Re: [foxboro] OPC again...

Personally, I would only use it in the manner Alex described: using a 
watchdog in the CP with fallback logic and control.  Doing control with 
anything that requires Windows and DCOM makes me nervous, but if it's 
supervisory (like APC), you can at least implement a secondary mechanism. 

Most of the installation guides I've seen recommend opening things up wide 
to ease getting DCOM working properly, which of course is derimental to 
security.  I have always taken that advice to heart, or avoided DCOM 
entirely by putting client and server on the same box.


And I've always heard a persistent rumor that writing to the I/A via OPC 
(not sure of the mechanism, maybe AIM*OPC?) was not a very high bandwidth 
proposition, but again, this may either not be true, or not an issue 
depending on the size of the APC.


Corey Clingo
BASF Corporation






"Joseph M. Riccardi" <Joe@xxxxxxxxxxxxx> 
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[foxboro] OPC again...






Folks,
I have always wondered if OPC was not just intended to collect data, or is
it also considered a viable communication link for control?  I now have a
vendor that wants to perform advanced process control from their PC-based
software to specific control loops on the Foxboro System via OPC?  Read
measurement values, execute advanced control algorithms, write control
outputs, etc.
Is OPC considered secure, reliable, repeatable, etc. enough for control?

Your thoughts/recommendations?


Joseph M. Riccardi, Inc.
DCS Services - Industrial Process Control

North-Central Office (OH, PA, MI, IN, WV Area)
South-East Office (FL, GA, AL, SC, NC Area)

Joe@xxxxxxxxxxxxx

"To give real service you must add something that cannot be bought or
measured with money; and that is sincerity and integrity." - Donald A. 
Adams




 
 
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