What is PLC software (or Soft PLC)?
A new generation of software automation
Definition
A Software PLC, or software-based programmable logic controller, is a solution that performs the same functions as a physical PLC, but runs on a software platform. It can run on various operating systems, such as Linux, Windows, VxWorks, FreeRTOS or QNX, and can be installed on industrial PCs, embedded electronic cards or existing equipment (RTUs, IEDs, gateways, etc.).
The strengths of PLC software
Time to market
It is as easy to transform a card into a PLC (2 days of integration) as it is to add a communication protocol. Card and application development can therefore be carried out in parallel.
Flexibility
Thanks to the source code, it is possible to change the CPU and/or OS while retaining applications written in IEC61131, thus enabling multiple markets to be addressed.
Openness
PLC software is a simple application building block that can work with other applications (motion, HMI, gateway, business application, etc.).
Compliance with standards
Soft PLC allows the use of the five languages of the IEC61131 standard, and certification is simplified thanks to compliance with protocol standards (IEC61850, IEC101/104, DNP3, etc.).
Financial
A single investment is all it takes to create an unlimited number of applications and control the price of your products throughout their life cycle. What's more, you can invest exclusively in the protocols you need.
Security
The soft PLC provider supplies sources and security updates to enable you to comply with the latest market standards, allowing you to focus exclusively on your business.
Performance
The same logic engine can run on low-performance hardware (e.g. 128 KB RAM) or on powerful servers managing up to 500,000 variables.
Product differentiation
In addition to adding PLC functionality to your products, customisation will be optimal with the addition of features such as HMI, motion control, business applications, gateways, etc.
IEC61131-3
For many years, the control systems market has seen the proliferation of a variety of programming languages and development environments, which differ from one manufacturer to another.
IEC 61131 standardises programmable controller technology and covers equipment requirements, programming languages, usage guidelines, communications and functional safety.
The third part of IEC 61131 (IEC 61131-3) deals with the five programming languages used in programmable logic controllers.
IEC 61131-3 defines a series of functions and data types that must be supported by all compliant programmable controllers. Functions are the basic elements of all programmes and include arithmetic operations (addition, subtraction, etc.), Boolean logic (AND, OR, NOT, etc.) and programming structures such as loops, comparisons and decisions.
One of the results of the adoption of the IEC61131 standard was the recognition that the software and hardware elements of programmable logic controllers could be considered separately, giving rise to the concept of Software PLC, or virtual PLC.
Safety and security concerns - soft PLC
Safety and security will always be major concerns for any automation system component. Misconceptions about the safety and security of SoftPLCs stem mainly from early solutions running on non-deterministic operating systems. It is possible to develop a resilient, safe and secure solution using SoftPLC technology, which is what almost all manufacturers do.
One of the advantages of SoftPLC solutions is that hardware and operating system choices can be made independently, based on safety and security requirements.
In addition, some SoftPLC solutions have even developed variants that can be integrated by OEMs into systems intended for IEC61508 (functional safety) certification. To do this, they reduce the overall functionality, remove features that could create safety risks, and provide approved methods for developing the runtime.
Summary of PLC software
Much has changed in the 20 years since the IEC61131-3 standard was created, and most popular 'conventional' PLCs now operate using SoftwarePLC technology. As with any choice of solution, requirements must determine the answer, but SoftPLC-based solutions should be considered in any discussion.
| Classic PLC | Soft PLC | |
|---|---|---|
| Platform | Dedicated hardware | PC/RTU/Embedded equipment |
| Operating system | Proprietary | Windows, Linux, RTOS... |
| Maintenance | Vendor-dependent | Independent, flexible |
| Integration | Closed | Open, interoperable |
straton software: a complete Soft PLC solution
STRATON AUTOMATION is part of the international COPA-DATA group
With over 23 years of expertise, we have the capacity to support you in all your automation projects.
straton is currently used in numerous embedded industrial solutions and by equipment manufacturers around the world.
straton software is designed to be embedded directly into your equipment and to act as a true software controller. It meets the requirements of several industrial sectors thanks to:
Soft PLC use cases
Embedded automation
in equipment (IED, RTU, gateway, etc.)
Distributed systems
(smart grids, Industry 4.0, IoT applications)
Virtualisation
of test equipment for development benches
Real-time solutions
for critical systems
Learn more: Webinar "What is a Soft PLC?"
Discover in detail the advantages, use cases and a live demonstration of straton as a Soft PLC.
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