Solved! Dome Alignment parameter signs - The SkyX vs MaximDL

[g__day]

Hey folks,

I have purchased TSX and tried to get the Dome Automation and sycnhronisation working from within the SkyX PE as well as it did between the Sky6 and MaximDL v5.

So basically I took all the measurements in inches and multiple them by 100 to avoid fractions but keep all the ratios consistent.

Dome Radius MaximDL 44.9" - vs - The SkyX Dome Radius = 4490
Dist Dome Centre to Mount Pivot (East / West) -4.25" - vs The SkyX Xm = -425 (tried +ve/-ve)
Dist Dome Centre ot Mount Pivot Pt (North / South) -8.25" - vs - The SkyX Ym = -825 (tried +ve/-ve)
Mount Pivot point hiegth to Dome Eq -26.5" (Mount below Dome Axis) - vs - The SkyX Zm = -2650
Distance of Mount Pivot Point to Scope Optical Axis 13.25" vs The SkyX Xt = 1325 (tried +ve and -ve)


The alignment is a fair bit over the place in TSX and perfect in Sky6 / MaximDL. Any idea of which geometry parameter/s needs their signed flipped for the Southern Hemisphere.

* * * * * * Solution for lazy people who don't wish to read on :)



Connect to the SkySensor2000-PC as a Meade -> LX200 10" f/10 driver
Under Display this adds an item right down the boot under Video called Meade - click on this
Select the first tickbox labeled German Equatorial Mount and set this On!
Check the sign of your Xt parameter - mine needed to be positive


And that's all it took. Once TSX realises it handling a GE mount it adds or subtracts Xt properly depending on which side of the Meridan your mount is positioned at!

Thanks to Dan Bisque at Software Bisque for that reveal!

[g__day]

If any folk have got the SkyX with dome working for MaxDome II I would love to hear what you did and if you know the signs for parameters in our Hemisphere!

I just tried it all again - using mm for all measurement, and tried swapping signs +/- in case documentation is wrong. Still no joy - occassionally the dome slot in the SkyX even shows the scope isn't inside the dome position - don't know why that ever occurs!

All the slews were immediate - they just ended up in the wrong position nearly every time. When I switched the dome connection off in the SkyX and simply slewed the scope using MaximDL to slave the dome to a SkyX controlled OTA - all dome slews were once again perfect - aggravating - as I am trying to get entirely onto the SkyX and I guess the geometry positions are all still askew for my Hemisphere.


So Location is set to Sydney Australia - at my local GPS H M S according to Google Maps for my house and Time looks right - from my PC's internet updated clock. Home position is the park position = 119 degrees.


For all slews the Dome's reported position was absolutely correct - I have all bearings on the compass in 10 degree increments noted around the base of my Dome.


Offsets are now entered:
Xm = +108 (Mount Pivot point East of Dome centre 4,25")
Ym = -216 (Mount Pivot point South of Dome centre by 8.5")
Radius = 1140 (44.9")
Xt = -330 (Scope mounted on top of Mount pivot point so optical axis is 13.25" above the pivot point)
Zm = -673 (Mount pivot point 26.5" below dome centre of rotation
Slot = 610 (Dome slot is 24" wide)
Angle from Slot to OTA set to 5.00 degrees.


So from my data (using mm rather than inches now) are the signs right on these variable for my hemisphere?


What's the next thing to try given in cases TSX complete a slew but shows the Dome is left of the OTA? Is there a testing methodology to optimise how to find the trouble?


I will be estatic once the SkyX can control the dome as well as the Sky6 + MaximDL can!

[g__day]

So I just checked all my measurements again - found one stupid mistakeI had translated 13.25" for Xt into 370 rather than 337mm - doh moment.


Once I fixed this Dome to OTA pointing improved in the Easter side of the mount and I noticed very strange behaviour.


When pointing East of the Meridan - and multiple elevations in 30 degree incremnts to the SCP pointing was almost spot on so long as Xt was -ve.
When pointing West of the meridan dome to OTA alignment was very good at all elevations provided Xt was +ve.
When pointing close to the SCP the software seemed to miss the meridan flip.

When I reverted back to MaximDL aligning the dome to OTA - all alignments - both side of the meridan close to the SCP or due North - where all spot on.
Does this help identify the problem? Why should pointing East or West of the Meridan require the sign of Xt to flip? Is the fact I am not using a native Vixen SkySensor2000-PC driver but instead a generic Meade LX200 driver confusing meridan switches for the SkyX or its Dome management software?


So Current parameters are:


Dome Radius 44.9 MaximDL, 1150 The SkyX
East West offset -4.25 MaximDL, -108 Xm The SkyX
North South Offset -8.5 MaximDL, -217 Ym The SkyX
OTA to Mount pivot offset 13.25 MaximDL, needed +337 Xt in SkyX when scope West of Meridan and -337 Xt when Scope East of Meridan
Mount distance below Dome -26.5 in MaximDL and -673 in the SKyX.

Hope this helps define the issue better guys!

*** Chris Rowlands just commented on the Bisque forums that the LX200 driver doesn't know about Meridan side - so it will be interesting to see how The Bisque brothers step up to resolve this.

[marc4darkskies]

Hi Matthew,

I'm one of those people who has never had a problem with dome tracking - with two mounts and two telescopes using TS6 and TSX. Frankly, this doesn't actually qualify me to help others resolve problems - I've tried and failed in the past!!

Apologies if you've already checked this stuff but:


Make sure your ticks per revolution is correct. Mine is 227 from memory but you should auto calibrate.
Make sure your home position is accurate. Home then do a dome rotation (using TSX or ASCOM dome control without the mount connected) to the cardinal points to make sure all is well. Home before every test.
Ignore the dome slit rendering against the sky in TSX. It is accurate but the location of the slit is wholly dependant on the geometry and is not what you see when looking along the optical axis of the scope. I'm not sure what the reference point is but it may be what you see when you look through the slit from the mount pivot point.

Of course you shouldn't have to reverse the sign of Xt - that makes no sense at all and tells me it's some other parameter that's wrong.

Cheers,
Marcus

[g__day]

Marcus,

Thanks for your suggestions. Point one already done - agrees totally with yours 227 after two auto calibrates to be sure of consistency.

Point 2 - The Home and park are set to 119 - and I would say are accurate to within a degree. When TSX solves the dome required position and sends it anywhere - say 158 Az - from my markings around the dome lands exactly where it is meant to - within say 10 mm or better - checked this every 10 degrees from 0 to 360!

The alignment misses are only in TSX controlling things and only after a meridan flip where it will be generall around 10 - 15 inches out when close to the horizon; very close to the SCP its about 26 inches - with the DEC arm parallel to the ground - which I infer means it definitely missed the meridan flip!

I might posit your Paramounts have well written drivers that correctly pass on side of Meridan to the SkyX. You'd be pretty upset if $20K of mount and software couldn't understand a Meridan flip wouldn't you!

Software Bisque wrote the ASCOM X2 driver - but for some reason it doesn't support the Vixen SkySensor200-PC ASCOM driver - when you try to connect the software just times out.

I might try it with TSX -> Maxpoint -> SS2K and see if it can connect indirectly through the Maxpoint hub and what its behaviour is around Meridan flips.

Regardless, when it connects to a generic LX200 mount the SS2K can emulate this and point fine - however TSX misses the Meridan flip whilst it appears MaximDL realises that it has happened and accounts for it in the Dome Solve correctly.

So to me the reversal of the Xt parameter alone fixing everything tells me geometry is absolutely correct however algorith is incorrect or relies on a Driver parameter that isn't being set correctly - the TSX perhaps just reads this side of Meridan parameters whilst MaximDL calculates it! The guys who responded to my issue (Chris Rowlands - I believe has written a driver or two so likely knows wat he is talking about).

Matthew

[g__day]

Hmmm,

Not quite what I expected - I used Maxpoint -> Vixen SkySensor2000-PC to control the mount and simply told both TSX and MaximDL to use MaxPoint to control the mount (as Maxpoint is a hub).

Pointing was fine - however same behaviours unchanged from TSX - only one side of Meridan correct depending on which sign Xt is given and MaximDL gets it right every time with no parameter adjustment. I wasn't quite expecting that.

So I guess it tells us MaximDL is doing something helpful, and a bit different, to TSX.

[g__day]

Solved thanks to Dan Bisque, will share the fix here in case anyone else encounters this.



When you control the SS2K-PC as a Meade LX200 emulated mount you must also go to the Display tab and right down the bottom a Meade Tab will appear. When you select this a screen will appear and it gives you the Option to select a Tick box saying German Equatorial Mount - that easy!



Once I had done this - and then set the sign of Xt back to +ve it all worked exactly as one would hope - whether TSX slewed the scope or I did using the controller - on either side of the Meridan the Dome and Mount align very, very well!



Gald when the testing methodology and querying forums works that well!



Cheers, Matthew