How to understand the PLC digital expansion module

Not necessarily. Take the Siemens S7-200's CPU 226 (24Di 16D0) as an example:

It can be scaled up to 248 DI DOs. Of course, if the 24Di 16D0 is already required by the process, the expansion module is not required.

The number of expansion modules that can be band is determined by the type of CPU, and the number of I O that can be band is also determined by the CPU. When it comes to practical use, it is the process that determines the selection.

Hope it helps.

No, the limit on the number of digital extensions is based on the maximum number of digital extensions of the selected PLC, and has nothing to do with the number of points in its base unit.

For example, the Mitsubishi FX1N's extension is up to 128 points.

The Mitsubishi FX2N's extension is up to 256 points.

The Mitsubishi Q001 has an extension of up to 1024 points.

There is no such statement, just that you don't have enough points in your machine, so use the points of the expansion module. There is no question of any more, but there are generally more extensions.

The number of points of the expansion module has little to do with that, it depends on how many inputs, it is best to use PLC, only digital input and more can choose the expansion module, the expansion module ** is not cheap, it is best to search from the professional ** what industrial control network transmission network.

Thank you for the invitation, let me give you my opinion:

Whether it is a digital input module or an analog input module of the PLC, their responsibility is to collect the signal into the PLC, and then, according to the instructions of the internal program, the PLC will release the command signal through the data output IO interface. In this way, through data input, PLC scanning, and data output, it constitutes a cycle of PLC working operation, now are you clear? If you need the relevant digital PLC input module, you can go to our ** for specific consultation, welcome to visit.

Summary. Siemens PLC expansion modules usually have input and output modules, digital modules and analog modules. Wherein, the digital module converts the input signal of the external digital device into a signal that can be recognized by the computer, so that the PLC can control other equipment through these inputs; The output module outputs the control signal of the computer to an external device.

Analog modules are used to process a variety of different types of analog signals, including temperature, pressure, velocity, and level. These signals can be thought of as measurements of certain physical quantities, and by converting these signals into digital signals using an analog module, the PLC can control the operation of other devices based on the results of the processing.

Excuse me, but please go into more detail?

Siemens PLC expansion modules usually have input and output modules, digital modules and analog modules. Wherein, the digital module converts the input signal of the external digital device into a signal that can be recognized by the computer, so that the PLC can control other equipment through these inputs; The output module outputs the control signal of the computer to an external device. The Analog Module is designed to handle a variety of different types of analog signals, including temperature, pressure, velocity, and level.

These signals can be considered as measurements of certain physical quantities, and the differential balance uses an analog module to convert these signals into digital signals, and the PLC can control the operation of other devices based on the results of the processing.

Summary. There is a difference. The digital module is to control each digital device through a programmable logic controller (PLC), which mainly refers to the control action of pressing the switch signal; The digital expansion module provides an expansion function in the PLC control system, increases the input and output channels of the system, and can realize more module combinations.

There is a difference. The digital module is to control each digital device through a programmable logic controller (PLC), which mainly refers to the control action of pressing the switch signal; The digital expansion lead expansion module provides an extended function in the PLC control system, increases the input and output channels of the system, and can realize more car combination modules.

1: PLC analog input module (analog input module), also known as AD module, converts the continuous analog signal generated by sensor detection into the digital amount that the PLC CPU can receive, generally more than 12 bits, and the more digital digits of the Zen manuscript Hui module, the higher the resolution. Two:

PLC analogue output module. The analog output module, also known as the D A module, converts the digital quantity sent by the CPU of the PLC to the analog output module into an analog collision amount (voltage or current) that can be received by an external device. The digital signal received by the analog output module is generally 12-bit binary number, and the more digital bits, the higher the resolution.

The digital module is to detect the state of the external switching input and answer.

Three: the digital input and output signal is the switching signal, 0 or 1, analog signal, there are 2 kinds, the reputation of the 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 PLC, PLC for data processing, which is the difference between the digital input module and the analog input module. During the input sampling phase, the PLC reads all input states and data sequentially in a scanning manner and stores them in the corresponding cells in the IO image.

After the input sampling is complete, it moves to 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 io image area will not change. Therefore, if the input is a pulsed signal, the width of the pulse signal must be greater than one scan period to ensure that the virtual input can be read in any case.

Digital input and output modules Analog input and output modules Are they 4 modules?

Answer: It can be yes or no, according to the type of PLC, some compact PLCs may concentrate these functions on a module, but they must have the corresponding functions of CPU, DI, DO, AI, AO, and the above modules can be selected according to the situation in the case of more points, and large and medium-sized PLCs have base plates or connectors that can be configured Separate CPUs (processor units), separate DI (digital inputs), separate DO (digital outputs), separate AI (analog inputs), separate AO (analog output) modules to form a complete PLC.

Analog and digital how PLCs are used in reality.

On the PLC side: the input refers to the signal input from the device to the PLC, and the output value is the signal output from the PLC to the device.

Digital quantities are generally 0 or 1, that is, high and low. The input terminal has a set of detection devices (light-emitting diodes and photocouplers) inside the PLC, and when the signal wiring point changes from low to high, the corresponding address point inside the PLC, such as: 0 becomes 1.

There will be a relay at the output or the transistor will be off when it is 0 and on when it is 1. When programming in the PLC, you can refer to the corresponding address for read and write operations.

Analog is a continuously changing quantity, such as temperature, flow rate, pressure, speed, etc., in a variety of signal types, and the analog module must be selected according to the type of these signals. For example, some instruments have a 4 20mA current signal, some have a 0 10V voltage signal, and there is a corresponding address inside the PLC for reading and writing.

For example, the PLC operates a frequency converter, the inverter starts and stops through the DO of the PLC, the operation status of the inverter such as: operation and fault are collected by the DI of the PLC, the speed control of the inverter is carried out through the AO, and the speed feedback of the inverter is carried out by AI.

These signals can be interlocked, linked or compared with the signals of other equipment in the PLC to achieve automatic control of a set of processes.

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Digital quantities transmit numbers, such as traffic is signals;

The analog quantity transmits the value of the voltage or current;

For example, the input is a current signal from 4 to 20 mA, which is called analog input, which converts it into a corresponding digital signal, and then calculates and processes the digital quantity;