SDR and Backfill

[Stefanos Kalaitzis]

Hi ... I am running weewx with sdr driver without any problem a long time now... but i noticed that when we have a power off and and rain falls for that period , when it comes up weewx doesn't back fill the amount of rain

i dont know if weewx stores the last value of rain total so then its easy to calculate the missing values or if i must do some changes to weewx.conf or sdr.py

thank u in advanced

[vince]

Where would weewx get the data from ?

If you lose power, your SDR isn't listening to the sensors, so how could weewx know what the weather conditions were ?

[Stefanos Kalaitzis]

I see your point and i fully understand it but i dont care for other values when we have power off except for rain 

For example my station calculate rain from rain total and if for example my rain total is 20mm  (weewx is calculating ,20 -20 = 0mm which is right, new total - old total) and we have power off ,and for that period 5mm fall , i think that the station because has batteries transmits 25mm rain total but of course sdr is off  .... So when weewx start again loop periods and gets data from sdr sorry the rain total will be 25mm and if it has saved the last value of rain total then it is 25 - 20 = 5 mm 

[Stefanos Kalaitzis]

i dont know if my english is good enough to understand ... but my console (i plug it to electricity power, no batteries) do that thing ... when it turns back on , it gives me the amount of rain that fell in this period

[vince]

(following up for others who might help)

Stefanos told me via email that his rain sensor reports a rain_total value that continually increments, so what he's looking to do is reflect whatever the sensor detected during a power outage and have an accurate total rain for the day.

The example he gave was:

• assume the total_rain counter started at 0 mm
• day-one 20mm of rain falls.  The sensor reports total rain = 20mm
• day-two 5mm of rain falls but there was a power outage while the rain was falling
• when the power goes back on SDR reads the sensor's new reading which correctly shows 25mm accumulated in total over all days
• so what he's looking for (I think) is how to set weewx up so day-two's rain shows 5mm (new total of 25 - old total of 20)

Hope this helps.

(Stefanos please correct me if I interpreted your email wrong)

[gjr80]

My vote is put the necessary equipment on UPS. Any other approach is going to be messy to handle no matter how you do it, what do you do if the power outage extends over a midnight boundary? How do you apportion rainfall across the outage period? 

Gary

[Stefanos Kalaitzis]

Thank you gjr80... Ups was my plan B ... I think if the power outage extends to the next day probably the amount of rain will passed to the next day too ... You will have one wrong saved record but your total will be correct... Anyway i thought that will be easier to do this but as you said other approach is going to be messy