SDLC

SDLC (Software Development Life Cycle) is the structured process used to plan, design, build, test, release, and maintain software systems. In industrial and regulated environments, SDLC typically applies to MES, SCADA, PLC programming tools, data historians, quality systems, and other OT/IT software that support manufacturing operations.

The SDLC describes the end to end progression of software from concept through retirement. Common phases include:

• Requirements and analysis: Understanding user needs, regulatory constraints, interface requirements, and system boundaries.
• Design: Defining architectures, data models, interfaces, and security controls.
• Implementation: Writing and configuring code, scripts, logic, and integrations.
• Verification and validation: Testing functionality, performance, cybersecurity, and compliance behavior.
• Deployment and release management: Moving software into production environments in a controlled way.
• Operation and maintenance: Monitoring, patching, defect correction, and change control throughout the system’s life.
• Retirement: Decommissioning software, migrating data, and documenting transitions.

Use in industrial and regulated environments

In manufacturing and OT contexts, SDLC practices are often formalized to provide traceability, documentation, and evidence that software changes are controlled. This can include version control, documented requirements and test cases, change approval workflows, and impact assessments for safety, quality, and cybersecurity.

For industrial automation and control systems, secure SDLC approaches incorporate security activities into each phase, such as threat modeling, secure coding practices, vulnerability assessment, and security-focused testing. Standards like IEC 62443-4-1 define process requirements for a secure development lifecycle tailored to industrial systems.

Operational perspective

From an operational standpoint, SDLC typically shows up as:

• Formal procedures for how MES or SCADA changes are requested, designed, implemented, tested, and released.
• Required documentation (requirements, design descriptions, test records) that link software changes to production and quality impacts.
• Evidence trails used in audits to demonstrate control of software affecting product quality, data integrity, and safety-related functions.

Common confusion

• SDLC vs. secure SDLC: SDLC is the general lifecycle process for software. A secure SDLC explicitly integrates cybersecurity activities and controls into each phase.
• SDLC vs. PLC logic changes: Editing PLC or DCS logic can be part of an SDLC when treated as software development, but day to day parameter changes or setpoint adjustments in operations are usually handled under different procedures (for example, engineering change control or maintenance workflows).

Context: IEC 62443-4-1

Within the IEC 62443 framework, SDLC is addressed by IEC 62443-4-1 as a secure development lifecycle for industrial automation and control system products. IEC 62443-4-1 defines specific, auditable process requirements and documentation expectations that extend generic SDLC concepts with OT-focused security and long-lived system considerations.