PLC hardware anti-interference measures should be taken

( 1) Block: the power transformer, the main part such as CPU, programmer, conductive, permeability good material for shielding, in case of interference. ( 2) Filtering: the power supply system and the input line, adopt various kinds of filtering to eliminate or suppress the high frequency interference, also weakened the interaction between the various modules. ( 3) : power adjustment and protection needed for the core components of the CPU + 5 v power supply, using multilevel filter, and the integrated voltage regulator to adjust, to adapt to the ac grid fluctuation and the influence of the overvoltage, undervoltage. ( 4) Isolation: between CPU and I/o circuit, using photoelectric isolation measures, effectively isolate the electrical contact between the I/o, reduce fault misoperation. ( 5) Adopts modular structure: this structure will help in fault cases, short-term fix. Because once investigated a module failure, can quickly change, make the system back to normal work, can also help to search the cause of the problem.