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PLCs and control systems

Browse programmable logic controllers, CPUs, distributed I/O, communication modules and control-system accessories across leading industrial automation platforms.

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Choose the controller role first

Start with the system architecture and required function, then confirm the manufacturer platform and complete order number.

Controller type

Compact PLCs

Controllers with integrated processing, communications and onboard I/O for compact machines.

Controller type

Modular PLCs and PACs

Scalable controller platforms for larger I/O counts, networks and coordinated automation tasks.

Safety control

Safety PLCs

Fail-safe controllers and safety I/O intended for engineered safety functions.

Core hardware

PLC CPUs

Central processing units for expanding, repairing or standardizing installed control systems.

Signal interface

I/O modules

Digital, analog and special-function modules for local and distributed signals.

Connectivity

Communication modules

Interfaces and processors for industrial Ethernet, fieldbus and controller networking.

Controller platforms and product families

Move into a manufacturer platform when the installed control architecture or engineering environment is already known.

Siemens

SIPLUS S7-1200

Siemens compact-controller variants for demanding environmental conditions.

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How to specify a PLC requirement

A family name is not enough to identify a compatible controller. Capture the electrical, software and lifecycle constraints before selecting a replacement or expansion module.

For an installed system, use the complete manufacturer order number and hardware revision. Similar family names do not guarantee interchangeability.

  1. 01

    Define the control architecture

    Establish whether the application needs a compact controller, modular rack, distributed controller or safety architecture.

    • Controller topology
    • Required redundancy
    • Safety functions
  2. 02

    Count and classify the I/O

    Record signal types, channel counts, isolation and any high-speed or special-function requirements.

    • Digital and analog I/O
    • High-speed signals
    • Local or remote I/O
  3. 03

    Confirm networks and interfaces

    Match the installed fieldbus, industrial Ethernet and device-level communication requirements.

    • Industrial Ethernet
    • Fieldbus protocol
    • Serial or specialty links
  4. 04

    Verify software and firmware

    Check the engineering tool, project version, CPU firmware and module support before changing hardware.

    • Engineering software
    • Firmware version
    • Existing project compatibility
  5. 05

    Review installation conditions

    Confirm power, cabinet space, temperature, approvals and environmental protection requirements.

    • Supply voltage
    • Operating environment
    • Certifications

Place the PLC inside the complete automation system

Controller selection depends on every layer that exchanges signals, diagnostics or motion commands with the PLC.

01

Sensors and field devices

02

Local and distributed I/O

03

PLC / PAC

04

HMI and supervisory systems

05

Drives, motion and actuators

Planning replacements for legacy controllers

When an original PLC, CPU or module is obsolete, preserve the installed system context before comparing a successor or sourcing the same order number.

  • 01

    Photograph the complete product label and connected modules.

  • 02

    Record the CPU firmware, memory device and engineering-software version.

  • 03

    Back up the application before removing powered equipment.

  • 04

    Check whether the replacement changes wiring, network addressing or I/O behavior.

PLCs and control systems questions

Practical checks for identifying, selecting and replacing controller hardware.

What is the difference between a PLC and a PAC?

The terms overlap. PLC commonly describes an industrial controller used for deterministic machine and process logic, while PAC is often used for higher-capacity, multi-domain controller platforms. The manufacturer family, supported I/O, software and communications matter more than the label alone.

Can a newer PLC CPU directly replace an older one?

Not automatically. Check rack or base compatibility, power requirements, I/O support, communications, firmware, engineering software and the existing application before treating a newer CPU as a replacement.

Why is the complete PLC part number required?

Suffixes and revisions can identify supply voltage, memory, communication ports, environmental variants, safety capability and regional approvals. A shortened model name can therefore identify the wrong hardware.

Can legacy and discontinued PLC components still be sourced?

Availability depends on the exact order number and required condition. Options may include new original stock, new surplus, used, refurbished or repaired equipment, subject to inspection and commercial confirmation.

Need help sourcing plcs and control systems?

Send the manufacturer, complete order number, required condition, quantity and delivery destination for a tailored quotation.

Request a quote