This is a short-write up on the Melsec-Q series PLC CPU, depicting differences, specifications, discontinuation and replacements, and model identification.

Basic Model QCPU

Herewith the Basic Model Performance Specifications:

High Performance Model QCPU

Herewith the High Performance Model Performance Specifications:

Process Model QCPU

Herewith the Process Model Performance Specifications:

Redundant Model QCPU

Herewith the Redundant Model Performance Specifications:

Universal Model QCPU

Herewith the Universal Model Performance Specifications:


Herewith a summarized set CPU comparison;

CPU Model description Information:

CPU suffix descriptions:

Migration purposes;

Some information on the migration of Melsec-Q series CPUs

We see here that the Basic Models and High-Performance Modules are to be replaced by Universal Models.

table with the Program Capacity (Steps) vs Basic Operation Processing Speed (ns) vs. Communication Connection Options;

These are the Universal Melsec-Q CPU types: (QnU)

Comparison of Melsec-Q series comparison

As for the programming memory:

Melsec-Q Series Universal CPU Suffix

As for the CPU suffix descriptions:

Essential information via selection tool:

Some Melsec-Q CPU Comparison information via the Melsec-Q Selection Tool

Universal Model Specifications:

Melsec-Q Universal CPU specifications: