From 470f9e52d9dda39df0d8ddaac79df38ee7d0be83 Mon Sep 17 00:00:00 2001 From: robin Date: Sat, 7 Apr 2012 18:01:04 +0100 Subject: [PATCH] .. --- papers/software_fmea/software_fmea.tex | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/papers/software_fmea/software_fmea.tex b/papers/software_fmea/software_fmea.tex index 1af6f36..f8966bb 100644 --- a/papers/software_fmea/software_fmea.tex +++ b/papers/software_fmea/software_fmea.tex @@ -373,13 +373,16 @@ Let us define any value outside the 4mA to 20mA range as an error condition. As a voltage, we use ohms law~\cite{aoe} to determine the voltage ranges: $V=IR$, $0.004A * \ohms{220} = 0.88V$ and $0.020A * \ohms{220} = 4.4V$. % -Our acceptable voltage range is therefore $$V >= 0.88 \wedge V<= 4.4 \; .$$ +Our acceptable voltage range is therefore + +$$(V \ge 0.88) \wedge (V \le 4.4) \; .$$ + This voltage range forms our input requirement. % We can now examine a software function that performs a conversion from the voltage read to a per~mil representation of the {\ft} input current. % -or the purpose of example the `C' programming language is used. +For the purpose of example the `C' programming language is used. We initially assume a function \textbf{read\_ADC} which returns a floating point %double precision value which holds the voltage read (see code sample in figure~\ref{fig:code_read_4_20_input}). @@ -684,8 +687,8 @@ We can now form a functional group with the {\dc} $RADC$ and the software compon \textbf{Failure} & \textbf{failure} & \textbf{Symptom} \\ \textbf{Scenario} & \textbf{effect} & \textbf{RADC } \\ \hline \hline - 1: $RI_{VRGE}$ & voltage & $OUT\_OF\_RANGE$ \\ - & outside range & \\ \hline + 1: $RI_{VRGE}$ & voltage & $OUT\_OF\_$ \\ + & outside range & $RANGE$ \\ \hline 2: $RADC_{VV_ERR}$ & voltage & $VAL\_ERR$ \\ & incorrect & \\ \hline \hline @@ -697,8 +700,8 @@ We can now form a functional group with the {\dc} $RADC$ and the software compon - 4: $RADC_{LOW}$ & ADC may read & $OUT\_OF\_RANGE$ \\ - & wrong channel & \\ \hline + 4: $RADC_{LOW}$ & ADC may read & $OUT\_OF\_$ \\ + & wrong channel & $RANGE$ \\ \hline \hline