The Mitsubishi Q12PRHCPU is a redundant PLC CPU module from the MELSEC-Q series, designed for high-availability control systems where a single CPU failure cannot interrupt the process. It supports 4096/8192 I/O points — the first figure is the local/remote I/O capacity, the second includes the total I/O points managed by the redundant pair. That headroom means you can run a substantial distributed I/O network without hitting the ceiling during normal operation or a failover event.
The module mounts in the MELSEC-Q base rack, occupying a single slot. Redundancy requires a second Q12PRHCPU and a tracking cable between the two CPUs — the pair runs in hot-standby, with the standby CPU synchronising the program and data via the dedicated bus. The 4096/8192 I/O count includes the points managed by both CPUs, so the I/O assignment table stays identical across the pair. No special backplane is needed beyond the standard Q-series rack.