I am speaking about an industrial equipment that is generating gas. It is under certification test (CE marking) IEC 61010 in a third party lab.
In the device there is an over temperature detection mechanism, which is aimed at stopping the device. Here is how it works:
- Temperature sensor (LM335)
- A uC is reading the temperature every seconds
- After reading it compares its value with a hardcoded threshold, and if temperature is over the threshold, it raises the alarms and launches the stop procedure.
- In a couple of seconds it goes in stand-by mode.
The lab making the certification tests tells us that it since the over temperature detection is made by mean of software, it is not reliable. And because it is not reliable, it is not compliant with CE Marking.
They also add that "It is considered by the testing labs that a software is all but a reliable component. Non exhaustive list: infinite loops, data corruption, EMC perturbation ..."
It sounds completely extrapolated to me.
Is the testing labe right? Are software/firmware considered as not reliable? If no, how shall I prove the lab that we designed our firmware component to be reliable?