MELSEC-Q I/O expansion — what the Q312DB does in a panel
The Q312DB is an I/O extension module for the Mitsubishi MELSEC-Q series PLC, designed to add input/output capacity to a base system. It accepts up to 12 input or output units, giving you the slot count to scale a Q-series rack without swapping the CPU. It draws 0.24 A from the 5 V DC backplane supply — factor that into your power budget when loading the rack, especially if the base power supply is already serving a CPU and a few high-current specialty modules.
Mounting and panel fit
The module mounts with M4 screws through 4.5 mm holes, or via an optional DIN rail adapter (Q6DIN1, sold separately). The 439 mm width and 98 mm height mean it spans most of a standard 19-inch subpanel width — plan your backplate layout so the screw holes align with the mounting pattern.
Lifecycle and sourcing reality
Typical lead time runs 1 to 10 working days through distribution, but this shifts with demand and backlog.