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Increasing Wind Speed and Gusts

Topics about the Beta trials up to Build 3043, the last build by Cumulus's founder Steve Loft. It was by this time way out of Beta but Steve wanted to keep it that way until he made a decision on his and Cumulus's future.

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sperry russ
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Increasing Wind Speed and Gusts

Post by sperry russ »

I am still mainly running Cumulus1 on my XP netbook. For a few hours at at a time every day or two I am running the station on MX on the Raspberry Pi2 to test it out.


For the last 2 days I have been getting wind speed and wind gust spikes with MX. With wind at around 3mph on average I have had gusts of 86 mph, 34 mph and assorted others.

This is not and has not ever happened with Cumulus 1 on my XP machine. This is a fine offset emulated station by Charlie and is very stable for the last 1 1/2 years. So it is not the typical spikes that occur in the Fine Offset.

I can see in the MXDiags that there is an incrementally increasing wind speed going higher and higher. Don't know what to make of this
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Re: Increasing Wind Speed and Gusts

Post by steve »

Those are the figures that it's getting from the station. The rain counter has also reset to 1 tip, but then stays consistent. Temperature, humidity and pressure look reasonable. If this is a problem in MX, I don't know what the problem is - as far as I am aware, this doesn't happen with Fine Offset stations.

The difference between the way that the USB libraries used by C1 and MX work is that in C1, having requested a block of data at a particular address, just exits, and then receives the data asynchronously by event, 8 bytes at a time. In MX, having requested the data, the thread sleeps for 150ms, and then synchronously reads off the 32 bytes, 8 bytes at a time. Perhaps it is this difference which somehow causes incorrect data to be read. Longer sleep needed?
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Re: Increasing Wind Speed and Gusts

Post by sperry russ »

I have limited knowledge of programming and how the data is read. I have sent an Email to Charlie Gale with this info and hopefully he will get back to me soon and see what he thinks about this.

Thanks Steve.
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Re: Increasing Wind Speed and Gusts

Post by sperry russ »

I ran CumulusMX for quite some time on my Windows 8.1 machine today. I have not had any problems with spikes or anything.

I again connected it to my RaspberryPi 2 and immediately it started the wind spikes again. So it is confined to when CumulusMX and the Pi are running together. XP and the Windows 8.1 work fine.
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Re: Increasing Wind Speed and Gusts

Post by steve »

Possibly a timing issue, then. Or perhaps just something different about the way the Linux USB code works.
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Re: Increasing Wind Speed and Gusts

Post by Charlie »

Sorry folks - have been travelling and just returned. I'll try to poke a bit this week, but I have not even started to look at MX as I don't own a PI. I do agree with Steve that this is likely a timing issue, but can't imagine why it should be so.
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Re: Increasing Wind Speed and Gusts

Post by sperry russ »

When you are saying timing, what does that involve? Is it how the data is read communicating with the USB? Or timing to do with some other issue?
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Re: Increasing Wind Speed and Gusts

Post by Charlie »

sperry russ wrote:When you are saying timing, what does that involve? Is it how the data is read communicating with the USB? Or timing to do with some other issue?
As Steve mentioned, likely the 150 ms sleep isn't long enough. My stations will take a bit longer to send the data than the Fine Offset, as it has more error checking and structure in the code. Since it's microcontroller based, any software change would require either specialized programming hardware and software to put the new load in place, or replacing the microcontroller.
I need to dig the code out of archive, as it hasn't changed in many years. Hopefully I can get to it on the weekend - but it's really about understanding the issue, not fixing it as I don't have a method to validate a change, or to deliver that change to you.
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Re: Increasing Wind Speed and Gusts

Post by sperry russ »

Okay, thanks Charlie. Looking forward to see what you find out.
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Re: Increasing Wind Speed and Gusts

Post by sperry russ »

Charlie checked the code on the Windblown Station and this is what he said in an email:

"I went through the code (thought I had posted, but guess I did not). There are no specific timers or delays when I send the data, and the timing is actually close to the Fine Offset device. Since I don't use delays, I can't make it go faster by removing them. So my guess is that to fix this Steve will either have to increase his wait time, or change to a module that flags when it's ready, like the windows version of the USB interface."

I am not sure what all that means but I guess you do Steve.

Anyhow I was looking at other settings to see if I could spot anything else. One thing I saw was that I have set in the Station options: Calculate 10-min wind average. I unchecked that and pressed the Save button and it would not allow me to save it. When I change options in the other pages it allows me to save and gives a confirmation. But on the Station Settings page nothing happens when I try to save.

Don't know if that has anything to do with it.
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Re: Increasing Wind Speed and Gusts

Post by steve »

In the latest (unreleased) code, I've made the 'wait period' configurable, so when I realise that, you'll be able to experiment with increasing it. I can't change to a different component for handling the USB interface, as there isn't one.

Regarding not being able to save the station settings. Are there any red boxes and text on the screen, as described in the MX FAQ: "If a settings screen shows red contents (red text and red boxes), invalid data is present which must be corrected before the form can be sent. One or more items on the page will have an error message."
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Re: Increasing Wind Speed and Gusts

Post by sperry russ »

I am looking forward to trying the new release. Hope it solves the problem.

I found the error in the station settings. Somehow one of the degrees in the Lat Long got changed when I copied the data over. When I corrected it then I was able to save the page.

Thanks.
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Re: Increasing Wind Speed and Gusts

Post by steve »

I've uploaded build 3027. To change the read timeout, add a line to the [Station] section of Cumulus.ini, before starting Cumulus:

FineOffsetReadTime=150

The 150 in the example is actually the default, so you need to experiment with values higher than that. The value is in milliseconds.
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Re: Increasing Wind Speed and Gusts

Post by sperry russ »

Okay. Thanks very much Steve. I will let you know how it does.
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Re: Increasing Wind Speed and Gusts

Post by sperry russ »

Well, sorry to say that changing the timing did not help.

I tried from 200ms in 100ms increments all the way up to 1000ms and it still gives the erroneous wind readings. I noticed this time, that every time I cleared all the records out and started fresh with a new ms setting that it always gives the erroneous reading of 86.6mph on gusts and on wind speed. That speed seems to be the one most often given in error.

Causes a lot of grief when I hook it back up to my windows machine again cause it changes all the records on wind to the erroneous readings in every file so I have to go and correct all of them.
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