Characteristic Dimension

DCS CHASSSIS

PLC CHASSIS

Design Objective

A "control node" of the system construction

Build an "independent controller"

System Utilization

component of a large network and highly dependent on the system network (such as the control network, system bus)

Operating as an autonomous unit, it can independently complete tasks and then connect to the upper computer or other PLCs through the communication network.

Modularization and Expansion

Ultra-modular design: The rack itself may only provide power and backplane bus. All modules (CPU, I/O, communication) are installed as cards, supporting large-scale and distributed I/O, and can be expanded through field buses.

Centered on the CPU: The rack is closely built around the CPU module. I/O expansion can be achieved through local racks, expansion racks or dedicated networks. The expansion scale is usually smaller than that of DCS, but the speed is extremely fast.

Key Features

Redundancy is at the genetic level: it supports 1:1 controller redundancy, power redundancy, network redundancy, and most of these are with seamless switching. Hot swapping is standard, allowing for the replacement of faulty modules without power interruption.

Redundancy is usually an optional feature (supported by mid-to-high-end PLCs for controller redundancy), and its implementation method may not be as seamless as that of DCS. Hot swapping is common in mid-to-high-end models, but not all PLCs support it.