In some applications that require high reliability of the system, DCS design needs to consider hot backup, which is system redundancy,this refers to some key modules or networks in the system that have one or more backups,When something goes wrong with the current job,the system can be automatically switched to backup by special software or hardware to ensure the uninterrupted work of the sysytem.Usually the designed redundant modes including CPU redundancy,network redundancy and power supply redundancy.In some extreme cases,some systems will consider system-wide redundancy which means I     /O redundancy is included. System redundancy is also a reflection of high reliability of DCS;the UW500 (UWinPAS500)/UW600 (UWinPAS600) distributed control system is full hardware redundancy fault tolerance,no single point fault failure, single reload, multiple hardware redundancy voting, switching time 5-50ms;the redundancy mechanism is as following:

Power module hot backup redundancy,controll module,IO module,controll network,system network all supports hardware duplication,hardware built-in voting algorithm to realize zero switching time;

I/O module internally installed the input voting algorithm,output voting algorithm and input output self-check and failure reporting mechanism of both the switching value and analog quantity.

Input module,control module,output module,can adopt various redundant syntagm of single or dual configuration ,flexible configuration of redundant solutions;

High reliable IO module,channel to channel isolated,online diagnose, channel to channel online replacement，fault identification to the point level,further reduce average repair time MTTR;

The high reliability of UW500（UWinPAS500）/UW600（UWinPAS600）distributed control system is mainly reflected in the following aspects: 

System full hardware redundancy fault tolerance；

The high reliability I/O Modules are channel tochannel isolated, channel tochannelinter-isolated, channel tochannel power supply, channel tochannel Removal/Insertion Under Power, meeting requirements of high reliability & security fields like nuclear power and emergency shutdown;

Both module and modules support microprocessor，distributed collaboration, self-diagnosis self-recovery, fault isolation, online replacement;

Supports Voltage/Current/Thermal resistance/Thermocouple full range accuracy universal analog input,self - diagnosis and self-correction, free from adjustment or maintenance;  

Electromagnetic compatibility design,low-power design, it does not need to be forced to dissipate heat and adapt to the harsh industrial environment;

Multi-user hierarchical security mechanism;data power-off protection,redundancy check,quick recovery ,secure information.

Distributed Control System is a multilevel computer system composed of process control level and process monitoring level by the link of communication network,conprehension of computer,communication,CRT ,Control and other 4C technologies.