Alarms/Emails

[Mapantz]

I'm still confused with the alarms.

It's quite windy here, so as a test I set the alarm threshold to 25mph. It went off when 25mph was reached, but it kept going off even though I wasn't hitting 25mph anymore. I presume that's because the alarm is going by the high 10 minute gust value?

I set a latch and it stopped that. But then I just had a gust of 30mph, and no alarm sounded.

I just thought it work simply sound an alarm whenever wlatest matches the threshold, and that's it.

[mcrossley]

Using a "greater than" alarm as an example to avoid saying greater than/less than all the time!

The alarm will trigger every time the data exceeds the test value. Once triggered it will not trigger again until the data falls below the test value, then rises above it again.

If you have a data point that oscillates, then it can repeatedly dip below/above the test value, you will then get multiple alarm triggers. This is where you can configure a "latch" time. Once triggered the alarm will stay in the triggered state until the latch time expires, you then only get one alarm raised within the latch period.

If you want to monitor peak gust speeds then wlatest is probably not a good data point to use. For your Davis it will change every 2.5 seconds. The chance of it "bobbling" around the trigger value is high. It would be better to use the wgust value, then it will only trigger the alarm a maximum of once every 10 minutes.

[Mapantz]

I'm just using the built in alarm on the dashboard. The alarm keeps sounding even though the wind speed isn't hitting the threshold.

[mcrossley]

Sswitch on debug logging and post a log file

[Mapantz]

OK, I've set the alarm to sound when a gust is > 25mph.

The alarm keeps going even though the wind speed is much less than that. It seems the alarm keeps going because the 10 minute gust is above the threshold.

I was under the impression that the alarm will simply sound once when the wind speed hits the threshold, not with the 10 minute high gust.
If I set a latch, the alarm will never go off, even if the daily high gust is greater than the previous one.

I normally set the threshold to 45mph. In very windy conditions, I might hit that once every 15 minutes here, so it would be nice to have the alarm go off, but not continue due to the 10 minute high gust value. In my mind, that makes the most sense.

20241204-203116.txt

[mcrossley]

I just looked at the gust alarm and tested it. It is triggered by the latest wind value - so a different value every 2.5 seconds on my WLL. I set it at 20 mph and it is pinging all the time, because the live values keep dipping.

EDITED:
To make it usable you will need to set a latch value to whatever period you think appropriate. I just tested 12 minutes 0.2 hours) and it works as expected.

BUT, I see with the WLL there is a unique difference to other stations. It also once a minute checks the WLL High Gust value against the MX gust value to cater for lost broadcast packets. This also tringgers the gust alarm, so you were right, the 10 minute (by default) gust value from the station is also coming into play.

Setting a latch for 10 minutes or more will fix that.

[Mapantz]

But if it's dipping and not hitting the threshold, why would it keep pinging?

[mcrossley]

See my edited reply above!

[Mapantz]

Yep!

I set it to 0.2 and it does exactly what I wanted. Thanks Mark!

I didn't realise the latch times could be adjusted to tenths.

PS: Should be interesting with the forecast wind speeds tomorrow night and in to Saturday.

[mcrossley]

You can use 2 decimals if you want to specify to the minute. The trigger will effectively round up fractional minutes to the next whole minute.