Temp/dewpoint Randomly Dropped to Zero

[hemmits]

Any reason why the temperature and dewpoint would drop to zero for a few minutes in Cumulus? This is the first time I have ever had this issue. I use WeatherLink Live to collect my data and that device in addition to three other Davis consoles did not report these numbers. Could this be a Cumulus software bug? I have attached an image of the temperature graph.

[RayProudfoot]

I had the opposite problem yesterday after installing a new ISS. Temp rose 5°C in 5 mins. Mine lasted until I reset the console.

Take out one battery, remove power cable and remove data logger. Wait 30 secs and insert in reverse order. Cleared my problem

If yours persists it’s probably something else.

[mcrossley]

There probably isn't anything to see now, but please post your MXdiags log file that covers that period, along with the date/times it occurred.

I will probably need a log with data logging enabled. But if it was a one-off...

[HansR]

This looks typically like a short stop of CMX. You won't find it in the logs, just the chart.
I have this when I backup. A backup of minde consists of a shutdown of CMX, backing up (max 90 seconds) and starting up CMX. This causes a drop in the charts like this but because it is within 5 minutes (logging interval) you don't see anything in the log.

[hemmits]

Attached is a snippet of the log from that period. The issue started at 22:33 and ended at 22:35. 22:33 and 22:34 had the bad data points. All data 22:32 and before and 22:35 and after were fine.

[hemmits]

I understand that errors like this can happen, but it would be nice if Cumulus could have some sort of data QC to avoid sending out bad data to the world. The ob below (taken from a CWOP provider) was sent out to all the data providers that I have enabled.

Time Temp(F) Dew(F) WB RH WS Gust Dir Pres Alt Precip
22:34 0.0 -78.3 -4.0 1 3.0 6.0 SSW 25.69 29.47 0.0

[freddie]

There is QC of sorts - spike settings. Use with caution.

[hemmits]

There is QC of sorts - spike settings. Use with caution.

Thanks freddie. I almost forgot about the spike settings. However, I live in an area where extreme temp fluctuations are a common occurrence, and it would be difficult to figure out a good value to use.

[mcrossley]

All I can see from the log is...

Around that time you started to get some missed broadcast packets from the WLL, which looking at the packet counts is the first time in that run of CMX.
During the period 22:32:17 to 22:34:47, when CMX requested the current conditions from the WLL, the temperature and humidity values were "null"

I was pretty sure CMX did a check for and ignored null values. But I'll take another look the code...

[mcrossley]

... how wrong I was. temp and humidity are not checked for null.

I'll get that decode fixed.

[HansR]

In general or specific for wll?

[mcrossley]

Specific to the WLL

[hemmits]

Very good, thanks Mark!