Time controlled Loop faster than 1ms

[Ben]

"

Bad news for the original poster, Steffen:  I don't think a USB-based board will work nearly as well for this stuff (perhaps hardly at all) as a PCI card.

"

I would suspect the same. The hardware timed Timed Loops appear to be clcoked by the interupt service routine and since USB can't assert PCI bus interupts...

Ben

[Ray.R]

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Ben wrote:

" Bad news for the original poster, Steffen:  I don't think a USB-based board will work nearly as well for this stuff (perhaps hardly at all) as a PCI card."

I would suspect the same. The hardware timed Timed Loops appear to be clcoked by the interupt service routine and since USB can't assert PCI bus interupts...

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Ditto.

Plus you need to learn the "tricks", which under "controlled" situation, you might get away with, but for precise timing, you'll need a better OS than windoze. 

Has anyone experimented with Linux???

RayR

[PhillipBrooks]

There was this post a while back where someone was asking for "change detection" on USB.

I searched the forums and read that some of the the M Series High Speed USB devices have support for edge change detection. This should be able to drive a timed loop, but the question would be "How fast will it go?"  Anyone out there with an M Series USB device (non bus powered) and a function generator that wants to perform a test?

Message Edited by Phillip Brooks on 12-14-2007 06:42 AM

[PaulG.]

I've done non-RT but deterministic, faster than 1KHz DAQ, non-National Instruments hardware with GaGe products.

http://www.gage-applied.com/products/pci_family.htm

I'm sure there are other manufacturers of similar boards. You will need an external trigger and a DAQ board capable of buss mastering. The scope board essentially takes over the bus during acquisition. With a sufficiently deep memory you get all the determinism you need. These boards are not cheap, but cheaper than an RT system. And you can write/develop/debug your code on your PC at your desk.