Cumulus Support

I upgraded to b3141 on 31st July. At just after 1500 BST today I restarted MX for the first time since the upgrade and noticed that the dew point values were far too low. On checking my VP2, the values shown in the console are okay, so my first fear of a misbehaving RH sensor has now gone away I use a quadratic formula to correct overreads and underreads in my VP2 humidity sensor, thanks to the ability to do this through MX's Offsets settings. My next step in tracking down the problem was to check the offset values for RH. The value for HumMult2 had been reset to 0. I found the correct value from backup copies of Cumulus.ini and manually entered it through the interface. Sure enough, the dew point values were then sensible.

Unfortunately that isn't the end of the story, as on restarting MX the HumMult2 value has reverted to 0.

On looking in Cumulus.ini there was no sign of the HumMult2 parameter. Therefore I shut down MX and manually added HumMult2 and its value.

I haven't dared to restart MX again since performing the last step! While I was in Cumulus.ini I couldn't see any other offsets ending in "2". Perhaps there's a problem in the code that rewrites Cumulus.ini?

Good catch, yes, it reads the value correctly, but does not write it back. Adding into your Cumulus,ini should fix it for now until I can get the next release out.

Thanks Mark. If I have to restart will I need to pop HumMult2 back in the ini file first?

You shouldn't but please check. On the first run of v3.12.0 it will re-write Cumulus.ini to clean out old settings, but subsequent runs should not as it is now already cleaned up - if I coded it right!

So if you added the value back in to the Cumulus.ini created by v3.12.0 you should be OK.

Yes, it has survived a restart. I'm happy now

I didn't realise that Quads had been introduced; shows I've missed it in the details.

Here's a thought on the settings page though.
Rather than having the offsets & multipliers sections, what about just 3 fields of each reading.

a, b & c along with the well known "Corrected Value =ax²+bx+c"

Realistically if you are someone who'd play with the settings, you'd have a handle on the math.

Even wrap it with the warning,
Here be dragons! Only alter these settings if you understand what they do.

Cheers.

Phil23 wrote: ↑Mon 02 Aug 2021 10:46 pm "Corrected Value =ax²+bx+c"