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National Instruments DAQ API troubles

Feb 15 2006 | 8:10 am

Hello all,

I am writing an external that enables access to the analog and digital inputs & outputs of the National Instruments USB 6008, an inexpensive ($150) and compact USB DAQ with pretty good performance. An OS X API is available from NI, which is what I’m using.

I have been able to access all the capabilities but not without some odd side-effects.

When the NI code is called for the forst time within Max, the program freezes for several seconds, after which it works pretty quickly. However, in every case where I run the NI code, Max stops responding to the Quit command (command -Q or the menu item), and can only be shut down using Force Quit.

The NI API for OS X is not thread-safe according to the readme files, so I put all calls to the NI code in critical regions. This doesn’t eliminate the problems, though.

Any thoughts or interest in working with me on this?

Thanks a lot,
Aaron aka Dr Friendly

Feb 15 2006 | 6:06 pm

Can you spawn another thread that inits the NI code? I understand
that it’s not thread-safe, but if all of the calls to the NI stuff is
happening from the same thread, you should be okay. I’ve had similar
problems with open / save dialogs in Carbon apps when I have some
sleeping media attached to the machine.

You might be causing your main thread (that binds to the runloop) to
block. This will block all processing of AppleEvents, including the
quit event, in addition to mouse events etc.


Jun 23 2007 | 4:58 am

if you are still interested i have done a very simple and very beta-version of such an external… many things to do but it goes

let me know,
cheers, Alfredo

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