Re: Mach2 thru-mount USB when using USB 3.0 ? (and an M51)

Dale Ghent

On Apr 11, 2021, at 02:27, Jeffc <> wrote:

i've been troubleshooting an issue with a new camera (QHY268M) (and of course new-to-me drivers).

This is the second night I've had the QHY268M up and running.
The reliability of getting images out of it has been very hit and miss for me.
I'm using the Ascom QHY drivers, but also noted issues with "native driver" capture apps.

The reliability issue seems to be cable related:

-- It turns out if I run the USB 3 cable direct from the camera to the computer then it seems reliable. (I'm still testing this configuration for "longevity".)
-- However if I run the cable "through the Mach2 mount", then the connectivity is kind of flakey. Sometimes the downloads just don't happen. Sometimes the camera disappears from the win10 Device Manager.

Works: Camera --> USB-3-B--cable--USB-3-A --> Computer
Is flakey: Camera --> USB3-B--cable--USB-A --> Mach2 --> USB-A--cable--USB-A --> Computer

Two rules with USB3:

1. Keep cables runs between powered equipment short. I don't do runs more than 2m.

2. Use quality cables. "Amazon's Choice" cables are a dice roll, so just source cables directly from a decent manufacturer. L-Com, for one, but StarTech and Tripp Lite seem to source their cables from some place decent, too.

USB3 far less tolerant of distance and interference than USB2 is. You have to plan to these aspects. USB3 unpowered USB3 extension cables are unreliable in my experience. They add too much length to the total run in a lot of cases, their own construction quality might not be great, and of course there's the extra issue of just having two more physical connections in the line.

For my two QHY-based rigs (Mach1/130GTX/QHY600M and RST135/CFF92/QHY268M) I put a USB hub on the top of the telescope and run all on-scope equipment to that. In my case, the USB hub is a Pegasus Ultimate Power Box v2 or Pegasus Pocket Powerbox Advanced, respectively. A 2m USB cable comes off that and, on my Mach1, goes through the mount and directly into my imaging mini PC. My one PC drives both rigs at the same time, so I can't really keep it mounted on the telescope like many do now.

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