Thank you Rob, and good to understand how the INDI driver and the USB-serial driver are two independent issues.
Based on Peter's other post, I have installed the CP210x driver for MacOS, version 6.0.2. In Kstars I can now choose between the Apple driver (cu.usbserial-2130) or the Silicon Labs driver (cu.SLAB_USBtoUART). Neither work and both give the same error message of not being able to retrieve the serial number from the focuser. Based on your comment that in most cases the issue lies with the USB-serial driver, perhaps there's something I've done wrong with installing it. But it is recognised in KStars, so I would not know what else to check.
Neither the driver packaged with the Webmanager app version 1.6 nor the driver packaged with KStars 3.5.5 can make the connection. Peter was saying that for him the Webmanager app worked, but he noticed that the INDI driver was different than what was packaged with KStars. If Peter has an earlier Webmanager app installed than 1.6, we could look at the differences between the INDI driver packaged with that version (which works) and the current and improved INDI driver (which does not work). Perhaps that might give us a clue as to what is going on?
The problem just went a whole lot bigger (I guess this was to be expected...). I tried the Sesto Senso 2, and it has the same problem. No connection, whatever combination of serial driver and baud-rate I choose. Constantly the same error of not finding the serial number of the focuser.
With two scopes having a Sesto Senso 2, and one having an Esatto, this essentially means that I can not use my Mac mini, that was specifically bought for astro, to run any of them....
Hopefully we can find what's the issue here, and find a fix for it. Any suggestions welcome.
Just something to bear in mind, that I have found with my SestoSenso2 and the INDI driver (on Astroberry).
If I start INDI, and the following are all true:
I have devices set to automatically connect at startup
I have the devices set to auto-detect the serial port at startup
Then, if I have had a problem with the SestoSenso2 connecting, and I go to disconnect and stop INDI in Ekos I often find that the indi_sestosenso2 driver is actually still running, and hasn't stopped. I either have to manually kill that process or reboot Astroberry before I can attempt to re-connect the sestosenso2 driver.
Because of this issue, I have now disabled any serial port auto-scanning in INDI, and have all my serial devices to manually connect to a specific serial port in the /dev/serial/by-id/ folder.
One other thing I noticed. The now installed USB-serial driver is referred to as CP210x driver. The apple driver is usbserial-2120 (and if using the other USB-port: usbserial-2220). None of these labels mean much to me, but would one need a CP21xx driver or so?
I’ll check which version WebManager I have, but honestly I doubt I will be using it. My gear is connected directly to my old MacMini and runs well. I just use Mac’s screen sharing to control it from my home as needed, otherwise I just use it directly from the control room. I’m not sure if I did anything else but my Esatto connects with and without IndiWeb Manager.
iOptron CEM120 EC2 and CEM25P
Celestron C11 EdgeHD
William Optics Star71
ASI 1600Mm Pro, ASI 462MC
Moonlight motorfocus & Esatto focuser
LodeStar X2 and ZWO OAG
Great to hear you have no issues connecting to either webmanager or directly. Your webmanager uses version 0.4 of the driver. Would be interesting to know which driver you use for the direct connection. If that's version 0.7 (like I have), the problem is not in the driver. If it is anything else, there might be an issue with the driver.
In the meantime also tried a MacBook Pro from 2016, and it has the same problem, so it is not related to M1 Macs.
I also tried the available legacy version 4 of the VCP driver (current one is 6), but also gives the same problem.
Thank you @Peter Kennett, those are the same versions as I am using. So good news is that it can work. Will have to dig further into why it won't work on my side.
Perhaps one more thing to check: what MacOS are you running? Looking at the wallpaper, would that be Mojave?
I just heard someone else who encountered USB/Serial connection issues popping up when updating to Big Sur, so perhaps it could be MacOS related....