The Mitsubishi A2ACPUR21 is a high-performance redundant CPU module designed for the MELSEC-A series of programmable logic controllers (PLCs). This module is a crucial component for building fault-tolerant, high-availability control systems. It operates in a dual-CPU configuration, ensuring seamless and automatic switchover to a standby CPU in the event of a failure in the primary unit. This redundancy guarantees continuous operation and minimizes downtime, making it ideal for critical applications in process control, manufacturing, and infrastructure where system reliability is paramount.