Does it do some kind of query to the focuser device to learn the present position? Is there some action that can force this to happen?
Or does it just record where it last was and imagine that it's still there?

Many (perhaps most?) focusers report their position to the INDI driver, which in turn sends it to Ekos.
So, Ekos gets told the focuser position.

Internally, the focuser firmware will very likely do as you said: "record where it last was and imagine that it's still there".
Hy

Thanks, Hy.

>>Many (perhaps most?) focusers report their position to the INDI driver, which in turn sends it to Ekos.
>>So, Ekos gets told the focuser position.

I assume this happens when INDI starts and connects to the focuser. Is there any logging of what it reports?


>>Internally, the focuser firmware will very likely do as you said: "record where it last was and imagine that it's still there".

Some focusers have the ability to be twiddled manually. How would this be accounted for?

The ZWO EAF has an optional hand paddle that you can adjust the focus manually. But when you use it, it does adjust the count in the EAF itself. And that's why I have one for each of the units I have. It makes it handy whenever I want to do live viewing with the scopes also.
There may be some EAFs out there that has a clutch to disconnect from the shaft, but I don't see any way those can keep up with the number of rotations on the device with the focus assembly travel since they are not bound to each other any longer.
Not really different than when you loosen the clutch on your mount and move your scope. It may say it's pointed one location but once you moved it manually that location fix no longer applies.

> I assume this happens when INDI starts and connects to the focuser. Is there any logging of what it reports?

I assume most drivers will query the focus position regularly, e.g. every second. Mine does.

If you enable driver logging for your focuser, you'll probably see these values, though I suppose that depends on the driver.

Hy

I assume most drivers will query the focus position regularly, e.g. every second. Mine does.

If you enable driver logging for your focuser, you'll probably see these values, though I suppose that depends on the driver.

Sigh, I don't think you're correct in the case of ZWO-EAF. I have debug driver logging enabled on my ZWO EAF, and I see no queries whatsoever being made. The driver seems to simply assume that its initial position is the last one saved.

I tell the focuser to go the position 38000. It moves somewhere. I disconnect devices, shut down KStars and Ekos. I bought an accessory that Starizona sells, along with the EAF. It has a screw that loosens the clutch and allows hand-turning of the focus knob. I do so. I then tighten the clutch screw back. I turn everything on and still see the current position is 38000. Clearly, the driver has no idea where the focuser knob actually isl The "current position" is just some relative number. Any moves in and out simply add and subtract from that. I don't think the ZWO-EAF allows such queries to be made, but if it does, the driver doesn't support this. So if you touch the knob, you've lost any relationship the device may have had to its actual physical position.

Tracy, I don't have the ZWO hand paddle. I looked it up online. It's called the "Hand Controller for EAF". The thing Starizona sells is mechanical. The paddle looks like a good idea, much better than Starizona's device because it stays with whatever numbering scheme you set up. The ZWO manual mentions the need to set the 0 position. The INDI driver configuration seems to offer similar functionality. ZWO recommends the 0 position be set to the "fully retracted" position. Would that be all the way counter-clockwise or all the way clockwise? I assume it's the former.

For at least my focuser, and likely many others, the "position" that's tracked really means the position of the stepper motor that turns the mechanical focuser. It does not mean the position of the mechanical focuser. (I suppose it's possible to keep track of that with optical sensors etc, but that's likely not being done.) So, if you detach the clutch and manually turn the mechanical focuser, I believe you are right that INDI/Ekos and the focuser controller itself lose track of the mechanical focuser position. However, if you use a focuser controller's user interface to step the focuser, then I would hope that the focuser controller (and INDI/Ekos) could keep track.