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Serial not as fast as USB????

Posted: Mon Mar 02, 2009 3:48 am
by AAMFlyer
I just switched over to a Alix3D2 and also switched back to a serial connection.....before I was Serial to a USB converter.... Watching my sensor data the update time seems to be significantly longer with serial....

With USB it would update as often as I hit refresh....but with serial it sometimes takes a minute between last signal updates... The Davis is supposed to receive every 2.5 seconds - so it's not really getting and transmitting live data with a serial connection.....any reasons why - looks like I need to switch back to USB....

Does it still transmit if the data doesn't change?

Here is a screen shot showing almost a minute on all sensors...



Thoughts....

Re:Serial not as fast as USB????

Posted: Mon Mar 02, 2009 7:18 am
by AAMFlyer
Here it is...notice the time on last signal....never saw this with USB....

Image

Re:Serial not as fast as USB????

Posted: Tue Mar 03, 2009 5:13 am
by AAMFlyer
Watching further - possibly seems to update only when there is a change....like with wind that changes constangly....interesting... Hasn't missed any high wind marks yet....so perhaps it's fine...

Re:Serial not as fast as USB????

Posted: Tue Mar 03, 2009 11:23 am
by skyewright
AAMFlyer wrote:Watching further - possibly seems to update only when there is a change....like with wind that changes constangly....interesting... Hasn't missed any high wind marks yet....so perhaps it's fine...
I don't have a VP, but I've a vague recollection of Boris introducing something to keep down the volume of redundant (i.e. no change) data recorded from the VP due to its high reporting rate. Maybe something like "only write the sensor data if the value changes or if it's at least a minute since the last write for that sensor"?

But even if my recollection is correct, I thought that change was ages and ages ago...

Re:Serial not as fast as USB????

Posted: Tue Mar 03, 2009 3:34 pm
by AAMFlyer
That would make sense from what I'm seeing by simply hitting refresh - it appears to only update when there is a data change when I'm watching the wind....