No active ports detected

[paul_z]

I have a PRT Alpha and thought the following info might be useful to others. I lost control of the bot and the PC software could not find an active port. I cycled power on the control computer and on bot several times. No luck.

An obvious possibility was the powered USB hub that I was using. It stays powered up 24/7. Before replacing the hub, I cycled power on it. The system started running again. Been running 6 hours with no issues. Seems as though the firmware in the hub was messed up. Hub replacement not necessary!?!?

Might want to add "cycle USB power" to the list of things to try when "the darn thing just won't work".

[Brady Watson]

Check your computer's power management scheme. Some of them suspend the USB power after a certain interval.

-B

[paul_z]

Brady,

Thanks for the suggestion but my computer is an older desktop and doesn't have that type of power management. The problem also showed up immediately after power up.

I should probably explain more about why I started this thread. The root problem was that the USB hub was messed up somehow and only needed a power reset to fix it. It had been running 24/7 for four years. Although it was surge protected, we get heavy thunderstorms here and grey outs in the winter.

If I had simply replaced the hub, the new one was likely to work and I would have thought the old hub was bad. The problem with that approach is that I would have still left the new hub powered 24/7. I would have also replaced the old hub with a new one that might have even lower reliability.

The old hub has been working now for over a week after power reset. It ran four years without a problem; If it does that again, I'll be very happy.

I've spent almost 1/2 century creating and debugging systems from simple to extraordinarily complex. I learned early (and of course the hard way) that if you have the time and resources, run the problem to ground. Once you uncover the root cause, you can make much better decisions on how to fix the problem.

Paul Z

[Brady Watson]

Roger that, Paul.

Don't underestimate the inevitable fact that electronics degrade over time, especially capacitors. Sometimes caps on the bus get fried, bloated or otherwise tired; which causes problems down the pipeline. Not sure if you can get a PCI to USB expansion card in whatever PCI flavor you have on your MoBo, but that would be where I would begin after exhausting the obvious.

The el cheapo Amazon Basics USB hub works beautifully on USB to Serial converted cards, as well as the newer USB direct cards in my experience.

Hope you get it sorted...

-B

[paul_z]

A week after a power reset, the hub is still running perfectly (as far as I can tell).

[paul_z]

Update

Almost three months later and the old hub is still working fine.

Paul Z

[barrowj]

Paul,

Have you considered moving the power supply for the hub to a switched power source that you will turn off when you turn the system off? Maybe a surge strip that you could turn the entire system off with (computer, monitor, etc), that would save excess wear and tear on hub and potentially eliminate the issue you had.

Joe

[paul_z]

Joe,

I think you are right and I was planning to do that. I ran this test wondering how many people replaced the hub and thought that was what fixed the problem. I hope that the result of this experiment will reduce the number of times "I had to replace my hub to fix my bot" resulting in unnecessary delay and cost.

Paul Z