安全系统软件设计SWDesign.pptVIP

Part 06Software Design Heidi Fuglum Certified Functional safety engineer 06 Software design Software design In the module Software lifecycle Hardware, software relationship A typical software problem Safe software Three types of software Three types of development languages Software tools Safety Lifecycle, where are we Safety Lifecycle, where are we Hardware Software Relationship Software example A client order Software example In the specification Reqirement 1.2.83 Calculate the pressure with the following formula The programmer Programs according to 1.2 83 Tests requirement 1.2.83 Program is done according to the specification Software example What can go wrong? Is the specification correct? This project not… Was the program correct Yes, the test showed that the program was correct according to the spec Was the test correct? Was the test verified? Who verified the test? Did we actually do the test? Who verified the result? Software example Software testing is Not about every single line of code About having the right process and methods to test What we need to achieve is safe software Software is safe if The safety system can execute the safety function even under faulty conditions Not only software faults but also hardware faults Fault Free Software How do we do that ? Consider software engineering practices and quality assurance Select appropriate measures to avoid failures IEE 61508, part 3, table And B Periodically review the effectiveness of the methods to avoid faults during software development Standard, look at the ABB standard portal or at the LCC database Standards for ABB internal use only Three Types of Development Software IEC 61508 deals with Full variability languages (FVL) C, C++, Assembler IEC61511 deals with Limited variability languages (LVL) Function blocks, ladder logic Fixed programming languages (FPL) A sensor with only an up and down button to set a limit IEC61511 Do not differentiate between SIL 1, 2 or 3 software, all r