Question 2: What does the analog input of frequency converter mean and how to connect it? Like this, it can be used for frequency converter speed regulation, pressure input of constant pressure water supply, and so on. To put it bluntly, this value is input to determine the output frequency of the inverter, which can be directly proportional or inversely proportional.
Question: What do digital and analog mean in the input selection displayed by AOC? One is a digital signal, and the other is an analog signal. Analog is converted from digital, and the conversion process is necessarily different, while digital is directly output (DVI) without conversion.
Moreover, there are three types of DVI, which can be found online.
There are two kinds of DVI-I analog digital.
Digital video interface
DVI-A simulation (rare)
Digital signal quality is better.
Question 4: The difference between analog input and digital input. Analog input and digital input refer to different types of input signals.
Signal data can be used to represent any information, such as symbols, characters, sounds, images and so on. , can be divided into analog signals and digital signals. The difference between analog signal and digital signal can be determined according to whether the amplitude value is discrete or not.
Analog signal means that the amplitude value is continuous (amplitude can be expressed by infinite value). Time-discrete analog signal is a kind of sampling signal, which is obtained by sampling the analog signal every t. Although its waveform is discontinuous in time, its amplitude is continuous, so it is still an analog signal, which is called pulse amplitude modulation (PAM) signal. Usually, the sound we hear and the TV images we see are analog signals.
The conversion from analog signal to digital signal generally goes through three processes: sampling, quantization and coding, and finally becomes a series of pulse digital signals represented by 0 and 1. Digital signals were first used in communication, which triggered a revolution in the field of communication.
1. Analog communication: The advantages of analog communication are intuitive and easy to realize, but it also has important disadvantages.
(1) has poor security.
Analog communication, especially microwave communication and wired communication, is easily eavesdropped. As long as the analog signal is received, it is easy to get the communication content.
(2) Weak anti-interference ability
In the process of electric signal transmission along the line, it will be interfered by various noises inside and outside the communication system, and it is difficult to separate the noise from the signal after mixing, thus reducing the communication quality. The longer the line, the more noise is accumulated.
Everyone has experience: every time you copy tapes and videos, the quality of sound and images is poor, which is why.
2. Digital communication system
Advantages of (1) digital transmission and exchange
① The confidentiality of communication is strengthened. After A/D conversion, the voice signal can be encrypted first, then transmitted, decrypted at the receiving end, and then restored to analog signal through D/A conversion.
② Anti-interference ability is improved. Digital signals will be mixed with noise during transmission. The input signal voltage can be measured by mosfet (called threshold) composed of electronic circuits. Only when the voltage reaches a certain amplitude, the circuit will have an output value and automatically generate neat pulses (called shaping or regeneration). When the small noise voltage comes, it will be filtered out because it is lower than the threshold value, and it will not cause circuit action. Therefore, the regenerated signal is exactly the same as the original signal, and only when the interference signal is greater than the original signal will an error code be generated. In order to prevent the error code, the method of error detection and correction is set in the circuit, that is, when the error code occurs, the opposite party can be retransmitted by using the reverse signal. Therefore, digital transmission is suitable for long-distance transmission and lines with poor performance.
③ A complete digital communication network can be built. After adopting time division switching, transmission and switching are unified, and a complete digital communication network can be formed.
(2) Disadvantages of digital communication
(1) occupies a wide frequency band. Because the line transmits pulse signals, it needs 20-64kHz bandwidth to transmit digital voice information, while an analog voice channel only occupies 4kHz bandwidth, that is, a PCM signal occupies several analog voice channels. For a certain telephone line, its utilization rate has decreased, or its requirements for the line have increased in detail.
② The technical requirements are complex, especially the synchronization technology requires high precision. If the receiver can correctly understand the meaning of the sender, it must correctly distinguish each symbol and find the beginning of each information group, which requires strict synchronization between the sender and the receiver. If a digital network is formed, it will be more difficult to solve the synchronization problem.
③ The analog-to-digital conversion will bring quantization error. With the use of large-scale integrated circuits and the popularization of broadband transmission media such as optical fiber, more and more digital signals are used for information storage and transmission, so analog signals must be converted from analog to digital, and quantization errors will inevitably occur in the conversion.
After the communication is converted from analog to digital, the benefits are well known: in the past, when the analog crossbar switch was used, the connection rate between a local telephone office was less than 20%, and when the rural cable broadcasting was opened, the rural telephone could not be called, all of which were interference sounds ... After using the all-digital program-controlled switch and digital transmission circuit, the telephone connection rate was greatly improved, and the transmission quality was almost inaudible, forming a local area with prefecture-level cities as the unit. Electricity in a few years ... >>
Question 5: Digital input, output and analog input. What do you mean by output? Digital inputs and outputs are binary values. 1 if the switch is on, and arc if it is off.
For example, the analog input is the temperature value collected by the temperature sampler and must be converted into a binary number that can be recognized by PLC by the transmitter.
The analog output is just the opposite. Data transmitter actuator
Question 6: PLC, what is analog input and what is digital input voltage and current? This signal is analog.
The status bit of switch signal 0 1 is a digital double call switch!
Question 7: What is the meaning of analog input in the inverter specification? Refers to the input signals of 0~ 10V, 2~ 10V,-10V~+ 10V, 0~20mA or 4 ~ 2ma.
Used as a given input signal.
Question: What does the analog input and output of PLC mean? Thank you. To understand this, you must first know two things:
1. The analog instruments used in our field convert signals such as pressure, liquid level and temperature into 1-5V and 4-20mA (there are other signals, such as 0- 10V and 0-5V, etc.). ) and then hand it over to PLC for processing.
2.PLC doesn't know the size of the specific voltage or current signal.
So we need to use a number to represent its size, and then tell PLC to know how big the input voltage and current signal is.
For example, the temperature we are measuring now is 20 degrees (the range is 0-50 degrees and the output range is 1-5V). At this time, the voltage generated by the temperature sensor is (5- 1)*20/50= 1.6V (the instrument characteristics must be linear to calculate this). After receiving the input of 1.6V, the analog input module of PLC will convert it into digital quantity. For example, the resolution of the analog input module we use is 0-4000 corresponding to 1-5V. Then, 2.0V should correspond to (4000-0)/(5-1) *1.6 =1600. That is to say, after reading the number 1600 given to it by the analog input module, PLC can know that the temperature sensed by the temperature sensor is 20 degrees.
In the above example, the range and output range of the sensor are determined by the sensor. The resolution of the analog input module is determined by the analog module. The function of analog output module is just the opposite of that of input module. Used to convert digital information into 1-5V and 4-20mA.
In addition, there are many methods of digital-to-analog conversion, and you can search related information through Baidu.
Personal opinion, I hope it will be useful to you.
Question: What do analog input and output and digital signal input and output mean in plc? I hope I can make it easy to understand. I just learned it. Thank you very much. The answer is simple:
Digital signal input and output: that is, the switch is closed and opened.
Analog input and output: numerical values, such as liquid level 1.5m, temperature 30 degrees, and so on.
Question 10: What does analog VGA mean? Analog interface
It is ridiculous to input analog signals into TFT-LCD display devices for display. All the data running in the computer, including image information, are converted into analog signals on the graphics card, and then transmitted to the display through the connecting line, and then displayed on the display in the form of digital signals. If this is done, it is completely unnecessary. In addition, the consequences of doing so are very obvious. On the one hand, it increases the extra hardware overhead, on the other hand, there are inevitable losses in the process of signal conversion, which ultimately affects the quality of displayed images. Therefore, the digital signal interface is suitable for LCD. However, the actual situation in the market is not entirely the case. At present, most liquid crystal displays in the market still use analog signal interfaces, and the fundamental reason is that the specifications and standards are inconsistent.