[Halld-controls] Possible solution to solenoid coil tap problem using NI CRio

[Elliott Wolin]

Hi,

Yi may have come across a great solution to our coil tap isolation and 
voltage range problem, i.e. how to feed coil tap voltages to both the 
fast and slow DAQ systems while maintaining isolation and covering the 
full voltage range at the required readout speeds.

A while back I proposed using a National Instruments Compact Rio system 
for the FCAL CANBus system.  At the time it was fairly expensive and 
Matt came up with a cheaper solution using CAN-Ethernet converters.  
CRio isn't competitive for low-end applications.

But Yi discovered that 1) prices have dropped and 2) CRio is competitive 
on high-end electronics systems, e.g. for our large voltage range fast 
DAQ system.

But if we use CRio for the fast DAQ we get a great bonus:  it has high 
enough resolution to meet the needs of the slow DAQ system, and it 
appears likely that CRio can talk directly to our A-B PLC via 
Ethernet/IP.  That is, as far as PLC programming is concerned, the CRio 
system is just another chassis.

Further, if the CRio system does work as above it solves the isolation 
problem as well, since now a single device can feed both the fast and 
slow DAQ systems.

Finally, if CRio works out we even save money because we would not need 
hard-to-find isolation amplifiers that cover the full coil tap voltage 
range and bandwidth.  In essence, the CRio system combines isolation 
amplifiers, ADC's and PLC-compatible readout in one device.

CRio appears to give us the ability to connect high-end electronics to 
the PLC.  I've also heard rumors that CRio can run a Channel Access 
server and thus can talk directly to EPICS, not sure we need this 
feature for the Solenoid controls system.

Everything above needs to be verified, but it looks good at the moment...

Thanks,

-- 

				Sincerely,
					Elliott


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  Those raised in a morally relative or neutral environment will hold
		    no truths to be self-evident.
				

Elliott Wolin
Staff Physicist, Jefferson Lab
12000 Jefferson Ave
Suite 8 MS 12A1
Newport News, VA 23606
757-269-7365

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