1 June 2005

ISA Certified Automation Professional (CAP) Program

This question is from the CAP study guide, Performance Domain III, System Design.

Definition: Design, specify, and procure the hardware/software used in the system.

CAP question

Which of the following standards applies to the development of embedded software for a SIL 3 certified safety system?


B. EC 61511

C. IEC 61508

D. 21 CFR Part 11

CAP answer

The correct answer is C, IEC 61508.

According to IEC 61511-1, embedded software, which is part of the safety device/controller, should follow software guidelines in IEC 61508-3.

IEC 61511 and ANSI/ISA-84 are system standards and not product standards. 21 CFR Part 11 is not relevant as it deals with electronic signature.

The standards bodies in acronyms are the International Electrotechnical Commission (IEC), American National Standards Institute (ANSI), ISA-The Instrumentation, Systems, and Automation Society (ISA), and the Code of Federal Regulations (CFR), which refers to the U.S. federal government. Reference: IEC 61511, IEC, 2003.

Nicholas Sheble (nsheble@isa.org) edits the Certification department. For information about the CAP program, go to www.isa.org/CAP.