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Dithering is not executed with external lin_guider

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Replied by Jan Hruby on topic Dithering is not executed with external lin_guider

Didn't mention it earlier but I run whole Kstars on RPi, not just server. Only QHY9s is physically present and mounted, rest are simulators (telescope, focuser, guidecam) and guiding QHY5L-ii-m stays unconnected as being used by Lin guider. I'll try tonight with some changes and maybe keep an eye on it for a while... it's windy anyway.

btw QHY9 filterwheel still gives me requested filter +1 making unreachable 1st filter (1st returns #2, 2nd returns #3, 3rd returns #4, 4th returns #5 and 5th returns confirmation of #5 with ordinary delay but without rotating filters leaving effectively last called filter in the path). There must be some tiny hitch in the code since filterwheel works fine in EZCAP.

One last think why I prefer LG to integrated guiding interface. There is full manual control over gain and white point in linguider but in INDI it's running on auto. When there is significant change in star contrast/brightness Kstars freezes for a while when processing last image and eventually loosing guiding star or making panic corrections => guiding aborted. also reticule in LG is user-friendly as I can mark position of guide star and return there later after making some work around the mount (like fixing hand controller as last night) and it shows directions of RA and DEC.
7 years 1 month ago #14989

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Replied by Jasem Mutlaq on topic Dithering is not executed with external lin_guider

I pushed a fix for the QHY filter wheel, should be in PPA tomorrow.
The following user(s) said Thank You: Jan Hruby
7 years 1 month ago #14990

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Replied by Jan Hruby on topic Dithering is not executed with external lin_guider

Great, looking forward trying it.
7 years 1 month ago #14995

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Replied by norikyu on topic Dithering is not executed with external lin_guider

For problem #14929, I fixed lin_guider.

Line 996 of lin_guider_pack / lin_guider / src / lin_guider.cpp.
-         answer_sz = snprintf (answer, answer_sz_max, "Long time cmd finished");
+         answer_sz = snprintf (answer, answer_sz_max, "OK");
Lin_guider will now return "OK" after dithering.
I will wait for the correct fix by rumen.

However, the problem of #14978 has not been solved yet.
My Ekos sometimes stops as "Dither ...".
This does not always happen, it seems to be caused by bad timing.
7 years 1 month ago #15082

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Replied by Jasem Mutlaq on topic Dithering is not executed with external lin_guider

Transient timing issues are hard to track down, but if you turn on logging it might help us somehow. Of course, if you can debug and find out where it gets stuck exactly that would be great.
7 years 1 month ago #15083

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Replied by rumen on topic Dithering is not executed with external lin_guider

Hi guys,
where are problems #14978 and #14929 described?

What comes to the return "OK" fix it can not be accepted for several reasons.
First there are several pieces of software relaying on that and we can not change it, so it should be changed on Ekos side. Second dither command is not recommended as you have no idea if it was successful or not. That is why it does not say OK or Error. It is kept only for compatibility purposes. There is another non-blocking command for dithering: DITHER_NO_WAIT_XY. It returns immediately and if successful you can check if it is completed or not with GET_DISTANCE which will give you the distance between the target and current position.
What is problem #14978? :) I do not see it anywhere...
Rumen
Last edit: 7 years 1 month ago by rumen.
7 years 1 month ago #15088

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Replied by norikyu on topic Dithering is not executed with external lin_guider

Hi, rumen.
Thank you for detailed explanation.
I understood the specification of lin_guider.
It is said that the response of the DITHER command does not inform of the success of dithering.
I will undo my modifications.
Then fix it so that Ekos ignores the response of the DITHER command and try it.

I am debugging Kstars on communication with lin_guider.
I will report when I found something.
7 years 1 month ago #15103

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Replied by rumen on topic Dithering is not executed with external lin_guider

Hi,
if you are willing it is better to use the commands I have mentioned. It is not that simple with DITHER command, What this command does is do the DITHER wait some amount of time calculated by the guide rate and the dithering range and return. However if the calibration is not performed it will fail with "Error:..." or if in progress with "Busy:...". These are precondition checks. So you can not ignore the output. However there is no way to be sure if it is finished successfully or not if it started it will just wait some time and return amusing that the mount is settled. So I was not precise in my previous post. You can be sure if it says "Error" or "Busy" that that it did not succeed, but there is no way to be sure if it really succeeded, however you can safely assume success if it does not say Busy and Error.
Best way is to use DITHER_NO_WAIT_XY, and poll while GET_DISTANCE returns values within a specified range.

Rumen

p.s. Lin-guider is close to 4.2.0 with driver updates and zoom of the image view, Also there may be SBIG camera support but most likely it will wait for 4.3 as I do not have much time for that now.
Last edit: 7 years 1 month ago by rumen.
7 years 1 month ago #15104

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Replied by norikyu on topic Dithering is not executed with external lin_guider

Thanks for your advice.It will be helpful.
Lin_guider is very lightweight and easy to use, so I like it very much.
I am looking forward to the new version.
7 years 1 month ago #15119

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Replied by norikyu on topic Dithering is not executed with external lin_guider

I looked at the debug output of Ekos.

When I dumped the response from lin_guider I noticed that I was receiving an irregular data stream.
A sample of the received data stream is as follows.
Guide: "\u0002\u0000\u000E\u0000\u000B\u0000\u0000\u0000-0.43 -0.02"
Guide: "\u0002\u0000\u000E\u0000\u0000\u0000\u0000-0.37 0.51"
Guide: "\u0002\u0000\r\u0000\u0002\u0000\u0000\u0000OK"
Guide:  "LinGuider::processResponse SET_DITHERING_RANGE"
Guide: "\u0002\u0000\u000E\u0000\u000B\u0000\u0000\u0000-1.37 -0.32"
Guide: "\u0002\u0000\u0004\u0000\u0002\u0000\u0000\u0000OK"
Guide:  "LinGuider::processResponse DITHERING"
Guide:  "Dithering completed successfully."
Guide:  "Guiding resumed."
Guide: Capturing frame...
Guide: "\u0002\u0000\u000E\u0000\t\u0000\u0000\u00000.03 0.87"
Guide: "\u0002\u0000\u000E\u0000\t\u0000\u0000\u00000.49 0.85"
Guide: "\u0002\u0000\r\u0000\u0002\u0000\u0000\u0000OK\u0002\u0000\u000E\u0000"
Guide:  "LinGuider::processResponse SET_DITHERING_RANGE"
Guide:  "Failed to set dither range."
Guide: "\u0000\u0000\u0000-0.27 0.64"
Guide:  "Invalid response."
Guide: "\u0002\u0000\u000E\u0000\t\u0000\u0000\u00000.14 0.63"
Guide: "\u0002\u0000\u000E\u0000\u000B\u0000\u0000\u0000-0.19 -0.86"
Guide: "\u0002\u0000\u000E\u0000\u000B\u0000\u0000\u0000-0.31 -0.49\u0002\u0000\r\u0000\u0002\u0000\u0000\u0000OK"
Guide: "\u0002\u0000\u000E\u0000\u000B\u0000\u0000\u0000-0.31 -0.49"

A normal response is:
Guide: "\u0002\u0000\u000E\u0000\u000B\u0000\u0000\u0000-0.43 -0.02"
Convert to byte sequence:
0x02 0x00 0x0e 0x00 0x0b 0x00 0x00 0x00 "-0.43 -0.02"
It has an 8-byte header and text data.


It shows a pattern of irregular response.
Guide: "\u0002\u0000\u000E\u0000\u000B\u0000\u0000\u0000-0.31 -0.49\u0002\u0000\r\u0000\u0002\u0000\u0000\u0000OK"
Convert to byte sequence:
0x02 0x00 0x0e 0x00 0x0b 0x00 0x00 0x00 "-0.31 -0.49" 0x02 0x00 0x0d 0x00 0x02 0x00 0x00 0x00 "OK"
The two command responses are consecutive.

Another pattern is:
Guide: "\u0002\u0000\r\u0000\u0002\u0000\u0000\u0000OK\u0002\u0000\u000E\u0000"
Convert to byte sequence:
0x02 0x00 0x0d 0x00 0x02 0x00 0x00 0x00 "OK" 0x02 0x00 0x0e 0x00
After the normal command response, the next command response fragment "0x02 0x00 0x0e 0x00" is attached.


Responses from lin_guider are handled by LinGuider::readLinGuider().
The response is read and processed from the socket using QTextStream, but it is assumed that it receives one command response from lin_guider.
It can not be handled correctly if multiple command responses receive consecutive data streams or responses with fragments.

This problem is unlikely to occur in high-speed network, high-speed CPU environment.
However, there is a possibility of occurrence in any network.

There is also a command response in which the header is broken.
For example,
Guide: "\u0002\u0000\u000E\u0000\u0000\u0000\u0000-0.02 0.90"
Convert to byte sequence:
0x02 0x00 0x0e 0x00 0x00 0x00 0x00 "-0.02 0.90"

There is only 7 bytes of header, and there is no length of text data.
Is the CRLF code (0x0d / 0x0a) automatically removed by QTextStream?
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7 years 1 month ago #15120

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Replied by rumen on topic Dithering is not executed with external lin_guider

Hi,
One can not expect that separate TCP packets will be read in separate reads. It is a stream so it should be read as a stream too. Reading should be done as follows: read the first 2 bytes (used as linguider identifier) read next 2 bytes (command ID) and next 4 as length, then read "length" bytes and use them as command response. then next should be linguider ID and so on...

I am not an expert in the thousands of the QT classes but the name QTextStream suggests that it is not a raw stream but text stream. Also if readLine is used it removes \n and \r. the last resonance has length 10 which is "\n" and is obviously removed.

So looks like this part should be reworked

Rumen
Last edit: 7 years 1 month ago by rumen.
7 years 1 month ago #15127

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Replied by Jasem Mutlaq on topic Dithering is not executed with external lin_guider

Thanks noriq for the details. Ok it can be read as raw data. Try to do this.
while (tcpSocket->atEnd() == false)
{
QByteArray data = tcpSocket->read( 8 );
....etc
}

then process the data. Try to see if that works
Last edit: 7 years 1 month ago by Jasem Mutlaq.
7 years 1 month ago #15142

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