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<== Date ==> <== Thread ==>

Subject: Re: USB interface with EPICS
From: Till Straumann <strauman@slac.stanford.edu>
To: Eric Norum <norume@aps.anl.gov>
Cc: "Chestnut, Ronald P." <ronc@slac.stanford.edu>, "Kevin M. Peterson" <kmpeters@anl.gov>, tech-talk <tech-talk@aps.anl.gov>
Date: Mon, 18 Dec 2006 15:41:49 -0800
Eric Norum wrote:
True, devices on the USB can not make unsolicited requests for service. But that's not a show-stopper. Consider all the GPIB devices in use which do not use the SRQ line -- the situation in that case is quite similar.

USB controller chips do have interrupts so it's not necessary for a device driver to continuously poll some register in the controller to see when a message has arrived.
True - I just wanted to make the point that this in some
cases [when low-latency is critical] could be a show-stopper
for USB.

T.

On Dec 18, 2006, at 4:06 PM, Till Straumann wrote:


Just a side note before becoming excited about USB:
AFAIK (but I could be wrong), USB has no real interrupts
but always works in some sort of 'polled' mode. There could
be latency issues with USB devices if you need really fast response.

-- Till

Chestnut, Ronald P. wrote:
Kevin,

At SLAC, one of the RF physicists started using USB. To keep matters simple, he developed subroutines with which he could write to and read from USB. We then hook these in with subroutine records when time comes to put EPICS on it.

I'd also like to see some real USB driver-supported stuff.

Ron Chestnut
-----Original Message-----
From: Kevin M. Peterson [mailto:kmpeters@anl.gov] Sent: Monday, December 18, 2006 7:44 AM
To: tech-talk
Subject: USB interface with EPICS



Is anyone using the USB interface with EPICS? Of particular interest is the ThorLabs APT series.


Thanks,

Kevin Peterson
kmpeters@anl.gov




--Eric Norum <norume@aps.anl.gov> Advanced Photon Source Argonne National Laboratory (630) 252-4793




Replies:
Re: USB interface with EPICS D. Peter Siddons
References:
RE: USB interface with EPICS Chestnut, Ronald P.
Re: USB interface with EPICS Till Straumann
Re: USB interface with EPICS Eric Norum

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