Dock/laptop don't work w/my KVM-based keyboard/trackball.

I am a recent purchaser of the UD-160-A docking station. I am very impressed so far.

In my office at work (where I use the dock), I have several computers connected to an IOGEAR GCS-1744 KVM switch to (obviously) allow sharing a keyboard, trackball and a pair of LCD monitors (as well as speaker & microphone, which I don’t do). When I added my (personal) Dell Inspiron 1545 laptop using the dock my various USB devices, network and the monitors worked fine (some learning about what, where & how for the monitors).

The problem is that the USB keyboard/trackball, through the KVM, aren’t detected. So I have to use the internal kbd/trackpad or a second kbd/mouse set independently connected to the dock. This is inconvenient, to say the least, and defeats the purpose of connecting the laptop to the KVM.

Since I use several computers at home w/a different KVM setup, I would consider another of the GCS-1744’s & another dock for there, if I can resolve this issue for my laptop setup here at work.

Hi - Thanks for posting!

Doing some reading first on the IOGEAR GCS-1744 KVM switch. Will post back soon.

Thanks for your patience,

Hi - sorry for the delay! Looking at the IOGEAR KVM specs for a while, I think I now have the correct picture of how you probably have the devices are connected…

Quick question to help clarify: is the problem actually specific to the keyboard/trackball? For example, does any USB device (like a standard USB mouse) also fail when connected to the KVM, then to the dock, then to the laptop?

Thanks for confirming. Don’t yet have a theory why the devices would have trouble, but it may have to do with anything the KVM is doing that’s outside USB 2.0 spec. Will dig in on that.

Thanks for your patience!

Sorry for my delay, I had a scheduled vacation day yesterday,

I connected another mouse to the “Shared” USB buss, it looked for and found a driver, installed it, and began to work. The “switched” USB keyboard and trackball are still not detected by the dock, therefore, still don’t function.

I’m guessing there are separate USB busses, because the monitors, keyboard and mouse get switched to the desired computer, while the shared USB ports and audio signals don’t have to (but can) be switched also (see pg. 26 of KVM manual). But that leads to the question of why the additional mouse was detected and the desired mouse (t-ball) and kbd haven’t been?!?! Confuses the heck out of me!

Just for kicks, connected a kbd (twin to the one connected normally), to the other “shared” USB port and it also installed and worked.

I’m going to try shutting the whole mess down and seeing what happens if I connect the “normal” kbd/t-ball to the “shared” USB ports and see if all of the computers then work with these devices. I suspect they might. It will be a workaround, but I normally don’t connect a printer, drive, etc. to be shared amongst the computers. I use network connected resources for those purposes and the network is working fine.

I’ll let you know what happens.

The results are: good news and bad news!

The good news is that, having switched the “normal” keyboard & trackball to the “shared” usb ports, all computers function properly.

The bad news is that the KVM cannot be controlled from the same keyboard. To control the functionality of the KVM, I connected a second keyboard to the “normal” keyboard port.

The net result is that, it takes two keyboards to properly perform all the functionality normally required by the KVM and all computers and devices connected to it. This is a workaround at best and is very disappointing. I am truly hopeful that a solution can be found.

Bernie, I am going to send you an email to your attention c/o the support email address.

Hi Bob,

I’m not sure what’s causing the failure through the KVM’s special keyboard/input ports. Clearly they have some extra silicon in there to do things like the detection of key codes to control the KVM (and then pass on the rest of the key codes as normal input).

The one theory I can think of is that USB 2.0 has a limit of doing 5-deep for any given chain of hubs and devices. So I’m not sure, but it seems like you might be going:

  1. keyboard/trackball to
  2. hub on the keyboard/trackball to support those 2 separate functions
  3. keyboard device in the KVM to scan for special commands and repeat the rest
  4. hub in the KVM
  5. hub in the Plugable docking station
  6. Laptop root hub

If you use a “normal” independent keyboard, you save hop #2 and it works
If you use a “normal” USB port that the KVM doesn’t add special logic to scan, you skip #3 and it works
If you don’t use the Plugable dock, you save #5 and it works

So not 100% sure, but I’m suspecting this is what’s going on. It’s a fundamental limitation of USB 2.0, so your only option is to choose how you’re going to eliminate one hop from the chain.

Hope my speculation helps. Thanks for the kind feedback!