SGP and SkyX not communicating well

I have been using SGP, PHD2 and SkyX to control Paramount MyT for about a year and everything worked well until I decided to set up a NUC (windows 10) on top of the telescope to control everything remotely. After a fair bit of effort, most things are working but suck on Auto Center in SGP. Plate solve works fine but sometimes gets stuck on “Slew to Reference Frame” and I have to close SGP and restart the program to try again. When SGP does move on to the “Validate” step and target is off by greater than 50px, the Auto Center sequence will keep running but I’ll never get any closer to the target. In other words, if attempt number one is off by 200px then attempts 2 and 3 are off by the same number of px.

I have also noticed that the “Plate Solve and Sync to Camera Frame” step will not work at all (message says failed) unless I check the box for “Inhibit Sync to Protect TPOINT” int the ascom driver for the Sky. PHD2 also will not connect to the ascom driver for the Sky unless this box is checked. I never had to check this box in the past. Needless to say, I am not able to center a target in SGP or perform an automated meridian flip but had not trouble in the past. Am I missing a setting somewhere? Anyone with similar problems?

Using SGP v and made sure SkyX and PHD2 are up to date.

You need to post your log files.


Meridian flip attempt starts at 12:18. I noticed that there is an error message at 12:24 failing to convert J2000 to JNOW. Could that be the problem?

Here is another log in which Auto Center failed prior to meridian flip. Starts around 9:57.

For whatever reason, TSX does not like the sync command:

[8/18/2016 9:58:05 PM] [DEBUG] [Telescope Thread] Telescope: Syncing to J2000 RA: 20.8549636647307 Dec: 44.3344147882599
[8/18/2016 9:58:05 PM] [DEBUG] [Telescope Thread] Telescope: Telescope does not support sync, not syncing.

No sync means no center function. Maybe there is a Setting in TSX to activate this.


In the TSX ASCOM driver, uncheck the box to inhibit sync. Then the sync command will go through and the mount will center as usual. My MX+ does the same thing. I don’t know why but if sync is inhibited, SGP will never get the target centered. Also, don’t use the daily builds of TSX. They don’t work with SGP at all, it won’t center at all whether or not sync is inhibited.

For PHD2 to work, check off “enable tracking offsets” and “use DirectGuide” and “can get Pointing state”. Also, I have had to use POTH between SGP, PHD2 and the TSX ASCOM driver. TSX doesn’t seem to pass lat/long coordinates back to the other software which prevents some from slewing correctly. POTH has fields to manually enter your location coordinates.

Maybe this will help?


Thanks, very helpful suggestions. This is probably a dumb question but
what is “POTH”?

I’ll try getting rid of daily builds for TSX and double check settings for

Is there a way to drop the daily build or do I need to re install an
earlier version of TSX?


There are instructions on how to remove the daily build on the download page for the daily build. You just have to copy files back into the directory and it’s back on the release version. If you were trying to use a daily build, that was likely the problem. I can’t get SGP to center with those at all.

POTH is “Plain Old Telescope Handset”. It comes with the ASCOM downloads and will be a choice of mount driver in SGP or PHD2. It helps to interface problematic equipment, especially when drivers do not conform to the full ASCOM standard, which TSX does not. In POTH you then choose the ASCOM driver for TSX. If I didn’t use this, PHD2 could not slew the mount for drift alignment. It would still guide, but it couldn’t slew to a specific location because it did not get GPS coordinates from the TSX driver. If you don’t use the drift alignment tool to slew the mount you can have PHD2 connect directly to the TSX ASCOM driver.


The “daily builds” of TSX are unavoidable. In reality they are simply the latest version. If you ask about any problem on the SB forum the first thing you will be asked to do is install the latest released “daily build”.

Behind the scenes a daily build will be generated every day, probably overnight from the previous day’s checked in code, and the first line testers will be testing this. Most won’t see the light of day but when sufficient changes have accumulated a recent “daily build” will be released. It doesn’t happen every day and should take some time and - hopefully - additional testing before it is released.

POTH is an ASCOM hub that allows multiple applications to talk to the same telescope. It shouldn’t be needed because the SB ASCOM driver and TSX will do the same thing.

Chris R

I’m a bit confused. If daily builds are unavoidable and interfere with
SGP, what can be done to keep SGP and TSX working together?

I uninstalled TSX and re installed TSX Full Installer v10.3.0 build 8461
from the bisque website (daily is build10133). The UI is not quite as nice
but if works with SGP, I won’t care.

Looks like may have a chance to try tonight if clouds keep moving away.


Tried again last night. I tested auto center and meridian flip on a couple
random stars near the meridian. When I connected SGP and PHD2 via ascom
driver for the sky, the meridian flip failed (see 10:32:17 in log). I
then connected SGP and PHD2 to POTH and POTH to TSX via the ascom driver
for the sky. This time the meridian flip was successful (starts at
10:46:45 in log).

Feeling confident, started my sequence and went to bed. This am, looks
like the meridian flip (starts at 12:56:54) initially failed stating “Error
transforming J2000 to JNOW!” (1:02:42 in log). It then when into recovery
mode and meridian flip and auto center was successful.

However, PHD2 was never able to settle after the flip and the sequence was
aborted. The PHD2 graph was all over the place although there were clearly
guide stars available. Do I need to check “reverse dec output after
meridian flip” in the PHD2 settings when connecting through POTH? Is there
some other setting I’m forgetting about?

This is getting really frustrating. Many clear nights wasted trying to get
all of this to work. Any suggestions would be appreciated.


Hi Kwas,

For the paramount you do need to check “reverse dec output after
meridian flip”

No sure why you need to use POTH, for reference some screen shots of the setup I have, I use the current SGP release and the latest PHD2 release (dev version if available).

ASCOM setup

Flip Settings

SkyX version

The latest daily builds 10.5.x onward caused plate solve centring to mess up.Will look into this soon and try and figure out what the issue is, not looked on the SB forums so not sure if this had been reported. Like some of the new features in the latest SkyX so would be good to figure out what is wrong.

Meridian limits



You limits and time past meridian need to match, was caught out early on by not having wait for meridian ticked, taking 30min subs and a limit of only 20mins past and the next 30min sub started 5mins before meridian.

PHD Guiding TAB

Hopefully this may be of some help.



1 Like

The PHD2 User Manual describes how to determine whether or not you need to check the “reverse dec output after meridian flip” option. Here’s the link: Manual - PHD2 Guiding. Scroll down to Shared Guiding Parameters, Reverse Dec output after meridian flip.

Or, you can post your PHD2 Guide Log and we can answer your question by looking at that (“all over the place” is not specific enough information.)


Trevor, thanks for posting all your settings. It is very helpful to see
the actual setup.

Andy, appreciate the input on PHD2. I had been successfully using it for
over a year. While my paramount was being repaired, I started using my old
Atlas mount and fiddled with the PHD2 settings. I must have been mixed up
when I recently went back to the paramount.

I seem to be stuck in in an endless loop of problems but its great to have
people willing to offer help!


As a Paramount owner, I have strenuously avoided the “Daily Build” merry go round until they are finally released into a fully debugged TSX version. That can take a long time.

Currently, I’ve got the latest build of TSX on my desktop (only) where I can watch for bugs and it can do no harm. It will not see any action on my imaging PC for the foreseeable future.

Unfortunately it is true SB will instruct owners with any problems to upgrade or there will be little or no help forthcoming from them.

The other thing to remember is SB does not archive the Daily Builds. You can only revert to the last build stored in the TSX folder on your computer’s hard drive.

This is a problem for any SGP user that wants accurate centering. The newer builds of TSX don’t work at all with centering. They just won’t get closer. Large slews work but it will not move once the correction is only a small amount. The centering error doesn’t change after a certain point. I will go ahead and post a question with SB.

I use the POTH because without it, slewing of my MX+ won’t work with the PHD2 drift alignment tool. TSX ASCOM driver does not pass location coordinates to PHD2. PHD2 RA slewing uses degrees from meridian so it needs to know where you are. The POTH has a place to manually enter lat/long coordinates. Other functions of SGP and PHD2 work fine without POTH but I just leave it in there.


I posted in the Bisque TSX forum. The answer I got is that any sync functions have been removed for Paramounts. That effectively breaks the centering function of SGP with newer builds of TSX.


So, what is the future of using SGP with TSX? Will SGP developers be able
to work with SB to fix this issue?


Question for SGP:

How about an option to use SkyX image link and closed loop slew (which
works great) and avoid the need for SGP auto center?


Just seen that post, nothing in the daily build release notes about that being removed, also means the X2 Ascom drivers inhibit sync check box is redundant when using daily builds.

Maybe figuring out why SGPs plate solve requires a sync where ACP and CCDAP dont seem to, not used them so not sure if they use the Ascom driver.