My Mount Needs A Good Talking To

[gnomus]

When imaging I control my mount via the PC in my warm room.  Most of the time, this works superbly well.  Every now and again, however, I encounter some strange behaviour.  This is, I know, entirely down to me, but without knowing how the software is ‘talking’ to the mount it is difficult for me to know how to fix it.

I have a Celestron CGEM mount.  Prior to the computerisation I would have to start it up and go through a two-star alignment procedure, followed by a further three-star calibration procedure (if I wanted GOTO accuracy).  This worked very well.

The software that I use most frequently is Sequence Generator Pro (SGP), PHD and Cartes du Ciel (CdC).  The plate solving and centring of objects in SGP very nearly made me cry with joy when I first got it working.  (I still let out a little whimper every time it works).  However, I cannot use SGP on its own.  I have to use CdC to slew to a bright star for focussing (if that star is  off a bit, I can centre the star and ‘Sync’ the scope in CdC).  Then I slew to and centre on my chosen target with SGP.  Again, normally this works, but it is here that I occasionally run into trouble.  Last night, for example, I tried to slew to Dubhe (for focussing) and the scope ended up pointing in completely the wrong direction.  Once I had this fixed, my attempt to return to the target (Elephant Trunk) had the scope going off in a bizarre direction – I had to power down the mount quickly to stop my camera striking the pier.

I assume that the mount is in some way becoming ‘confused’ by having two programs (three when PHD is running) trying to control it.   

The other issue is ‘Parking’.  My handset offers me the option of “Hibernating” the mount.  SGP offers me the option to set a Park position and then Parking and Unparking the mount.  Sometimes, parking and unparking in SGP works.  The majority of the time it does not.  When it works there is always a few seconds delay between sending the Park command and the mount actually moving to the set position.  I have just made some changes to my set up such that I will need to get a Park position that is different from the CGEM’s Home position (otherwise the roof is going to strike).

My question, therefore, is: is there a correct way of co-ordinating all of this better than I am at present?  Am I supposed to Park the scope using SGP and then Hibernate it using my handset? Why does Parking via SGP not work every time?  Should I ignore Hibernating the mount with the handset if I am Parking it with SGP? On start-up, should I simply power the mount up and select “Last Alignment” from the options?  (Just switching the mount on and ignoring all of the handset messages does not work since CdC tells me that the mount needs to be aligned (maybe it says ‘Synced’) before it will slew.)  Is it OK to have both CdC and SGP talking to the mount? Should I start these programs and connect them to the mount in a specific order? Should I disconnect one program from the mount before connecting to it with the other?

I am on the verge of having the system running really smoothly.  We are very fortunate that things are so easy these days.  I would still like to get it all running as optimally as I can though.

Any thoughts on these ramblings would be much appreciated. 

   

[Davey-T]

Can't be any help but sympathise, my set up works nine times out of ten then one night I fire it up and get "camera not found/can't connect" messages or PHD refuses to calibrate, of course next day it all works 

Dave

[gnomus]

Yes. Last night's effort was brought to a premature close by PHD issues. If only I had the dough for one of those GM 2000s.

[Zakalwe]

I doubt if the problem is caused by two or more programs connecting to the mount at the same time. The ASCOM standard is designed to allow just that. For example, the other night I had 3 planetarium programs connected to my mount and all were being updated over ASCOM when the mount slewed (CdC, SiTech's Skyview and Stellarium over Stellariumscope). The more likely culprit is that the first or subsequent align were incorrect or had become corrupted. This is where SGP's plate solving is so good.....just point at any are of the sky and let it do a blind solve and sync. The solve and centre routine is even better.

[gnomus]

You are right about the blind solve. It is reassuring that I can run multiple programs. What do you think about the order of firing up the hardware and software?