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<== Date ==> <== Thread ==>
Subject: Re: USB interface with EPICS
From: "D. Peter Siddons" <[email protected]>
To: Till Straumann <[email protected]>
Cc: Eric Norum <[email protected]>, "Chestnut, Ronald P." <[email protected]>, "Kevin M. Peterson" <[email protected]>, tech-talk <[email protected]>
Date: Mon, 18 Dec 2006 20:58:40 -0500
The only point here is that these little USB motor controllers are very attractive for micropositioning of optical systems, they fit nicely with most optical accessories and are small, including the controller module which is designed not to get in the way when mounted on an optical bench. Motorized micrometers are slow by definition, so who cares if the interface is not super-snappy? It would be nice to have them as part of the scientist's toolkit within the EPICS framework. THere are also USB CCD cameras which are relatively inexpensive. No, USB is not the answer to all, but more and more stuff comes with it.
Pete.


Till Straumann wrote:
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:[email protected]] 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
[email protected]




--Eric Norum <[email protected]>
Advanced Photon Source
Argonne National Laboratory
(630) 252-4793




Replies:
Re: USB interface with EPICS Kate Feng
References:
RE: USB interface with EPICS Chestnut, Ronald P.
Re: USB interface with EPICS Till Straumann
Re: USB interface with EPICS Eric Norum
Re: USB interface with EPICS Till Straumann
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