License & Deployment Mix: 14 tools – 5 OSS, 0 SaaS. (OSS and SaaS counts can overlap when an open-source tool also offers a vendor-hosted edition.)

What Is a Soft PLC?

A Soft PLC (Software PLC) is a software-based programmable logic controller that runs on standard PC or Linux hardware instead of dedicated, purpose-built PLC hardware. Soft PLCs execute the same control logic – ladder diagrams, function blocks, structured text – that traditionally required proprietary industrial controllers, but on commodity x86 or ARM processors with standard operating systems.

The term Software Process Control encompasses the broader category of software systems that manage and automate industrial processes, including soft PLCs, soft motion controllers, and PC-based automation platforms. These systems blur the line between traditional IT infrastructure and operational technology (OT).

Soft PLCs are defined by the IEC 61131-3 standard, which specifies five programming languages for industrial automation:

• Ladder Diagram (LD) – graphical language resembling electrical relay logic; the most widely used PLC language, especially by electricians and maintenance technicians
• Function Block Diagram (FBD) – graphical language using interconnected function blocks; common in process control and continuous processes
• Structured Text (ST) – high-level textual language similar to Pascal; preferred by software engineers for complex algorithms and data processing
• Instruction List (IL) – low-level textual language similar to assembly; deprecated in IEC 61131-3 Edition 3 but still supported by many platforms
• Sequential Function Chart (SFC) – graphical language for defining sequential and parallel process steps; used for batch control and state machine logic

A newer standard, IEC 61499, extends IEC 61131-3 with event-driven, distributed automation concepts using function blocks that can execute across multiple networked controllers.

The information on these pages was researched by a combination of human review and large language models. To suggest an addition or correction, please contact us. Prepared by Rhodium Systems Inc., author of the ResorsIT platform — a unified IT operations management platform for IT teams and MSPs that integrates a curated suite of open-source, commercial, and SaaS applications into a single system with shared identity, single sign-on, access control, and a common audit trail. Use this catalogue only as a starting point for your own research, and review any tool carefully against your own requirements before relying on it. Catalogue data version 2026.197.

Comparison

Deployment Model

IEC 61131-3 Language Support

Best IEC 61131-3 coverage: CODESYS, TwinCAT 3, B&R Automation Studio, Straton (all five languages)

IEC 61499 support: 4diac FORTE (native), ISaGRAF (both standards)

Fieldbus / Protocol Support

Best protocol breadth: CODESYS, TwinCAT 3, B&R Automation Studio, ISaGRAF, Straton (all major fieldbuses)

Best OSS protocol support: OpenPLC (Modbus only), Beremiz (Modbus + CANopen)

Real-Time Capabilities

Best real-time performance: TwinCAT 3, B&R Automation Studio (sub-100-microsecond cycle times for motion control)

OSS real-time: LinuxCNC (hard RT with PREEMPT_RT or RTAI kernel)

IDE / Programming Environment

Best IDE: TwinCAT 3 (Visual Studio integration), CODESYS (industry standard IDE), B&R Automation Studio

Web-based: OpenPLC (full web IDE), PLCnext (web-based engineering + desktop)

SSO / Authentik Integration

Best Authentik integration: CODESYS (Automation Server supports OIDC), PLCnext (web portal supports OIDC)

Most soft PLC platforms are desktop IDEs and embedded runtimes with no web-based SSO. OIDC is relevant only for web management portals and cloud-based engineering tools.

API Capabilities

Best API: CODESYS (REST + webhooks + Python scripting + CLI), PLCnext (REST + webhooks + CLI + app store)

Monitoring Integration

Best monitoring integration: PLCnext (health endpoint + syslog + SNMP + Prometheus metrics), CODESYS (health + logs + SNMP + OPC UA metrics), B&R Automation (health + logs + SNMP + OPC UA)

For all platforms, Telegraf monitors the host system (CPU, memory, disk, network). PLC-specific metrics typically require OPC UA or proprietary protocol integration.

Pricing

Open Source / Free

Commercial – Free Tier Available

Commercial – Paid Only

Suitability Summary

Best for Learning / Prototyping

• OpenPLC – free, web-based IDE, runs on Raspberry Pi and Arduino; ideal for education and small prototyping projects
• Beremiz – free IEC 61131-3 IDE with all five languages; good for learning IEC standards

Best for Production (OSS)

• LinuxCNC – mature GPL CNC controller; hard real-time; proven in production CNC and motion control applications
• 4diac FORTE – IEC 61499 distributed automation; suitable for distributed control systems

Best for Production (Commercial)

• CODESYS – industry-dominant IEC 61131-3 platform; embedded by 400+ OEMs; broadest fieldbus support; strong ecosystem
• TwinCAT 3 – best-in-class real-time performance; native EtherCAT; Visual Studio integration; dominant in high-performance motion control
• B&R Automation Studio – full automation suite (PLC + motion + HMI + safety); ABB ecosystem; strong in machine building

Best for OEM Embedding

• CODESYS – dominant OEM runtime; licensed to 400+ automation vendors; runs on ARM and x86; certified for SIL 2/3
• Straton – lightweight OEM runtime by COPA-DATA; small footprint; fast boot; suitable for embedded controllers
• ISaGRAF – Rockwell-owned; IEC 61131-3

• IEC 61499; embedded in diverse targets

Best for IT/OT Convergence

• PLCnext – Linux-based, open ecosystem, Prometheus metrics, Docker/OCI app support, web engineering; closest to IT-native automation platform
• CODESYS – Automation Server for fleet management, OIDC support, REST API, broad IT integration options

Tools

14 tools.

4diac FORTE

4diac FORTE is an open-source distributed automation runtime implementing the IEC 61499 standard.

License: EPL-2.0 (OSS) · Kind: web · Deploy: native · SSO: none

Website · Source

B&R Automation Studio

B&R Automation Studio is a comprehensive automation engineering environment and soft PLC runtime from B&R Industrial Automation, a subsidiary of ABB.

License: Proprietary (proprietary) · Kind: web · Deploy: native · SSO: none

Website

Bachmann M-PLC

Bachmann Electronic is an Austrian automation company specializing in control systems for energy, marine, and industrial applications.

License: Proprietary (proprietary) · Kind: web · Deploy: native · SSO: none

Website

Beremiz

Beremiz is an open-source integrated development environment and soft PLC runtime for IEC 61131-3 programming.

License: LGPL-3.0-only (OSS) · Kind: web · Deploy: native · SSO: none

Website · Source

CODESYS

CODESYS (Controller Development System) by 3S-Smart Software Solutions is the dominant IEC 61131-3 soft PLC platform worldwide.

License: Proprietary (proprietary) · Kind: web · Deploy: native · SSO: none

Website

ISaGRAF

ISaGRAF is an IEC 61131-3 and IEC 61499 soft PLC development environment and runtime, now owned by Rockwell Automation.

License: Proprietary (proprietary) · Kind: web · Deploy: docker · SSO: none

Website

LinuxCNC

LinuxCNC is a mature, open-source CNC machine controller and soft PLC that has been in development since the early 1990s (originally NIST EMC, then Enhanced Machine Controller).

License: GPL-2.0-only (OSS) · Kind: web · Deploy: native · SSO: none

Website · Source

OpenPLC

OpenPLC is an open-source programmable logic controller designed for industrial automation, education, and research.

License: GPL-3.0-only (OSS) · Kind: web · Deploy: native · SSO: none

Website · Source

PLCnext

PLCnext Technology by Phoenix Contact is an open, Linux-based automation platform that combines IEC 61131-3 PLC programming with high-level language programming (C++, C#/.NET, MATLAB/Simulink) on a single runtime.

License: Proprietary (proprietary) · Kind: web · Deploy: native · SSO: none

Website

Proview

Proview is an open-source process control system developed originally by SSAB (Swedish steel manufacturer) for in-house use, later released under the GPL.

License: GPL-2.0-only (OSS) · Kind: web · Deploy: native · SSO: none

Website · Source

Siemens PLCSIM Advanced

Siemens PLCSIM Advanced is a software-based PLC simulator that emulates Siemens S7-1500 and ET 200SP controllers on a standard Windows PC.

License: Proprietary (proprietary) · Kind: web · Deploy: native · SSO: none

Website

SoftPLC

SoftPLC is a commercial soft PLC runtime from SoftPLC Corporation that runs on standard Linux PCs, providing IEC 61131-3 compliant PLC execution without dedicated PLC hardware.

License: Proprietary (proprietary) · Kind: web · Deploy: native · SSO: none

Website

Straton

Straton is a lightweight, high-performance soft PLC runtime developed by COPA-DATA, primarily designed for OEM embedding in third-party automation hardware.

License: Proprietary (proprietary) · Kind: web · Deploy: docker · SSO: none

Website

TwinCAT 3

TwinCAT 3 (The Windows Control and Automation Technology) by Beckhoff is a high-performance soft PLC and motion control platform that runs on Windows with a kernel-level real-time extension.

License: Proprietary (proprietary) · Kind: web · Deploy: native · SSO: none

Website