RE: EMC vs. Galil Motion card (was: Will emc work for me?)

[cbsled-at-ncia.net]

On 07/06/02, at 04:57 PM, "Craig Edwards" <cedwards-at-ceinetworks.com> said:

>Boards such as the Galil
>receive their commands across the internal ISA or PCI bus, but are still
>somewhat "isolated" from the real time code executing on the primary CPU.

My Galil, (as do they all) has it's own CPU, a Motorola 68331. The primary P166 CPU is running Windows 95, so I strongly doubt there is any real-time action happening there! The Windows end sends raw commands to the card, which does all the realtime heavy lifting itself. All the Windows software has to do is keep the command buffer on the card from running empty and update the screen, tasks which are trivial enough for it to handle most of the time. So on the plus side, the card is not dependent on Windows software and OS in the way a Winmodem is, for example.

>One thing to consider with regard to using a "dedicated" or proprietary
>multi-axis motion control card is that you won't be able to take advantage of
>what I think is really one of the biggest strengths of EMC; it's look ahead
>and trajectory planning algorithms.


You have a good point about the algorithms. I have no control over them. I am stuck with whatever is in the Galil firmware on the card, or perhaps an upgrade if one were available. 

>I apologize if this is getting somewhat off topic from the thread, but I've
>really been putting some effort into understanding the tradeoffs with regard
>to motion control architectures for small multi-axis machines.... and this
>question seemed a good place to bring out this issue. 

I agree.
I am also here investigating my options. Our economic tradeoffs may be different, as I am looking at changing an existing setup, not building a machine. But the price of proprietary control software alone to replace my existing orphaned bugfest would be more than an extensive hardware upgrade or replacement, and even then I would still be stuck with a Microsoft OS and a software vendor who could easily vanish just as fast and completely as the last one did. Open source is the solution to these problems, so I will do whatever it takes to get this machine running on an open source OS and open source software.

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Carl Brown cbsled-at-ncia.net
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