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Cannot Switch Between 2 ZWO Focusers

Posted: Fri Jan 09, 2026 11:08 pm
by Harmonious
I have a side by side setup. One scope has a recent ZWO EAF (USBC not pro or network) and the other has an older ZWO EAF (USB signal+12V power).

In the SC Pro hardware tab the newer EAF is listed as ZWO Focuser (1) and the older is ZWO Focuser (2). Focuser (1) is associated with a ZWO2600. Focuser (2) is associated with a Player 1 Poseidon.

If I check the properties of ZWO Focuser (1) a ZWO app opens. Focuser (1) in SharpCap is EAF 1 in the ZWO app. The correct step number is displayed. I close the ZWO app and the hardware tab. The camera controls show Focuser (1) is connected and the step count is correct.

If I close the camera in SC open the hardware tab and select Focuser (2), the ZWO app opens, shows EAF 2 and the correct step count. When I open the camera associated with Focuser (2), Focuser (2) shows in the camera controls but with the step count from Focuser (1). If try to adjust the focus it is Focuser (1) that moves and not Focuser (2).

No matter what I close, restart or wave a feather at, SharpCap when Focuser (2) is selected after Focuser (1) SC will show the step count for (1) and send commands to (1) even though (2) is selected in hardware and (2) shows as the connected focuser in the camera control.

If I disconnect (1) and restart SharpCap and select the camera to which (2) is associated, it loads (2) and displays the correct step value.

Re: Cannot Switch Between 2 ZWO Focusers

Posted: Sat Jan 10, 2026 12:29 am
by AstroChessPilot
This thread might help some.

viewtopic.php?t=8955

Re: Cannot Switch Between 2 ZWO Focusers

Posted: Sat Jan 10, 2026 2:53 pm
by admin
Hi,

yes, that thread has some good info on this. The consensus seems to be that it is a problem with the ASCOM driver - I think it stores the focuser to use as an index number (zero, one, etc), but those index numbers are not stable from one run of the application to the next, so that a focuser that is index 1 one time is index zero the next.

The right thing to do would be to store the serial number of the focuser (they seem to have a serial number) - then it wouldn't matter if the focusers got different numeric ids, the ASCOM driver could just try each until it found the serial number it wanted.

As always with this sort of thing, it's probably worth making sure you have the very latest ASCOM driver version as an update might just fix an issue like this.

I had hoped to be able to check this myself as I thought I had 2 EAF devices - I even had two purchase confirmation emails, but when I investigated further I found that I only had one and the company I bought it from had sent out a duplicate purchase confirmation email several months after my actual purchas :(

cheers,

Robin