David McLean writes:
> I'm looking at trying to control various RS-232 devices over a
> network. 

I've had good luck with an old-school ethernet<->serial interface from
Intelligent Instrumentation:

  http://www.edasce.com/rs232-ethernet-interface.html

It's not USB, but does do the job you describe.  I'm able to plop a hub
out there on the detector and control multiple RS232 devices through an
ethernet connection.  They provide C networking libraries which
compile fine under linux.

-- 
 	    Alec Habig, University of Minnesota Duluth Physics Dept.
	    		    [log in to unmask]
		       http://neutrino.d.umn.edu/~habig/