15 minutes period time to graphic widget speedomer?

Hello,

For now, we only support astronomical periods minute/hour/day/month.
You can export data to CSV file from Data menu and calculate other periods in EXCEL yourself.

Okay, but is real time mean one minute for speedometer or just one impuls for example? 

Didn't quite understand the question.

The widget-speedometer is updated in real time, every 5 seconds.

Do you want the widget to update only once a minute? I'm afraid it won't work until then.