Programmable Logic Controller (PLC) hardware measures:

The main modules are used large-scale or large scale integrated circuits, a large number of switching operations performed by non-contact electronic memory, plc IO module system design have improved the channel protection and signal conditioning circuit.
① shield - to power transformers, CPU, programmers and other major components, the use of electrical conductivity, magnetic shielding material good, to prevent outside interference.
② filter - the power supply system and an input line filter in various forms, such as intelligent plc or π-type filter network to eliminate or suppress high frequency interference, but also weakened the interaction between the various modules.
③ power adjustment and protection - the core components of the microprocessor needed a + 5V supply, the use of multi-stage filter and make adjustments with the integrated voltage regulator to adapt to fluctuations in the exchange and over-grid voltage, under influence of voltage.
④ isolation - between the microprocessor and I / O circuits, opto-isolated, effectively isolate the electrical connection between the I / O interface with the CPU contact, reducing failures and malfunctions; between the I / O port also isolated from each other.
⑤ with modular structure - This structure helps in case of failure to repair short. Once identified a faulty module can easily be replaced quickly, allowing the system to resume normal work; also helps to accelerate find the cause of the fault.