I had a look round to try to find out if it had failed green or black - unfortunately as all the news reports seem to be copies it doesn't seem possible to tell. If it did fail to black (as is implied in some places) then I guess they could be SIL4?
As you say, it would be very interesting to know.
I have to say, with the best will in the world it is hard to defend yourself against a determined slug. Of course I agree conformal coating is a good start, but I would never quote it as a fail-safe preventative - apart from anything else it can be stripped by rat urine! (It's a lovely job analysing SIL4 failure modes
) But what should be possible is to ensure that the signal fails black.
Andy Millar CEng MIET CMgr MCMIhttp://www.linkedin.com/in/millarandy
"The aim of argument, or of discussion, should not be victory, but progress." Joseph Joubert