Trouble installing Enchanting

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Trouble installing Enchanting

Postby laughlin » Mon May 27, 2013 12:39 am


I'm having trouble.

Mac OS X 10.8.3 (Mountain Lion)
JDK 1.6.0_45
Fantom 1.1.3

Flashing NXT using tool in Enchanting works fine via USB connection. NXT claims running leJOS 0.9.1(rev 6595)

Bluetooth pairing appears to work.

Run, Upload and Stop icons are all crossed out, and pressing them generates the error "No communication with BackEnd".

I have been through the leJOS Mac how-to, with no luck.

And yes, I have restarted machine, used an admin account, unplugged and replugged USB, tried bluetooth / no bluetooth, restarted Enchanting. No joy.

Please help! My son really, really wants to do this.


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Re: Trouble installing Enchanting

Postby clintonb » Sun Jun 16, 2013 2:51 am

Hi Laughlin.

I'm so sorry for the delay in replying. I'm been busy and my mind has been elsewhere.

I'd really like this to work for your son.

"No connection with backend", eh?

Enchanting is a little convoluted. There are two parts to the program:
1) The Front End. This is the user interface, based on Scratch. You edit code here.
2) The Back End. This is behind the scenes, and written in Java. It talks to the NXT.

The Front and Back End speak to each other using a network socket -- really, very much the same way your computer speaks to a website. If the front end and back end aren't speaking, you get the error message in question.

There are three ways this happens, primarily:
1. you start the Front End directly, and not the Back End. Make sure you aren't running ''; you need to run ''. [If you run '', it starts the back end, which then runs the front end. If you try to put it on your Dock while it is running, you'll get just the Front End application, and starting it that way next time will not work.] I have attempted to reduce the likelihood of this by making Enchanting issue an error message if it doesn't see the Back End within a minute of starting [but that's been a little problematic on slow platforms.]
2. The Back End crashes. It can die without you knowing it, and then there is no communication. : (
3. Your firewall prevents the local network socket connection between the Front and Back End applications.

Let me suggest that you run Enchanting in verbose mode. Do this by navigating to the Enchanting folder and double-clicking on "verbose_enchanting.macosx.command" in the Finder. When you do this, you get a black terminal window showing white text -- this is the Back End speaking. You also get the regular user interface. Make sure they can see each other -- try clicking on some of the buttons, like the green flag, and you should get "No device connected" [which is fine] instead of "No communication with the back end".

If you do get the "No communication with back end" error, see if the Back End shows evidence of a crash. It would have several lines of output talking about an Exception as a specific place in the code.

The USB connection should work very fine. With no other program open that talks to the NXT, try running "Browse Files.command" in the Enchanting folder (by double-clicking on it in the Finder). This runs a leJOS tool that will let you see the files on your NXT and rename or delete them. If it doesn't see the NXT when you plug it in, something weird is going on. However, your symptoms do not suggest a problem in the connection to the NXT; only a problem with the two parts of the program communicating.

Hope that helps.

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Re: Trouble installing Enchanting

Postby laughlin » Sat Jun 29, 2013 5:28 am


Thank you so much! This was so simple.

As you said, I had EnchantingFE in the dock and was running this. Running Enchanting now and no problems. My son is very happy!

Thanks for all the hard work with this great application.


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