USB Communication with NXT Robot fails in download and runti

[wschilling]

I'm at whits end. I am trying to build a simple robot that response to PC commands via USB. I have tried the demo code an it works fine. However, since running and successfully starting the Bluetooth demo code, I am now unable to download code reliably over USB and can not talk to the robot over USB. I am running WIndows 7 64 bit, though I have a 32 bit Java version installed. Right now, if I try to download code from the Eclipse plugin, I receive the following error message:

leJOS NXJ> Linking...
leJOS NXJ> Uploading...
Found NXT: Unknown 001653094017
leJOS NXJ> Failed to open Unknown 001653094017
leJOS NXJ> Failed to connect to any NXT
an error occurred: No NXT found - is it switched on and plugged in (for USB)?

If I start nxjbrowse, I can see my robot but the status is disconnected. If I click on connect, the Failed to connect dialog appears. I was able to talk once earlier this evenign after rebooting my laptop, so I really feel its a USB driver problem, but I'm not sure what to try next. On the mindstorm, I have turned off bluetooth. Based on a search of the forum, I tried deleting the nxt.cache file. No such luck... Any other ideas?

When I try (right now) to download through Eclipse with lejos downlaod, I receive the following:

leJOS NXJ> Linking...
leJOS NXJ> Uploading...
Found NXT: Unknown 001653094017
leJOS NXJ> Failed to open Unknown 001653094017
leJOS NXJ> Failed to connect to any NXT
an error occurred: No NXT found - is it switched on and plugged in (for USB)?

As I mentioned above, I have WIndows 7 64 bit, but I am running a 32 bit JVM.

[gloomyandy]

Hi,
Have you tried restarting your NXT (or unplugging the USB cable). Also are you sure that your program is not still running on the PC. It sounds like you have either got the NXT USB code into some sort of unstable state (did you NXT program close the USB connection before it exited?), or you have the USB connection open with more than one program...

Andy

[wschilling]

Andy:

Unfortunately, that was tried as well. I tried unplugging the mindstorm from USB, cycling power, removing the battery, etc. No luck.

That being said, this morning things seem to be a bit more reliable. I powered both the robot and laptop up after being turned off over night and I can reliably download to the robot. I guess the robot was more tired than me...

[Philipp15b]

I have the same problem, but I've found a rather annoying solution: I have to restart my computer every time this issue appears, then it works for some time....

Edit:
The NXJ Control Center shows this NXT all the time as:

Code: Select all

Name     |   Protocol    |  Address        | Status
Unknown  |   USB         | 00165301C7A8    | DISCONNECTED


[Philipp15b]

It seems that a running "zombie" program ran and tried to communicate with the NXT. I just had to close it

[skoehler]

An NXT is shown as unknown, if another program is still running and talk to it.
Also, the Fantom driver doesn't always allow us to connect to the NXT in case a program has abnormally terminated the connection to the NXT. A solution is to terminate all Programs that might be talking to the NXT, and retry again.

A reboot is usually not necessary.