[Halld-controls] Ethernet switch reliability and PLC control

[Elliott Wolin]

Hi,

At the Controls meeting yesterday we discussed the reliability of PLC 
control using Ethernet as the chassis interconnect mechanism, as 
compared to ControlNet, which uses a custom cable and protocol.

Today I talked with Bryan and Brent about network switch reliability.  
They said the equipment they are buying these days is extremely 
reliable, as reliable as the PLC itself.  About the only switch failures 
they ever see are due to loss of power.  They say that as long as all 
the switches in the PLC control path are on UPS power we should not have 
any problems.

Thus I conclude we do not need to consider using ControlNet as an 
alternative to Ethernet/IP for the PLC chassis interconnects.  Note that 
we own two or three (expensive) ControlNet modules that we may be able 
to sell to Hall C, who uses ControlNet mainly because the Ethernet 
option was not available when their system was designed.

Comments...?

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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