What are the software safety standards to follow when programming industrial automation systems?

1 What are software safety standards?

Software safety standards are a set of guidelines, requirements, and best practices that aim to ensure software systems perform their intended functions without causing harm or damage. Depending on the domain, application, and complexity of the software system, standards can be general or specific. For industrial automation systems, software safety standards typically cover topics such as software lifecycle management, software quality assurance, software risk assessment, and software safety engineering. Specifically, these standards address how to plan, design, implement, test, deploy, maintain software systems in a systematic and traceable way; how to verify and validate software systems against functional and non-functional specifications; how to identify, analyze, evaluate, and mitigate potential hazards and failures; and how to apply engineering principles and methods to design and implement software systems that prevent or reduce the occurrence and severity of hazardous events.

2 Why are software safety standards important?

Software safety standards are important for several reasons. First, they help to protect the health and well-being of workers, customers, and the public who may be exposed to industrial automation systems. Software errors or malfunctions can cause serious injuries or fatalities, as well as property damage and environmental pollution. For example, in 1986, a software bug in a radiation therapy machine led to the overdosing of six patients, resulting in three deaths. Second, they help to ensure the compliance and accountability of software developers and users with legal and ethical obligations. Software systems that do not meet safety standards can result in lawsuits, fines, penalties, and reputational damage. For example, in 2010, Toyota recalled millions of vehicles due to a software defect that caused unintended acceleration. Third, they help to improve the performance and efficiency of industrial automation systems. Software systems that are safe, reliable, and robust can reduce downtime, maintenance costs, and waste, as well as increase productivity, quality, and customer satisfaction.

3 How to follow software safety standards?

Software safety standards are used to ensure the safety of industrial automation systems, and vary depending on industry, sector, and region. Popular standards include IEC 61508, which covers the entire lifecycle of safety-related systems and defines four levels of safety integrity (SIL 1 to SIL 4). IEC 61131-3 is specific to programmable logic controllers (PLCs), and outlines five programming languages and common elements like variables, data types, functions, and programs. IEC 62061 is tailored to machinery, defining three levels of safety integrity (SIL 1 to SIL 3) and providing guidance on how to allocate SIL levels and use software tools. To follow software safety standards, you must adhere to a structured process that covers all phases of the software lifecycle, use appropriate software tools and techniques, and keep track of requirements, specifications, and evidence.

4 What are the benefits of following software safety standards?

Adhering to software safety standards can bring many advantages to your industrial automation projects, such as reducing the risk of accidents and injuries, improving the reliability and performance of systems, boosting the quality and customer satisfaction of products and services, increasing competitiveness in the market, as well as fulfilling legal and ethical obligations.

5 What are the challenges of following software safety standards?

Following software safety standards can also pose some challenges to your industrial automation projects. These include increased complexity, cost, and time of software development and maintenance, as well as the need for specialized skills, knowledge, and experience in software safety engineering and management. Furthermore, adapting to different and changing software safety standards across industries, sectors, and regions can be a challenge. Finally, integrating and coordinating the software safety standards with other aspects of the industrial automation system (e.g., hardware, operators, environment) is essential but not always easy.

6 Here’s what else to consider

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