On Tue, 6 Aug 2002, Tony Pan wrote:

> Hi,
>
> I am writing a safety-related software and need to detect if an input pin
> gets stuck at 1 (or 0). Could any one tell me how to do it in the software?


What's driving the input normally? SBO's in an RTU have to deal with this
issue. I've seen several designs involving resistors, bidirectional I/O
lines, diodes, capacitors, etc.

If you can route the input to two  I/O's and can momentarily make one of
them an output, then there's a good chance you can monitor a stuck line
(or detect a damaged input pin).

Scott

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