I am afraid that you didn't answer the question.
humidity is returned as absolute or relative. It doen't make much
difference around 25'c, but its 33'c in the shade today.
So, it's a rolling average, over how many cycles?
open port, read from it once every 10 seconds.
the serial cable becomes unplugged, or someone chops through it with a machete.
rh02_get_value hangs forever, it never realises that nobody is talking to it and keeps sending "0x04" or "0x05"
replug in the cable, replace it, whatever.
rh02_get_value continues as if nothing has ever happened.
indeed, the cycle returned by rh02_get_cycle has not noticed either.
this means that unless you engage in black magic like putting an alarm around all calls with a timeout, you are never going to notice an equipment failure.
Unfortunately I don't have time to roll my own, as these go live at the beginning of next week driving around Tokyo extorting you to drink <insert large well known brand here>
It is, however, something people using the Dll's should be aware of.