Software redundancy principle is that when the process of the realization of the two CPU while the system is running up and running, but in normal operation only the main CPU to issue control commands, and the standby CPU to detect and record the main CPU status issued by the main CPU command, plc analog input When the main CPU modules can be sustained at the time plc analog output module of the failure of the state to take over the main CPU to issue actually execute the command. When specific fault occurs, the system can achieve standby switch, standby master station continues to run to succeed.
Hardware redundancy redundant system to ensure reliability of the system, such as all the major components are redundant configurations, including a redundant CPU, power supply module and the synchronization module for redundant CPU communication. Customers can also be configured accordingly redundant servers, redundant interface module, redundant communications media, etc. according to specific needs. Under normal circumstances high-speed counter modules hardware redundancy system can achieve the following functions.
A positioning error detection and error integration.
2 automatic event synchronization with smooth master-slave switch.
3 is similar to a standard CPU-line programming.
4 can be modified during operation of the system or components to be replaced.
5 Download the program when considering only a single CPU, the program can automatically copied to another CPU, and the automatic re-enter after the repair.