thanks for your quick reply. I tried that but still faced the same issue. Meanwhile i bought a usb hub and connected the mount usb cable through that to rpi. it works.

Meanwhile if I can remove that hub from my setup that would be great. Please let me know if I should try something else to fix it?

Many people using a CEM40 + pi (including ASIAir Pro) have a similar issue. If you try to connect the CEM40 directly to a usb port on the pi, it fails to be recognized during boot-up. If you look at lsusb before starting KStars, the mount will not be there (when it is there, you see an entry for an FTDI usb to serial device). If you look at dmesg, it tries to connect and reports "maybe bad usb cable?".

Either there is something about the usb hub inside the mount that the pi OS usb drivers do not recognize, or (maybe more likely) the mount is trying to draw more power through usb than the pi can provide. So people end up with a powered usb hub in between the pi and the mount.

i did not provide any external power to the usb hub, but it works.

I spoke way too confidently about success with a powered hub, because that was from a week of indoor testing. Hours of solid connection.

It is clear tonight, and within 10 minutes I was back to Read Command Error: Timeout error
I still see the mount with lsusb

How does one "refresh the ports list"? In the CEM40 Connections tab I see only Driver Info


While typing this message, it eventually reported that the CEM40 driver had crashed - would you like to restart. I clicked Yes, but all of KStars crashed at that point.



    

I guess I should ask which hub you bought, and try that one

Sabrent 4-Port USB 2.0 Data Hub with Individual LED lit Power Switches [Charging NOT Supported] for Mac & PC (HB-UMLS) www.amazon.com/dp/B00BWF5U0M/ref=cm_sw_r..._encoding=UTF8&psc=1

Turns out I already have exactly that hub. Swapped it in, and no luck. Read errors started within 5 minutes.

If I cannot figure out a solution soon, I guess I will have to buy a windows mini-pc and start learning NINA

actually i have also tried the hub solution indoors and for less than 5 minutes. let me try it for longer.

I also have trouble staying connected to a CEM40, as described above. In my connection tab, in System Ports, I see FT230X_Basic_D3093ZS7

A longer string containing that is in the Ports line. If I click on System Ports, it turns green. Scan Ports results in the message "one port found".
Is there some meaning to System Ports always starting not-green? Have I done anything by clicking on it, besides making a nice green color?
 

edit: It would appear that I have not done anything useful by turning System Ports green, as after a few minutes there was another Read command time-out error

So many variables in this, and so hard to do experiments.

There's the "pi won't talk directly to the mount" - is that fully corrected by using a hub, or not? Any hub, or just some hubs? If it connects at all, does that mean that the pi - hub - mount communication is settled, and any further communication issues lie elsewhere?
There's some people reporting that the iOptron cable is a problem (even maybe with windows?).
There's the fact that most type-B cables do not fit snugly into the mount's female type-B. The iOptron cable fits best, but still moves around easily when fully engaged.
There's the fact that I have had many hours of successful indoor testing with the same cable setup that failed quickly outdoors (maybe something about the cameras? saw one ASIAir message board post that swapping out the 12v supply they were using for cameras seems to have fixed their connection issue) / (maybe temperature? - but I had a couple of successful evenings late December, they were about as cold as last night).

Current test is in the garage, so not as cold as outside but much colder than the house, with no cameras. I started with the iOptron cable, but snugged up to the 12v plug using velcro as suggested by someone on fb - the idea being to provide some side-load to keep the plug from moving around enough to cause momentary loss of continuity. The fact that lsusb continues to show the mount and iPolar even while getting read timeout errors says that the connection never gets totally lost, but wiggly usb connections are an obvious potential problem.
Left it powered on overnight, with the mount not actually doing anything. It threw read timeout errors all night, averaging one about every 15 minutes, but the driver never crashed and the mount would still respond to commands in the morning. Better, but not confidence-inducing.
Swapped a non-iOptron type-B cable I was using earlier, but now snugged up with the velcro. It has been tracking for 3 hours now with no read errors, so that's encouraging - but experience tells me not to declare this to the the real solution.

Writing that last post felt like venting at the time, but it turns out to have value in laying out all the theories I have read and ideas about maybe what to swap out next.

After running a few hours in the garage with no errors, I mounted the scope and turned everything on just as if I was imaging. Mount errors almost immediately. The main difference? The 12v 10A supply I was using for the cameras and dew heater.

Went and found the 3A supply that came with the QHY183C and swapped it in. So far, no errors. Could this be it? Actually a combination of 'its'. Clearly the iOptron usb cable has issues, but there was also presumably RF noise being generated by the 10A power brick. We'll see. Cloud forecast is iffy for tonight, then nothing looking good for the next week.

Hi Ron,

Most FT232 USB-to-serial chips support baud rate 9600 only. Too fast may cause trouble to connection.

BR//Kenny