What RD78G32 is on the BOM
The Mitsubishi RD78G32 sits in the MELSEC iQ-R family as a PLC expansion module on the iQ-R backplane — a class of slice modules the series dedicates to motion and high-speed I/O rather than the base CPU slot. It files under PLCs and Accessories, sub-class PLC Expansion Modules, top-class PLCs & HMIs, which mirrors how the iQ-R racks treat any non-CPU base unit: a backplane-resident drop that inherits the CPU's project and power budget.
Lifecycle reading
No official successor order code is recorded against RD78G32 in the part record; if a future iQ-R platform migration retired this specific motion slice, the same record would carry the replacement MPN, and that field is presently empty.
Where the class is used
PLC Expansion Modules on the MELSEC iQ-R platform cover the high-speed, motion and dedicated-network slices that don't belong in the CPU's local I/O table — the kind of slots filled when a line needs multi-axis motion, a high-speed counter, or a specific fieldbus beyond the CPU's built-in ports.