on the RAM will actively disappear after the power is off, while the ROM will not actively disappear, so it is okay to save it when the power is off.

Sensitive to static electricity. Like other tight integrated circuits, random-access memories are exceptionally sensitive to the electrostatic charge of the condition. Static electricity can disturb the charge of the capacitors in the memory, resulting in data loss and even burnout of the circuit. Therefore, before touching the random access memory, you should first ground the metal with your hand.

Visit speed. The novel random access memory is simply the fastest write and read speed in a very fast access facility, and the access delay notebook computer memory is also negligible compared to other save devices that touch the lag operation.

Requirement rewriting (regeneration). The novel random access memory holds data with capacitors attached. Capacitors are covered with electric heirs in Table 1 (binary), and uncharged represents 0. Because capacitors or many climates where leaks may be rare, data can be lost over time if not specifically disposed of. Rewriting refers to the situation of reading the capacitor on time and then recharging the capacitor according to the original situation to replace the lost charge. Demand Rewriting Zhengjia proves the volatile nature of random access memory.

2. Read-only memory

Read-Only Memory (ROM). The data stored in the ROM is pre-written before loading the whole machine, and can only be read during the course of the whole machine, and it is not quickly and easily rewritten like random memory. The data stored in the ROM is stable, and the data stored in the ROM will not be converted after the power is off; Its structure is large and easy to read, so it is often used to save various fixation processes and data.

Read-only memory characteristics

Read-only memory is characterized by the fact that it can only read out and cannot write information at will, and a fundamental output/output system called BIOS (Fundamental Output Output System) is solidified in the ROM on the motherboard. Its main efficiency is to end the power-on self-test of the system, the initialization of each effect module in the system, the activation process of the system's fundamental output/output, and the leading operating system.

3. External memory

External reservoirs are reservoirs other than the memory of the estimator and the slow memory of the CPU, which can still hold data even after a power failure. Rare external storage includes hard disks, floppy disks, optical discs, USB flash drives, etc.

Introduction to Mitsubishi PLC memory classification

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