Dear Colleagues,

Firstly, a happy festive season for you over the next few weeks. Seeing the economic engines of the world economies gradually ramping up, I think at least from an engineering perspective, 2014 looks promising.

Have you ever noticed that often most of your challenges in engineering are found at ‘the interface’? By interface, I mean where two elements meet each other – the boundary between two different systems.

Often you find examples of poor design and failures at the interface. Whether it be two different electronic circuits connecting together or two engineering professionals working together – an electronic engineer and mechanical engineer. A plumber working with an electrician or a substation connecting to the power electrical transmission system. Or indeed a C++ program interfacing to an API.

So I am not thinking only of electronic and electrical hardware but also people/processes and systems.

Give me Examples of Interface Problems

Examples of interfaces which create problems range from:

  • Connectors and cables which make intermittent connections between different circuits
  • Relay contacts (pitted or burned contacts) which then fail to connect (or do so intermittently)
  • Two different circuits with different grounds connect together (producing ground loops)
  • Data communication and wireless links between different systems which provide intermittent communications
  • Programmable Logic Controller software and hardware. Incompatible demands made by the software on the hardware
  • SCADA interface to the human operator – making excessive demands on the operator with too many alarms and information she can’t process or act upon.

Non-Hardware Interfaces Are Also there to Taunt you
People interfaces can be the most challenging. In a multidisciplinary design team, especial care has to be taken that communication between different types of engineering professionals is done well so nothing is forgotten in the design process. This is worsened by virtual multi disciplinary teams working on an international basis with the added complications of different cultures/time zones and telecommunications links.

Suggestions on Tackling the Interface
When aiming for an outstanding design or troubleshooting a problem, a suggested plan of attack is as follows:

  • Identify the interfaces
  • List from highest to lowest risk ones
  • Consider the problems that could occur at these interfaces
  • Put extra care into minimising interface issues with your design (eliminate them or make one person responsible for managing and defining interface problems and then in eliminating them)

Thanks to Lou Frenzel of Electronic Design magazine for a thought provoking article entitled: Trouble at the Interface which I have then extended to the impact on general engineering issues.

Jef Raskin hits the nail on the head with his comment: An interface is humane if it is responsive to human needs and considerate of human frailties.

Yours in engineering learning,

Steve Mackay