PLC digital analog quantity analogy - Solutions - Huaqiang Electronic Network

Supply 1206 blue light 1206 blue LED quality assurance original authentic large number

Photocoupler

Switching quantity: The switching quantity has only two states, 0, 1, including the opening amount and the opening quantity, reflecting the state.
Digital quantity: A digital quantity consists of multiple switching quantities. For example, three switching quantities can form a digital quantity representing eight states.
Analog quantity: The analog quantity is a continuous quantity, and the digital quantity is discontinuous. Reflected in the electricity measurement values ​​(such as current, voltage).
1. Switching quantity: for on-off signal, passive signal, resistance test method is resistance 0 or infinity;
It can also be an active signal. The professional name is a step signal, which is 0 or 1. It can be understood as a pulse quantity moderator saying that a plurality of switching quantities can form a digital quantity.
2. Digital quantity: A signal type consisting of 0 and 1 is usually a coded regular signal. The relationship with the analog quantity is the quantized analog quantity.
3. Analog quantity: continuous voltage, current and other semaphores. The analog signal is a signal whose amplitude changes continuously with time. After sampling and quantification, it is a digital quantity.
4. Pulse amount: A signal quantity that changes from a certain value to another value at an instantaneous voltage or current. After quantification, the continuous regular change is the digital quantity. If it changes from 0 to a fixed value and remains unchanged, it is the switching quantity. The switching quantity mainly refers to the opening quantity and the opening quantity, which refers to a device. Auxiliary points, such as the auxiliary point of the relay of the transformer's thermostat (the transformer is displaced after over-temperature), the auxiliary point of the valve cam switch (displacement after the valve switch), the auxiliary point of the contactor ( After the contactor is displaced, the thermal relay (displacement after the thermal relay is activated), these points are generally transmitted to the plc or the integrated protection device. The power supply is generally provided by the PLC or the integrated protection device, and it does not have its own power supply. Called passive contact, also called PLC or integrated protection device.
The digital quantity is defined as a discrete signal that is intermittently varying in time and value.
The analog quantity is defined as a signal that is continuously changing in both time and value.
The most basic digital quantity is 0 and 1. In the most basic sense, it means that the switch is the open (0) or closed (1) state of a switch. The switch quantity is passive, that is, it requires the device output power pair. It performs the test (this is also the amount of input of the device, such as the non-electrical input of the integrated protection device is an externally provided input amount); it can also be encoded with 0 and 1 to compile various communication codes.
The analog quantity refers to the voltage, current, frequency and other power signals transmitted by PT, CT, etc.; the pressure sensor passes the pressure transmitter, the liquid level sensor through the liquid level transmitter, the flow sensor through the flow transmitter, the thermocouple or The 4-20 mA (electrical type III meter) signal transmitted by the thermocouple via a temperature transmitter or the like is an analog quantity. The comprehensive protection device can detect the amount of electricity (voltage, current, frequency, etc. transmitted by PT, CT, etc., that is, analog quantity) and non-electrical quantity signal (light gas, heavy gas, over temperature signal of the transformer, that is, non-electricity, that is, Switch opening and closing)
Switching quantity, digital quantity, pulse quantity.
1. The measured quantity and analog quantity are directly measured.
Switching quantity: reflects the status signal (such as switch on and off).
Analog quantity: reflects the electricity measurement value (such as current, voltage).
2. The pulse quantity is generally the integral quantity (such as electrical measurement), which cannot be directly measured, and needs to be calculated by the measuring instrument.
3. The measured switching quantity, digital quantity, and pulse quantity are modulated, digitally encoded, and transmitted in the communication channel.
Previously, analog signals were also used for transmission. Nowadays, digital signals are generally used for transmission.
4. The dispatcher demodulates the signal and restores the information.
It is clear that the digital and digital signals are clearly separated. The digital quantities are analog and analog.
The amount of switching and the amount of pulses are all physical quantities whose digital signals are discrete in time and quantity. The signal representing the digital quantity is called a digital signal. E.g:
When an electronic circuit is used to record the number of parts output from the automatic production line, each time a part is sent, a signal is given to the electronic circuit to record 1, and the signal applied to the electronic circuit when there is no part to be sent is 0, which is a count. It can be seen that the number of parts is a signal that is discontinuous both in time and in number, so it is a digital signal. The smallest unit of quantity is one.
A physical quantity that is continuous in time or numerically is called an analog quantity. The signal representing the analog quantity is called an analog signal. E.g:
The voltage signal output by the thermocouple during operation is an analog signal, because the measured temperature is unlikely to jump in any case, so the measured voltage signal is continuous in both time and quantity. Moreover, any value of this voltage signal in the continuous change process is a specific physical meaning, that is, a corresponding temperature.
1. A digital quantity whose quantity is discrete in both time and quantity is called a digital quantity. The signal representing the digital quantity is called a digital signal. An electronic circuit that operates under a digital signal is called a digital circuit.
E.g:
When an electronic circuit is used to record the number of parts output from the automatic production line, each time a part is sent, a signal is given to the electronic circuit to record 1, and the signal applied to the electronic circuit when there is no part to be sent is 0, which is a count. It can be seen that the number of parts is a signal that is discontinuous both in time and in number, so it is a digital signal. The smallest unit of quantity is one.
2. The analog quantity is a continuous physical quantity in time or numerical value called analog quantity. The signal representing the analog quantity is called an analog signal. An electronic circuit that operates under an analog signal is called an analog circuit.
E.g:
The voltage signal output by the thermocouple during operation is an analog signal, because the measured temperature is unlikely to jump in any case, so the measured voltage signal is continuous in both time and quantity. Moreover, any value of this voltage signal in the continuous change process is a specific physical meaning, that is, a corresponding temperature.
The switch quantity includes the amount of opening and the amount of opening, which is a digital signal. There are only two states, 0 and 1, indicating the closing or opening of the relay contacts or the auxiliary contacts of some circuit breakers. The opening amount is the signal input of the protection device, and the position information such as the field switch and the knife gate are collected.
The amount of opening and opening in the microcomputer protection refers to the digital quantity, that is, the closing or opening of the relay contacts or the closing and opening of the auxiliary contacts of some circuit breakers.
Specifically, the amount of switching input into the microcomputer protection is the amount of opening, and when the microcomputer protects the CPU control unit from issuing an instruction, the relay closes or disconnects the output to the device.