Bug: Channels get mixed after some time

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Martin Lintzgy
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Re: Bug: Channels get mixed after some time

Post by Martin Lintzgy »

We can confirm that opening Edge on widows 10 does indeed provoke channel swapping.
From the technician who carried out the test.

"I went out to the lab where the piclog is running, monitoring UUT's , and Edge is on this Laptop, but doesn’t seem to be running. I had a look on Task Manager.
There is one unit with high current, 4mA. approx.. it stands out visually, and as an experiment, when I opened up the Edge app…..the 4mA. unit jumps channel. I did it 3/4 times and it jumped each time.
However, Edge doesn’t seem to be on in the background"

Martyn
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Re: Bug: Channels get mixed after some time

Post by Martyn »

This is not specifically due to Edge, but more that launching Edge is a CPU intensive process, and can also be seen when the O/S decides to do updates.

What is happening is that the driver is not given sufficient time resources by the O/S to read values from the device and so the devices on board memory fills.

What would be the correct course of action when this occurs, as there will be missing data. Would it be better to acknowledge that there has been a problem and leave gaps in the data, or use some form of interpolation to fill in the gaps.

I can't guarantee how easy any solution will be to implement in the codebase, but can pass on your thoughts to the developers.
Martyn
Technical Support Manager

Martin Lintzgy
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Re: Bug: Channels get mixed after some time

Post by Martin Lintzgy »

Sounding like a buffer overrun problem in the driver.
Your comment
"I can't guarantee how easy any solution will be to implement in the codebase, but can pass on your thoughts to the developers"
Says to me that you are not taking this problem seriously. All very well shouting from the hilltops about your new Cloud service, rather like selling a car with a faulty engine but, hey, it features exiting new cupholders.

We want a logger that will reliably log 16 channels over a few weeks, where the channels logged dont get randomly mixed up!!
If there are data readings skipped because of insufficient resources, then so be it-- Random Channel swapping makes the product 100% useless!.

mchamley
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Re: Bug: Channels get mixed after some time

Post by mchamley »

I agree with Martin, far better to have missing data than swapped channels, and missing data is also preferable to interpolated data which risks being misleading. And the comments about advertising features versus supplying something reliable are spot on - I'd even rather fiddle about logging the data in a terminal session with some clunky solution over RS232 than have something fancy that doesn't get the fundamentals of reliably logging data right.

mchamley
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Re: Bug: Channels get mixed after some time

Post by mchamley »

It would be nice to know whether there's any update on this. We've given up on Picolog 6 now and have written our own Python scripts that just write the data to csv files to reduce the CPU and memory usage, in order to reduce the probability of running into this data corruption issue. Of course, knowing that the fundamental cause of the problem is still present doesn't fill us with confidence, so we still want this to be fixed, if Pico ever plans to give it any priority. At this point it doesn't look sensible for us as a business to remain loyal to Pico's products.

Calo0
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Re: Bug: Channels get mixed after some time

Post by Calo0 »

I am currently facing the same issue.
The channel mixing is clearly due to a high CPU usage (not sure about memory) as it happens each time a CPU peak occurs, when I open a browser or launch a programm with visual studio for eg.

Image

Reducing the CPU usage by all means could be a solution, but it feels uncomfortable knowing anything could go wrong if the CPU usage goes up for any reason...

vladislav.mitev
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Re: Bug: Channels get mixed after some time

Post by vladislav.mitev »

Hi All!
We are experiencing similar problem to what has been discussed here. Hopefully, now this issue has a solution.
Our setup is the following:
USB Version: USB 1.1
Hardware Version: 1
Variant Info: PicoLog1012
Calibration Date: 09Mar17
Kernel Driver Ver: PICOPP.SYS V1.0

Channels to sample: 2, 3, 4, 5, 6
SamplesPerChannel: 1000
DataCollectionBlockUs: 1000000µs
SignalSamplingIntervalUs: 1000µs
ActualSamplingIntervalUs: 200µs
SamplesPerChannelForBuffer: 10000

We have developed a piece of software (C# .net framework 4.8 ) based on the programmers guide (https://www.picotech.com/download/manua ... g-en-3.pdf) and the C++ examples provided with the driver (dll version is 2.0.82.3072).

We are using 5 of the channels (2-6) and we observe that after some time received values are rotated:
BEFORE: CHN 02 = 0684mV; CHN 03 = 0676mV; CHN 04 = 0021mV; CHN 05 = 0034mV; CHN 06 = 1297mV;
AFTER: CHN 02 = 0679mV; CHN 03 = 0019mV; CHN 04 = 0031mV; CHN 05 = 1297mV; CHN 06 = 0681mV;

As you see values' places are swapped with one to the left. Somethings this swap is with two places.
The only thing we have noticed is that this behavior is highly dependable on the no_of_values parameter passed to the pl1000Run method. The higher the values the later the problem occurs. And eventually a high enough value seems to get rid of the problem (e.g. 10 x numberOfChannels x idealNumberOfSamplesPerChannel) which is not according to the documentation.
Following is a quote from the documentation:
"The noOfValues argument passed to pl1000Run() must be sufficient to
ensure that the buffer does not overflow between successive calls to pl1000GetValues(). For example, if
you call pl1000GetValues() every second and you are collecting 500 samples per second, noOfValues
must be at least 500, or preferably 1000, to allow for delays in the operating system."
With the given settings it takes about 22 minutes before the values start to rotate.

We have made tests with the C example provided at github (https://github.com/picotech/picosdk-c-e ... ter/pl1000) and the issues is reproducible even faster.

Any help on the issue would be highly appreciated.

jkjelsbak
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Re: Bug: Channels get mixed after some time

Post by jkjelsbak »

Hi,
I have this issue on a new installation
Win 10 8GB
PicoLog 6.2.8
PicoLog 1012

Please, does anyone know a fix?

Very best regards

Jens Kjelsbak

Martyn
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Re: Bug: Channels get mixed after some time

Post by Martyn »

The channel swap issue was fixed in PicoLog 6.2.8 so if you are still experiencing this can you make sure that you have reset the configuration backing up any data you need before you do this, and if this doesn't resolve the issue then email support@picotech.com for further assistance.
Martyn
Technical Support Manager

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