The access should be reporting to Wunderground at about 20 sec. and not 38.
You mean 36?
And your saying the access reports faster at 20 sec. intervals??
It's probably 18 seconds. That's the wind data update rate for the 5n1.
In the SmartHUB, they chose 36 seconds for the update because that's how long it takes to get a complete set of weather data. The 5n1 emits 2 types of data packets alternating every 18 seconds. One has wind speed, wind direction, and rainfall data. The other has wind speed, temp, and humidity.
If you don't send wunderground a complete set of data, things can get screwy, so that's why they settled on 36 seconds. However, if you buffer the data you can construct a complete data set every 18 seconds it will make wunderground happy. I was doing it years ago with my programs and scripts so it definitely doable.
I imagine that's what they might be doing in the Access for the 5n1. When I get my "production" Access I'll be able to verify it in the data flow.