The Mitsubishi Q312BE is a 12-slot base unit for the MELSEC-Q series PLC rack. It provides the mechanical backplane and power distribution for up to 12 modules — CPU, I/O, special-function, or network — in a single rack. The 1 W power draw is the base unit's own consumption; the module slots supply the system power from the connected power supply module.
The 12-slot layout leaves one slot reserved for the power supply module (per Mitsubishi's rack configuration rules). Slot numbering starts from the left; the CPU occupies slot 0, and the remaining 11 slots accept any Q-series module. The base unit carries no active electronics beyond the backplane bus — all slot current is drawn from the power supply module, not the base.
