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INDI Library v2.0.6 is Released (02 Feb 2024)

Bi-monthly release with minor bug fixes and improvements

Meridian Flip - EKOS/Onstep Slews to last star

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I've been experimenting with automatic meridian flip and I am not sure if this is a bug in EKOS/INDI. When I do meridian flip, the mount slews to the last star I align or the last star I slew to rather than the current star it's tracking.

This is from a thread on the OnStep forum: onstep.groups.io/g/main/topic/meridian_f...20,84839240&jump=1So, I've been experimenting with the suggestion made by Chad about setting KStar as master time/location and I am having an odd issue. I am having odd issues regardless of what I set in the time/location settings in Kstars. Sometimes I get a meridian flip to happen but most of the time it slews to the last star I used for the alignment procedure. I've checked time and location settings before I do anything and they look correct. The only odd thing I see is that KStarts uses the negative value for longitude when west of prime meridian while Onstep uses positive values west of meridian but even when Kstars sends for example +237 as longitude, Onstep shows +123 so it's correct for my location. The time is set correctly also in both KStars and Onstep (confirmed on the Onstep webpage).

Here's what I've been doing.

-Connect to Onstep using EKOS
-Kstars sets the time/location on the connection
-Set the Minutes Past Meridian Parameters (8 minutes). I have default settings for Pause at Home to OFF and Preferred side to East so they're already set from config.h
-Go to Align tab in INDI, Choose 1 star, Click Start Align.
-Using Kstars right-click on bright star (ie, Deneb or Arcturus) -Onstep - Go To.
-Click Issue Align on the INDI control panel. This completes the alignment process.
-Right-click on the star near the meridian but at least 8mins away and issue a goto.
-Onstep goes to the correct location.
-Meridian flip setting in EKOS is set to 0.2 degrees. I can see the countdown timer.
-Then I wait for the star to cross meridian plus 0.2 deg and EKOS issues a slew but most of the time, it issues a slew to the last star I used for alignment (ie Deneb or Arcturus).

The coordinates shown in EKOS and Onstep are the same so not sure why EKOS. Not sure what I am doing wrong.

For reference, I have MaxPCB2 with Teensy 3.6 and TMC5160. I am using Kstars 3.5.4 Build: 2021-07-15T21:15:09Z and INDI driver version 1.9.1
2 years 7 months ago #74769

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Could you please turn on logging and try to reproduce it? I tried to follow your description with simulators, but there everything went as expected.
2 years 7 months ago #74786

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I'll reproduce it and attach the logs sometime this week. 
2 years 7 months ago #74789

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I think what's happening is that you're not setting the target in Ekos before you slew.  If all you do is right click the star before you lx200->goto , then  Ekos hasn't yet set the target.  Try doing "center and track" after selecting the star to ensure its set as the current target,  and then do the goto, and see if that works..
2 years 7 months ago #74791

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But If I right click on a target on KStars, then select lx200 -> goto, and then perform a plate solve, it works flawlessly, so it seems to me that this is not the case, isn't it?
2 years 7 months ago #74794

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Going to guess the alignment module has different approach.   Did you try setting a target first then doing the goto?
2 years 7 months ago #74824

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I did try that but it still slewed to the last star I slewed to. I did see the target under Setup page in EKOS change to M3 when I completed the following: Clicked M3 -> Center, and Track then LX200 Onstep -> GoTo. But the meridian flip went to the last star I slew to..

I am gathering the logs requested by Wolfgang . Should have it uploaded later today.

Note that the only workaround I've found so far is to slew to my target of interest twice and when I do that, I do get meridian flip to happen correctly.
2 years 7 months ago #74826

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Log files attached.
2 years 7 months ago #74827
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It seems like our mount reports the old position after the second slew:
[2021-08-23T19:09:29.160 PDT INFO ][           org.kde.kstars.indi] - LX200 OnStep :  "[INFO] Slewing to RA: 16:15:29 - DEC: 33:48:33 "
...
[2021-08-23T19:09:30.526 PDT DEBG ][     org.kde.kstars.ekos.mount] - Mount status changed from  "Slewing"  to  "Tracking"
...
[2021-08-23T19:09:30.681 PDT DEBG ][           org.kde.kstars.indi] - LX200 OnStep : "[SCOPE] CMD <:GR#> "
[2021-08-23T19:09:30.681 PDT DEBG ][           org.kde.kstars.indi] - LX200 OnStep : "[SCOPE] RES <18:33:39> "
You can see that OnStep reports 18:33:39 as current RA position and not 16:15:29, which is strange. Therefore it's not surprising that the mount uses 18:33:39 as current position for the meridian flip.

Conclusion: hm, either you are doing something unusual or this is simply a OnStep bug.
The following user(s) said Thank You: Jasem Mutlaq
2 years 7 months ago #74828

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Thanks for checking it out. I might be doing something odd or did something odd at some poing. I am new to both Onstep and EKOS.

I'll reset the Onstep firmware and see if it resolves the issue.
2 years 7 months ago #74842

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Hello all ...

This bug may be related to an issue that is inside Ekos (not INDI), that causes status changes to be immediate, and not reflect what is actually going on.

The above log seems to confirm that: it changed from slewing to tracking in merely one second.

This issue was discussed in this thread . I do not recall a definitive resolution yet.

One poster on the OnStep group identified where the issue is, but does not have a solution yet.
 
2 years 7 months ago #74848

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Could someone please check the status of the INDI property EQUATORIAL_EOD_COORD is always IPS_BUSY when the mount slews?

Here the explanation how Ekos recognizes the mount's tracking and slewing states:

There is one thread running that regularly reads the data of the INDI driver showing the current RA/DEC coordinates and its status. Simplified, IPS_IDLE --> mount is idle, IPS_OK --> tracking, IPS_BUSY --> slewing.

Now the question is how should we detect from EKOS that a slew is finished. Currently, we detect this that after a slew command, the mount shows the tracking state - and this is recognized by the thread above. When a slew is issued, Ekos sets the mount state to "slewing".

The problem occurs when the above mentioned thread reads the mount in parallel and obtains the tracking state BEFORE the INDI driver starts slewing. As a result, Ekos assumes that the slew has already finished while it hasn't even started.

But in this case, the time difference in the log is more than a second - that's why I think we do not have this problem here.

That's why I would like to check whether the OnStep INDI driver properly reports it's state
2 years 7 months ago #74854

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