WD-20 Slew accuracy with NINA and returning home

[gustavo]

Hi there! We’ve spoken over chat and email but wanted to get this conversation on the forum in case someone else is experiencing the issue or resolved it on their own.

I have the WD-20 with the Takahashi FSQ-106 on it (and the PrimaLuce Eagle on that as the controller). I noticed that when using NINA to slew to home, it will overshoot on the RA by about 3-5 degrees (and it will not correct it’s position. Then, if I slew back to Zenith, I will be off the RA by that exact same distance.

Steps to reproduce:

1. Use NINA
2. Open Flat Wizard
3. Slew to Zenith
4. Open Equipment > Mount
5. Slew back to Home

However, if I slew to Zenith and then long-press the physical home button on the mount, it will slew back to home, overshoot the RA by the same amount, then slowly correct back to actual home.

I’ve tried adjusting the slew rate and making it slower (was at 10d/s and brought down to 6), this did not help.

Video slewing home from Zenith with NINA

Video slewing back to Zenith from NINA (after the overshoot), then back to home using the physical button

I also just tried using the hand controller and it exhibited the same behavior as from NINA. I have to tell it to go home twice from the HC to get it to do the correct adjustment and centering.

[buzz]

Very similar setup with the Eagle - I have only just got this mount and the Eagle, so working through it slowly. I have seen inaccurate homing, where it does not hover around, finding the position.

It is raining now, but I will double check it with Nina and my simple mount controller app, which uses plain ASCOM commands. I have not noticed since updating the firmware this week, but I have not been looking that hard either. I have been figuring how best to move off Park and Home positions. I have noticed that Homing gets confused, says it is homed when it is clearly and old status, but turning tracking on and homing again does the trick.

[gustavo]

I actually don’t think it has anything to do with NINA / Eagle anymore since I can reproduce the behavior with the hand controller.

Use NINA to easily slew to zenith (or make that your park setting), then use the hand controller to slew back to home.

If I slew back to home a second time, only then will it search to find the correct position (which is similar to enabling tracking and then hitting home again).

[buzz]

Makes sense. Are you using the recent firmware update?

In Nina sequences, I’m guessing you can, powering up from park, unpark, tracking on and then home. Fix and forget

[gustavo]

Yep, that was a whole different experience. Apparently I got an older serial number.
But yeah, I’m running 20.21

[gustavo]

** EDIT **
After messing around with EC Guard settings and disabling it, it had no change.
I did notice that slewing to home is fine if within a certain distance, but outside that distance (I don’t know what the breakpoint is), it fails to seek home correctly.

After reading the details regarding the firmware update, I wonder if this is the source of the slew issues:

WD-20 20.21W Firmware Upgrading Available - Introducing New Safety Features

New Safety Feature - Encoder based HA Limit(EC Guard) Category: Safety & Limits Function Introduction Encoder based HA Limit(called as “EC Guard”) designed to monitoring motion of RA axis during tracking/slewing/guiding. It’s a adjustable limit that stop the motion of mount once limit reached. Advantages Different from other most frequently used software limits in mount. Traditional software limits rely on correct coordinates system of mount. While coordinates could be wrong set/synced duri…

The EC Guard

[Technical]

Hi,
From your video posted, it seems that mount can slewing back to home precisely with home button pressed, while failed with home command from NINA.
It supposed to be issued with NINA, as another user also reported it back to normal after re-create NINA profiles. Refer to comment below:

Happy to report all my issues are sorted and were related to Nina freaking out. I think the sudden chnage in parameters for the mount upset Nina and maybe something was cached somewhere. I deleted my Profile in Nina and recreated from scratch and everything is working perfectly including the homing and 3-point polar alignment that i was having issues with, so happy days

Please try below possible available solution based other user’s practice:

• Unpark the mount and reset park position of mount again. In case any cache stored by NINA, that it actual not sending home command properly.
• Re create NINA profiles, in case any old speed and other cache cause issue

This issue should not related with EC Guard and AEB. It seems NINA stored old slewing rate and other cache that possibly caused the issue after firmware upgrading, as slewing rate improved in new firmware.

If the issue still existed, please contact our support via ticket or discord online, to perform a factory reset.

Regards.
WarpAstron Support

[buzz]

I think this is a more widespread issue and maybe ASCOM or driver related. The following is 100% repeatable.

USING NINA
Park (to Alt/Az 1,1)
Unpark (in NINA )
Immediately HOME (in NINA)
… Mount overshoots home position and does not come back.

Putting in a delay makes it always work:
Now Park again
Unpark (in NINA)
wait 5 seconds
Home (in NINA)

… mount homes correctly

The exact same behaviour happens using simple ASCOM commands in a Windows Form app (that I wrote)

my app:

private void park_mount(object sender, EventArgs e)
{
try
{
if (mount.CanPark && mountconnected)
{
if (!mount.AtPark)
{
statusbox.Text = “parking”;
mount.Park();
}
else statusbox.Text = “parked”;
}
else
{
System.Windows.Forms.MessageBox.Show(“mount does not support Park”);
}
}
catch
{
statusbox.Text = “comms error”;
}
}

private void home_mount(object sender, EventArgs e)
{
try
{
if (mountconnected && mount.CanFindHome)
{
if (!mount.AtHome)
{
statusbox.Text = “homing”;
if (mount.AtPark) mount.Unpark();
mount.Tracking = true;
mount.FindHome();
}
else statusbox.Text = “parked?”;
}
else
{
System.Windows.Forms.MessageBox.Show(“mount does not support home”);
}
}
catch
{
statusbox.Text = “comms error”;
}
}

[gustavo]

This is 100% repeatable using the hand controller. It isn’t NINA.

Steps using the HC:

Slew to zenith
Slew back home

It will overshoot and it will not seek home.
Then slew back home again, it will seek.

The issue happens when the slew to home command is triggered from a large degree of distance from home.

If I slew to, say 10 degrees off home, then slew to home using NINA or anything else (hand controller, etc) it works fine.

[buzz]

The same is true using The Sky X - through the Onset ASCOM driver.

The other thing I have noted is that if the mount is powered up in the home position, you need to turn tracking on before it will respond to a park command.

[buzz]

In response to Gustavo - my park position is with the counterweight axis horizontal and pointing to the horizon, so 90 degree off in RA and about 40 off in DEC.

For information - I have updated the firmware and I did not have to update the motors, as I have the SN: 20012407XXXX serial number

[Technical]

Hi Gustavo,

From the second video you posted, the mount slewed to point zenith, and then it returned to home precisely without a stop, by pressing home button on mount.

Have you tried to clear cache by performing Align->Reset Home, and also recreate the NINA profile? It seems that this caused by coordinates stored when you using park functions.

Note: Reset Home in WD-20 will only reset the coordinates and make your current position to home point in coordinates. actual home position will not changed as it only matters with physical home sensor.

Regards.
WarpAstron Support

[buzz]

Are there two issues here?.. let’s say NINA is one of them, but that does not account for those who can cause a poor home alignment using ASCOM commands or the HC, or from other imaging and planetarium applications (which have extensive development)?

[gustavo]

I think there’s only one issue and I think it’s related to OnStep and long slew distances.

I don’t think it’s specific to NINA

[gustavo]

RESOLVED!!
This wasn’t specific to NINA, to be clear. It was actually related to the limits set in the options for the mount. Apparently, if I set the limits to be 5 degrees for both East and West, the slew to home from Zenith seeks just fine.

These are the settings I have which worked for me:

[buzz]

Hi Gustavo, just seen this. I will try it out.

cheers

[buzz]

On your settings you have HA limit as 90 degrees - but won’t that kick in before it goes 5 degrees past meridian?

[buzz]

Gustavo - if you park your mount, unpark and then immediately home, does it home correctly?

On mine, there is definitely the need to let it track for a few seconds before homing. 100% consistent.

[gustavo]

yep, same with mine. have to track for a little before it let’s me home the mount again.

[buzz]

yes - I have just built that into my NINA startup sequence… I’ll respond to your meridian flip question in the thread…