After some experimentation, I found that the radiation value in the VP2 LOOP packets does, indeed, normally change every 50-52 seconds, but, perhaps about a fifth of the 'gaps' are a *multiple* of that time - most often 100+ or 150+ seconds, but occasionally more than that (I saw one 250+ second 'gap'). I saw this under conditions of variable sunshine and clouds when it seemed unlikely that the actual radiation value would have been precisely constant for that length of time, so I am not sure exactly what is going on. In any event, I am revising the code I am using on the basis of doing the threshold calculation when the radiation level changes, but at least every minute, if it remains constant for more than the normal 50-52 seconds..
On Sunday, June 5, 2022 at 12:33:47 PM UTC-4 jterr...@gmail.com wrote: > I think it is also OK to do an average for every 30 seconds. It depends > also on the weather station used. > For instance, a Davis Vantage Pro 2 ISS transmits an updated solar > radiation value every 50 to 60 seconds. So with this weather station, even > a 1 minute average would not be very different since anyway the solar > radiation values of the LOOP packet are the same for at least 50 seconds.! > > Le 5 juin 2022 à 18:02, 'Peter Fletcher' via weewx-user < > weewx...@googlegroups.com> a écrit : > > I chose to average the LOOP radiation readings and only to do the > threshold calculation and make the sun/no sun determination every 30 > seconds because I thought doing it on every LOOP might overload LOOP > processing (I am running weewx on a Pi 3B, which is also doing a few other > things which use the CPU). If this is an unnecessary concern, as it may > very well be, your modified code is much cleaner than mine. > > On Saturday, June 4, 2022 at 12:41:08 PM UTC-4 jterr...@gmail.com wrote: > >> It is a very good idea to calculate the sunshine duration for each LOOP >> packet and sum these values to make the final archive sunshine duration. I >> have modified my script accordingly : >> https://github.com/Jterrettaz/sunduration. >> The logic is the following : for each received LOOP packet, the >> radiation is compared to a calculated threshold. If the radiation is above >> the threshold value, the sunshine time for the LOOP packet is equal to the >> time elapsed between the previous loop packet and this packet (most of the >> time 2 seconds with a Vantage Davis Pro). >> The final archive sunshine duration is the sum of all the LOOP value >> within the archive period. >> Le vendredi 3 juin 2022 à 21:59:36 UTC+2, Peter Fletcher a écrit : >> >>> That makes some sense when you are getting data from an 'external' >>> sensor, though there are (IMHO) simpler ways of doing it. weewx already has >>> access to the LOOP radiation data from the VP2, so handling the processing >>> and data storage within weewx makes more sense to me in this case. >>> >>> On Friday, June 3, 2022 at 3:24:23 PM UTC-4 vince wrote: >>> >>>> On Friday, June 3, 2022 at 11:17:00 AM UTC-7 Meteo Oberwallis wrote: >>>> >>>>> if the interval of Weewx and the data logger is set to 10 minutes, I >>>>> would have liked to read the value of the solar sensor every minute and >>>>> then write it into a separate .sdb database as possible sunshine. >>>> >>>> >>>> Personally I'd use an external program called via cron and posting a >>>> message to a MQTT topic. Have weewx subscribe to that topic to get the >>>> data into your db. >>>> >>>> This is how I used to get my DS18b20 temperature sensor data into weewx. >>>> >>>> > -- > You received this message because you are subscribed to a topic in the > Google Groups "weewx-user" group. > To unsubscribe from this topic, visit > https://groups.google.com/d/topic/weewx-user/19ylVTRqbh4/unsubscribe. > To unsubscribe from this group and all its topics, send an email to > weewx-user+...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/weewx-user/0e631671-0a74-4963-9f1c-e5f81bc7c366n%40googlegroups.com > > <https://groups.google.com/d/msgid/weewx-user/0e631671-0a74-4963-9f1c-e5f81bc7c366n%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > > -- You received this message because you are subscribed to the Google Groups "weewx-user" group. To unsubscribe from this group and stop receiving emails from it, send an email to weewx-user+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/weewx-user/f0ecc86f-a615-4a24-a43f-ee0d3963b8adn%40googlegroups.com.
