Description
Digital input and output signal is the switching signal, 0 or 1, analog signal, there are two, voltage or current signal, generally the signal transmitted by the transmitter, such as the pressure transformer to detect the pressure of the water pipe, it will output an analog signal 4-20ma or 0-10V signal to the PLC, PLC for data processing, This is the difference between a digital input module and an analog input module. In the input sampling phase, the PLC successively reads all input status and data by scanning and stores them in the corresponding cell in the I/O image area. After the end of the input sampling, the user program execution and output refresh phase. In both phases, even if the input state and data change, the state and data of the corresponding unit in the I/O map area will not change. Therefore, if the input is a pulse signal, the width of the pulse signal must be greater than one scan cycle to ensure that the input can be read in any case. The acquisition of the switching quantity is realized through the PLC input module, which is generally a DC 24V input. The PLC provides a common point, positive or negative, and then the common point is connected to the limit switch and other devices. When the limit is closed, the path is formed and the signal is introduced into the PLC input point. Specifically why the input point to power inside the state is on, is the function of PLC itself, you do not need to tube. Through the analog module, A/D (analog/digital) module, the external weight signal, temperature signal, pressure signal can be introduced, A/D module can accept the signal is 0-10V, 0-5V, -5-5V voltage signal and 0-20MA, 4-20MA current signal. If the signal obtained by the terminal acquisition module is not these standard signals, but also through the transmitter conversion, after the standard signal enters the A/D module, it will be converted by A/D into a number, the specific range is different PLC is not the same, these converted digital quantities, can be used by the program, conversion, processing, and finally get the required data displayed.
The servo driver, also known as the servo amplifier or amplifier, is a device that outputs the pulse signal or analog signal input from the controller to the motor after internal calculation and amplification. Drive control mode (1) PWM control (Shadik driver) PWM control technology: control the on-off and off-off of semiconductor switching devices, so that the output end can get a series of pulses with equal amplitude and unequal width, and use these pulses to replace sine waves or other required waveforms. By modulating the width of each pulse according to certain rules, the output voltage of the inverter circuit can be changed, and the output frequency can be changed. Advantages: 1) Low noise; 2) High efficiency at full load and can work in continuous conduction mode; 3) The ripple voltage is small; 4) The switching frequency is fixed, so the noise filter design is easier and the noise elimination is simpler; 5) The control method is easy to implement. Cons: 1) Due to the influence of the error amplifier, PWM loop gain and response speed are limited, PFM has a fast response speed; 2) PWM is less efficient at low load. 3) PFM control (Panasonic Drive)
The frequency of the modulated signal varies with the amplitude of the input signal, and its duty cycle is unchanged. Because the modulated signal is usually a square-wave signal with a change in frequency, PFM is also called square-wave FM.
Advantages:
1) The main advantage of PFM compared with PWM is efficiency;
2) PFM has the advantage of low static power consumption;
3) No finite flow function can not work in continuous conduction mode;
4) Compared with PWM, the output current of PFM is small;
For PFM and PWM with the same peripheral circuit, the peak efficiency PFM is comparable to PWM, but before the peak efficiency, the efficiency of PFM is much higher than that of PWM, which is the main advantage of PFM
Cons:
1) Filtering is difficult (harmonic spectrum is too wide);
2) The PFM frequency is lower than the PWM frequency, which will cause the output ripple larger than the PWM;
3) PFM control is more expensive than PWM control.
The company focuses on DCS, PLC, robot, large servo four systems
The main products are various modules/cards, controllers, touch screens, servo drivers
Company advantage: Supply imported original products, professional production of spare parts
One year warranty, fast delivery time, complete supply !！！
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