FindHome() implementation issue in the OnStep ASCOM driver

buzz · November 23, 2024, 10:30am

I have an issue with the homing ASCOM implementation in OnStep.

The FindHome() method definition changed between V3 and V4 telescope implementation.
The V3 FindHome() method only returns when the mount has found home, whereas the latest V4 method call is asynchronous, returning immediately, and has to set the slewing property true whilst it is homing. When it is homed, AtHome is set true and slewing set false.

The OnStep ASCOM driver is returning immediately from a FindHome() method call, but it is not setting Slewing to True. This is causing confusion with imaging applications, which monitor slewing property and assume homing is complete before it has found the sensors.

The best solution is to have the driver set slewing=true while homing. One could return from FindHome() after finding home but it is not preferred as it is the old standard.

buzz · November 23, 2024, 5:36pm

Howard has released a change to the ASCOM driver. Until ASCOM 7 is more fully established, he will adopt the V3 standard, returning from the call when it has homed, or raising an exception after 4 mins if it hasn’t.

gustavo · November 24, 2024, 1:54pm

Does this resolve the issue of the scope not searching for home when slewing large distances?

buzz · November 24, 2024, 2:34pm

I have not explicitly tested, but assume not.

buzz · November 24, 2024, 3:27pm

Gustavo - I would also hold off the change (1.0.41). I was testing it earlier and it has a bug which causes it to report the guide rates = 0 , an illegal value, and causes PHD2 to fail. Hopefully another one tomorrow.

buzz · November 25, 2024, 8:38pm

10.0.42 has been released - it should fix both the FindHome anomaly in 10.0.40 and the GuideRate one too, introduced in 10.0.41.
Gustavo - for homing, I developed a simple script that replaces a home and park instruction sequence in NINA. It homes twice - so it should overcome slews of over 90 degrees. Let me check out the new ASCOM driver and I can share if you want it. (You could also do this in NINA, too;

unpark
tracking on
delay 5s
home
tracking on
delay 5s
home
tracking on
delay 5s
park

best
Chris

buzz · November 27, 2024, 5:41pm

ASCOM 1.0.42 has been released, making it unnecessary for workarounds in NINA. This version returns from FindHome() when it is complete and reports the guide rates correctly for apps like PHD2 to use.

gustavo · December 18, 2024, 2:24am

I just saw this… been a busy couple of weeks. Did you have any issue updating?

buzz · December 18, 2024, 6:46am

None at all. ASCOM drivers uninstall their old version automatically. I have moved most of my posts to the discord forum. I have been busy too, writing a user manual. Not finished yet but making progress. Here is a link

gustavo · December 18, 2024, 1:57pm

Welp… unfortunately I apparently like to break from the norm. Now it wont detect the telescope at all.

buzz · December 18, 2024, 5:33pm

that is for the onstep focuser - part of the Onstep system but not for this mount
How did you get here?!!

You can always uninstall the driver in windows settings and start again.

gustavo · December 22, 2024, 4:45pm

The OnStep Ascom driver install installs it as part of the driver “suite” during the process.

Yeah, I uninstalled it but the issue was that it wasn’t deleting the OnStep do user file (the DLL).
I had to go to the install folder, manually delete everything in the onstep folder and then the install completed successfully, no errors.

Btw, this did not fix the “no seek after long slew issue to home”

It still misses and stops but I can deal with it.

Got this a couple of nights ago - guiding was shit, but so was the seeing, sooo… it wasn’t so bad.

gustavo · December 22, 2024, 4:48pm

That was under B7 skies and a 91% moon.

I had to recalibrate guiding a few times during the shoot.

You can see me recalibrate in the video

Also in the video, after the meridian flip (1 minute in), the scope wouldn’t track. I had to reset the entire thing. I was worried it hit the limit, but it worked fine after I went to home and slewed to target again. I lost about 30-40 minutes of prime imaging time, but oh well.