GE Fanuc PACSystems 热备份冗余CPU用户指南（中文）
Remaining CPU of hot spare
Redundant cpus are used in critical environments and continue to operate when a single component of the system fails. A redundant system uses two cpus, one of which is the active unit that controls the process, and the backup unit that synchronizes with the active unit and takes over program control if necessary. When the two units are in the running state, the backup unit receives the latest status and synchronization information from the active unit through a redundant communication module, and both units run their respective logic programs in sync. Each unit must have a redundant CPU(IC698CRE020) and one or two redundant communication modules (IC698RMX016). Several communication paths are provided by one or two pairs of RMX units.
When a fault in the active unit is detected, the control automatically switches to the standby unit. You can start controlling the conversion by activating the switch on the RMX module or by activating a switch service request through the application. When a user-defined control switch occurs, the CPU switches roles, the active unit becomes the backup unit, and the backup unit becomes the active unit.
The system maintains synchronization by controlling the exchange of data, including the state of the defined machines and all internal data necessary to keep the CPU in sync. Data is synchronized from the active unit to the backup unit twice per scan period. The CPU to CPU transmission is verified for data integrity.