usb serial not working on usb hub

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usb serial not working on usb hub

I'm trying to use a serial console to a small device via USB. The USBSerial interface is a CH341 chip. The odd thing is that everything works fine when I directly connect the CH341 to my MacBook directly, but if I run the USB through a hub if fails. Even stranger this behavior is NOT observed on my Win10 Laptop. There it works fine. I would suspect a driver issue on the MacBook, but it works ok when connected w/out the Hub. So the driver seems to work ok. But something gets confused when the hub is in the way, and only on the MacBook not Win10. I'm running the MacOS 11.2.3. Anybody have any clues?

Even more annoying, if I do a system report to look at the USB devices, it shows up even on the hub. So MacOS somehow does see the serial device, but it can't seem to find it when I try using screen or minitab.

MacBook

Posted on Apr 6, 2021 5:09 PM

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Answer 1

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zeefour Author

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Apr 8, 2021 4:11 PM in response to zeefour

Problem resolved... As it turns out what was actually happening is that the device name changed just slightly when moving from direct connection to the MacBook vs. the USB Hub. So if I use the correct device name for the appropriate connection, it works as expected. The only issue was the names were very similar and I didn't inspect the name carefully enough to noticed that it had changed. Ugh...

Kind of a pain that just moving the USB connection should completely change the device name though. Reminds me of moving COM port numbers on Win32 *grin*.

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Answer 2

Apr 7, 2021 11:14 AM in response to zeefour

Hey there zeefour,

Thanks for reaching out to Apple Support Communities. We understand you’re having an issue using a USB hub with your Mac. We’ll be happy to help with this.

The following articles could provide a solution to this issue. They both address issues with devices connected to a USB port so be sure to review the steps in both:

If a USB device doesn’t work with Mac

If a Mac accessory needs more power or is using too much power

We hope this helps. Take care.

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Answer 3

zeefour Author

Level 1

4 points

Apr 7, 2021 2:00 PM in response to barberlives123

I've already checked all those references and then some. As I stated, the device (a small 6502 8-bit computer with a TTL serial interface) connects to a serial-to-USB board,, then to an ANKER USB hub, and finally to the computer. This chain works fine to a PC and also works fine to the MacBook (without the hub). So sufficient drivers and power are available. It fails to work only when the ANKER hub is in the chain and only the MacBook. The hub is powered and as stated works fine with the PC, just not with the MacBook. So I'm stumped. I've also tried resetting the NVRAM and SMC with no change to the behavior.

When it fails I get "minicom: cannot open /dev/tty.usbserial-1410: No such file or directory" even though the file exists in /dev AND works fine in the other scenarios.

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Answer 4

Apr 7, 2021 2:47 PM in response to zeefour

Hey zeefour,

If those steps did not help, you may want to reach out to Apple Support directly using the following link so they can look further into this with you:

Contact Apple Support

Kind regards.

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usb serial not working on usb hub

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