Cannot enable Powerlinc 2413U after installing Wacom tablet

I purchased a new iMac about two weeks ago and successfully transferred Indigo 7.4.1 to it and got my reflector activated, etc. Everything was working fine. Yesterday, I installed a new graphics tablet, a Wacom Intuos Pro tablet and after that lost the ability to connect with the Powerlinc or enable or disable it. I turned off the tablet, disconnected it from the computer, switched out the usb cable, unplugged the Powerlinc, rebooted, etc., without benefit. Fortunately, I had an unused older laptop running Mac OS 10.13.6 and again transferred everything to this "new computer," that did not have a tablet installed. After struggling with the transfer and reflector activation, everything worked perfectly with the same Powerlinc, usb cable, etc. This proves, I think, that the problem is the tablet and its drivers.

I found an old post about someone who had intermittent problems with a Powerlinc after installing a tablet but little else. Anyone with insight into this problem. I've got the system working but now need two computers to do what always was accomplished with one before.

Thanks

[jay (support)]

Did you try moving the tablet to different usb ports/hubs? It definitely sounds like the tablet is the issue, but it's unclear if it's a driver issue or a USB contention issue. Do some research on your iMac's USB layout and try making sure that the PowerLinc is on a completely different USB bus from your tablet - that might help if it's a contention issue.

The 2020 iMac has 4 USB-A ports on the back. I tried a different cable and did switch from its original placement to an adjacent port (just one.) I’ll look into how the four ports are configured. I know that for most iMacs, there are two thunderbolt ports available but they share- if that’s the right term- a single bus.

I’ll look into the USB issue as you suggest.

Thanks

The 2020 27” iMac appears to have a single USB 3.1 bus which is labeled as “composite.” If the graphics tablet is running I can see how it might interfere with the USB connection to the 2413U. However, when I disconnect the tablet from the computer and remove the USB cable, the problem persists. It seems to me that the Wacom driver is the problem. I don’t think there’s much that can be done about this although i think it likely that at least a few Indigo 7 users also use a graphics tablet from Wacom and either do or do not have this problem.

Any thoughts?

Thanks

[jay (support)]

These kinds of issues (low-level USB issues) are always super hard to diagnose and figure out if/how to workaround. Have you tried plugging the PowerLinc into a USB2 hub rather than directly? Not sure if that'll help, but it has made differences in other scenarios.

Not sure I've ever heard of anyone successfully using a tablet with a PowerLinc at the same time. There have been issues with hard drives on the same bus as the PowerLinc in the past, but I haven't heard of that kind of issue in several years, so I expect the macOS USB subsystem was tweaked to handle that scenario.