The digital input module is the processing module that gives the external control signal or field detection signal to the PLC CPU, and the external signal is generally the button, the proximity switch, the travel switch, etc.
The digital output module is the PLC according to the input module input signal and internal logic programming logic processing, after processing the result, the switching output will be output by the output module high and low level signal, drive the external intermediate relay, contactor, indicator light, solenoid valve and other components, and then make the external equipment to carry out the corresponding action.
In practical applications, if the load requires too much power, the digital output module cannot meet the demand. At this point, there are two ways to design:
Using an intermediate relay, the digital output drives the coil of the intermediate relay.
Multiple digital output points drive the load in parallel. At this time, pay attention to the consistency of the action of multiple output points.
A PLC (Programmable Logic Controller) is a digital controller used to control machinery or production processes. Here are the advantages and disadvantages of PLCS:
Advantages:
High reliability: PLC uses advanced hardware and software design, T8402 has a strong anti-interference ability, can work stably and reliably in industrial environments.
Easy to program and maintain: PLCS typically use a simple programming language and intuitive interface, and the T8402 makes it easy for engineers to write programs and debug them. In addition, the PLC also has a self-diagnostic function, which can quickly identify faults and repair them.
Good flexibility: PLC can expand its function by adding or removing modules to meet different control needs. In addition, the PLC can also support a variety of different communication protocols to communicate with various devices.
High speed: PLC adopts high speed CPU and optimized program design, which can realize fast control and data processing and fast response speed.
Cons:
Higher price: Compared with traditional electrical control devices, the price of PLC is higher.
High technical threshold: PLC programming needs to master professional programming technology and knowledge, and there are certain requirements for the comprehensive ability of engineers.
Easy to be attacked: Because PLC is connected to the network, there is a certain network security risk, easy to be hacked.
