Pulsar dome and POTH...Help!!!!

[Hallingskies]

I’ve been running my NEQ6 mount under EQASCOM quite happily for the past year or so, but have now decided to try and get my Pulsar Dome synched to the mount – but so far without success…

I have used Chris Marriot’s SkyMap Pro as my planetarium software for about 15 years and its ASCOM plug-in has worked well for NEQ6 go-to pointing.  But I’ve had no luck whatsoever in getting the dome to respond under ASCOM.  All the drivers seem to be correctly installed and there are no USB issues, with both mount and dome recognised in my Windows 7 device manager.

These are the steps I have used to attempt dome and mount synching:

Turn on computer

Power up dome

Power up mount

Open SkyMap Pro

Select “telescope”

Select “configure”

Select “ASCOM driver”

Select “POTH hub”

Select “Properties”

Select “POTH Set-up”

The big black ASCOM POTH screen comes up, with the “Scope Connection” and “Dome Connection” boxes.  I filled in the mount geometry information, then hit “Choose Dome”.

I selected “ASCOM Dome Driver for Pulsar Observatories” and hit OK.  At this point, the “Connect” button changes to “Disconnect” – so I assume the dome has connected.

The fun starts when I try to connect the mount.  From the “Choose scope” POTH set-up screen, I assumed I would need the “POTH” option.  When I do that though, I get a snarky little error message that says “Yeah right…try again”! (OK, clever clogs, any suggestions?  Thought not…).

So I select the “EQ5/6” option and hit “connect”.  The red and black mount info screen pops up, but closes again when I close the POTH screen (I can’t minimise it or bring anything up over it).

This leaves the SkyMap Pro screen up.  Right clicking on a star and selecting the “Synch To…” option points the mount and telescope as usual. 

But the dome, it moveth not.

I’ve tried various options, some of which bring up another mystery error message “Tracking in wrong state”, when I try go-to pointing (although the mount can be moved from the ASCOM mount N/S/E/W screen).

I assume the mount needs to be connected to the POTH hub as well.

Can anyone tell me what I’m doing wrong? Is dome synching even possible in ASCOM without SGP or MaximDL as an intermediary?

Any clues for the clueless would be greatly appreciated…

[steppenwolf]

19 minutes ago, Hallingskies said:

I assume the mount needs to be connected to the POTH hub as well. 

Yes it does. POTH must remain open for either the mount or dome to operate correctly.

For now, you need to concentrate on getting your planetarium software to connect to your mount via POTH. Normally, this is very straightforward so I am unsure of the reason for the failure. Connecting via POTH is normally a simple matter of choosing the EQASCOM driver for your mount, in this case, the EQ6. Ignore the Pulsar dome for now, get that mount connected and if necessary, I will then be able to give you some pointers regarding the dome geometry.

[Hallingskies]

Steve: Thanks for the reply, I'll certainly keep trying wrt the mount.  But in the POTH set-up screen, when I try to select "POTH" as a scope control option, I just get the "yeah right" message.  In the POTH set-up screen, I have therefore selected "HEQ5/6" as a control option and go-to works fine.  I see from earlier posts that you have it all running in POTH with no problem.  I just wonder what your option selection sequence is for set-up?  

Maybe the issue is with the SkyMap Pro plug in? It has all worked fine for go-to when connected under the HEQ5/6 option.  I could try Carte Du Ciel I guess..

[steppenwolf]

1 hour ago, Hallingskies said:

 But in the POTH set-up screen, when I try to select "POTH" as a scope control option, I just get the "yeah right" message.  In the POTH set-up screen, I have therefore selected "HEQ5/6" as a control option and go-to works fine.

OK, you are forming an incorrect loop here. To connect your telescope to SkyMap (or Cartes du Ciel), you select POTH as the telescope then click on 'Properties'. Here, you MUST click on the 'Choose Scope' button but do NOT choose POTH as this will give you a loop - instead, choose EQMOD ASCOM HEQ5/EQ6 (or whatever the latest EQ6 EQASCOM driver is called).

Hope that makes sense.

[Hallingskies]

Ok, will give it a try again.  Thanks.  

Plan B is just to make a graph by plotting the dome slot angle to a range of alt/az mount positions, then just use the Pulsar control software to “nudge” the dome if it gets on far from the plotted position.  

Plan C is to stick a webcam on the scope and watch the dome slot, nudging again via the software.

Plan D is to give up.  That looks the favourite, actually...

[steppenwolf]

Plan A is the correct course.

Plan B sound like a real pain when the system WILL work well when correctly set up

Plan C would take away the magic of automation

Plan D is not an option I'd recommend or it has all been for nothing

[Hallingskies]

7 hours ago, steppenwolf said:

...or it has all been for nothing

Well, the object of the exercise for me is to run things unattended, rather than go fully remote.  Unfortunately I’m no wizard when it comes to the “magic of automation” , but I am pleasantly surprised to have been able to get mount pointing, CCD, filter wheel, guiding and focusing all working from my obbo PC so far.  I’m sure the dome synch just a matter of settings, but one way or another, it won’t be for nothing.  One missing bit of the jigsaw doesn’t make the whole thing pointless! I will keep playing with it in the daylight - at least now I know there is one person (you) who has made it all work!

[skybadger]

It works for me too , for years. Worst thing is a Dickie dome driver.

Mine worked with skymap too until I thought it was discontinued, now I use CdC.

 

[Hallingskies]

...OK, two people...?.  Skymap is still going (v12, I think) but I guess the freebies have kind of superseded it.  It’s certainly more intuitive than CdC and doesn’t eat RAM like Stellarium, but I’ve been using it for about 15 years mostly because I tend to stick with what I know, if I can...

[steppenwolf]

Keep us posted as between us we CAN get this working for you. Daytime setup of this feature is a great advantage - no dark, clear skies are required for this aspect of remote operation.

[Hallingskies]

Ok, had another play yesterday evening.  Got the mount pointing going just fine from my planetarium software using the EQ6 ASCOM driver via POTH, as you suggested.  With the Pulsar dome software open and the dome operable, attempts to connect the dome via POTH threw up an error message “COM port 5 unavailable” (having already selected the Pulsar ASCOM dome driver, I entered the COM port manually in the POTH set-up as the trace didn’t seem to pick it up).  I checked the device driver folder and the dome shows up under port 5, and I know it’s not a USB issue as I can move it via the Pulsar software.  Closing the Pulsar software allows me to apparently connect (the POTH screen tab changes from “connect” to “disconnect”) but the dome stays put (presumably because it needs the Pulsar dome control software to talk to?).   Seems like a COMs port conflict in ASCOM - or a dome driver issue?  I have installed the latest dome driver from Pulsar and it comes up in POTH as a control option, so I assume POTH is seeing it.

It’s always aggravating when the last bit of the jigsaw is missing....?

[steppenwolf]

3 minutes ago, Hallingskies said:

Closing the Pulsar software allows me to apparently connect (the POTH screen tab changes from “connect” to “disconnect”) but the dome stays put (presumably because it needs the Pulsar dome control software to talk to?).  

The Pulsar Software must NOT be running when you use any ASCOM control for the dome - the two are mutually exclusive. All you need to do now ('All' he says!) is to start the whole PC from a reboot, do not run the Pulsar software, route through to POTH and select the Pulsar ASCOM driver - you should now not have that COM issue as only one piece of driver software is trying to connect to the COM port.

[Hallingskies]

Another day, another play....and success!!  Well, sort of....  It does seem that you need to connect stuff in a precise order to get it all to work.

Anyway, I got the big black POTH set-up screen up, but I didn't try to connect scope or dome from this screen.  Instead I decided to just click OK and close it because all of the settings seemed correct.   I then went to "Open connection" from my planetarium software (SkyMap Pro) and this brought up a little black POTH screen I hadn't seen before.  After trial and error, I worked out that, once connected, I had to tick the "track" option on the POTH scope side to get the goto to work from SkyMap (at first I kept getting a "wrong tracking state" error message when I tried a go-to from SkyMap).  Ticking "slave dome" on the dome side then got the dome to move with the scope!  At last!  The dome gap was almost following in the right place relative to the scope, but then I made the mistake of putting the dome park angle in the blank box and hitting the "synch" button on the POTH screen dome options.  This sent the dome flying off course and seems to have completely messed up the dome calibration.  I left that to re-do tomorrow, which I will do stand-alone from the dome motor control panel.  

So now I need to know what that "synch" option does in the POTH connection screen.  What is it "synching" to, and what number do I need to put in the blank box?  Should I calibrate the dome to a "home/park" position of 0 degrees so it doesn't have to rotate to catch up with the mount in "park" position?

Should I have "synched" to the park position before I ticked the "slave dome" box?

Any answers appreciated - assuming this garbled account makes any sense to anybody....

[steppenwolf]

Well that sounds more encouraging!

You don't need to put ANY numbers in the Synch. box, however, you do need to put a Home and Park angle in the Pulsar software BUT NOT while connected to POTH or you will be back in problems again! A recommended position for the Northern Hemisphere is to set the Home and Park positions to 180 degrees so that the solar panel (assuming that you don't have the induction charger) is pointing due south when the dome isn't in use.

[Hallingskies]

OK Steve, thanks.  

I don't have a motorised shutter and associated solar panel so the position of the dome when parked is of no consequence.  At the moment I'm just looking to be able to remotely monitor an imaging session (and do filter wheel changes and refocusing) rather than fully automate it. 

[steppenwolf]

In that case, just chose a position that generally suits you but 180 degrees also places the aperture pointing south and for me, the majority of my imaging is in that direction as my house is north of the observatory so it would make sense for you to have the opposite side to the shutter pointing at your least observed portion of the sky. You would then leave the dome parked but slew the telescope to your chosen celestial object then tick 'Slave Dome' and it will have the least amount of distance to travel.

[skybadger]

My experience of this is to:

1, open the planetarium software

2, choose to connect to scope

3, select POTH as the scope, select configure and select your scope and dome drivers. Configure the dome offset parameters. OK to close.

4, if your planetarium supports a dome device, click to configure, select POTH, click OK as it is already configured.

5, In your planetarium , click connect. 

POTH dome and scope window should open. Sync to scope should already be selected and your dome should now be tracking the scope. 

However I've only seen Maxim  be intelligent enough to wait for a slew to complete before moving the dome, otherwise the dome goes off on a merry dance, tracking the scope.

The POTH sync box is to update POTH with an offset to use if the positional readings have a constant error. 

HTh

 

[Hallingskies]

Thanks everyone.  It’s all starting to make sense, will reset dome calibration this evening and see how I get on.  Thanks again.

Will also have a go at a meridian flip.  I initiate this manually, so presumably I could free the dome, do the scope flip and then slave the dome again, to save it spinning with the telescope.  Be interesting to see what happens.

[skybadger]

Is there a season you initiate it manually rather than letting the scope do it's thing and letting the dome work herself out ?

 

[Hallingskies]

No, it’s not seasonal, I initiate flips manually at any time of the year...?

If I let it “do its own thing” than an auto flip will always take place during the last ten seconds of a long sub, and then once complete, the target will need reframing.

My way, I just interrupt a sequence at the end of a sub once I see the target is a fair  way past the meridian, but not on the mount limit, and can then flip and reframe quickly and restart the sequence.  It cuts down on wasted subs and makes sure I can still stack pre- and post- flip subs together.

[Hallingskies]

Thanks to those who have replied and encouraged me to stick at this.  At least I can now get the dome to follow the scope, albeit about 30 degrees out.  I’m sure this is just a question of playing with the dimension details in the POTH set up screen.  I have some other equipment issues to sort out, but I think the dome problem is now solvable.   

Another problem solved (almost) by the combined brains of SGL.....?

[Hallingskies]

Just out of interest, does anybody know the details of the calculation that must be tucked away in the POTH software, and that works out the orientation of the dome based on the position and dimensions of the equatorial mount under it?  

I had a go at working it out myself but I’ve forgotten my A-level maths and it’s been decades since I calculated the arcsine of anything.  Had a quick dig on the interweb but have drawn a blank.

[steppenwolf]

On 09/08/2018 at 10:31, Hallingskies said:

Just out of interest, does anybody know the details of the calculation that must be tucked away in the POTH software, and that works out the orientation of the dome based on the position and dimensions of the equatorial mount under it?  

Here you go - it's quite simple actually

Document 1   and

....... Dome Slit Calculation

[Hallingskies]

Steve:

Once again, many thanks.  I wouldn’t have called it “simple” but at least I can work some numbers out if I need a plan B.

[steppenwolf]

3 hours ago, Hallingskies said:

I wouldn’t have called it “simple” but at least I can work some numbers out if I need a plan B.

'Twas a little tongue in cheek to be honest - never lose sight of the fact that calculus is still a mystery to me as I never could understand why you would ever need to know the area under a graph plot .....?