core Estimated learning time: 10 h

EC-14.5 Integration, and Why Systems Fail at the Joins

You can plan an integration so that faults are found one at a time, recognise the interface mismatches that cause most integration failures, analyse a failure to its cause rather than to its symptom, and hand a system over with the information the next person needs.

Before:EC-13. Laboratory Practice, in SequenceUnlocks:EC-15. Capstone, in Two Stages EC-17. Industry and Research Experience

Every part working alone and nothing working together is the most common state of a student project two weeks before the deadline. The cause is almost always an interface that was never written down, which is why this topic sits after the architecture one and refers back to it. Integrating incrementally is the single practice that prevents it.

Work through these

Integrating one piece at a time
Connecting everything at once produces a system that fails for an unknown number of reasons at once. Adding one subsystem, testing, and adding the next means each fault is found while it is still alone.
NPTEL: Project Management (IIT Kanpur) · Course
The interface mismatches that cause most failures
Units, ranges, timing, byte order, voltage levels and what each side does when the other stops answering. These six account for a large majority of integration problems in student and professional work alike.
NPTEL: Product Design and Innovation (IIT Guwahati) · Course
Building a test harness for a part that has no partner yet
A simple stand-in that produces the expected inputs lets a subsystem be tested before the rest exists. It also becomes the tool that isolates that subsystem during later fault finding.
NPTEL: Product Design and Innovation (IIT Guwahati) · Course
Failure analysis to a cause, not to a symptom
It stopped working is a symptom. Asking why repeatedly until you reach something that can be fixed, and checking whether the same cause could produce other faults, is the analysis.
NPTEL: Research Methodology (IIT Madras) · Course
Emergent behaviour, and the failures nobody designed
A supply dip when two subsystems draw current together, or interference from one into another, belongs to no single part. These appear only at integration, which is a reason to integrate early rather than late.
NPTEL: Measurement and Instrumentation (IIT Guwahati) · Course
Handing over, and what the next person needs
The design files, the test results, the known faults and the things you would do differently. A handover that omits the known faults transfers the work and keeps the knowledge.
NPTEL: Technical Communication for Engineers (IIT Roorkee) · Course

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