Re: [foxboro] Block resource usage listing

Hmm...so does the CP send  _multiple_ messages to the FCM, one to initiate 
the FCM's query of its FBMs, and one or more to check on the 
status/retrieve the results?  How many retries in, say, your average 0.5s 
BPC?  How does this compare to how a CP10/30/40 polled its FBMs?  (Sorry, 
I'm kind of a chiphead about these things :)
Corey






"Johnson, Alex (Foxboro)" <ajohnson@xxxxxxxxxxx>
Sent by: foxboro-bounce@xxxxxxxxxxxxx
04/19/2004 04:16 PM
Please respond to foxboro

              To:  foxboro 
              cc: 
         Subject:       Re: [foxboro] Block resource usage listing






The queries to all FCMs happen at once.

But all FCMs do not acquire their data in the same amount of time. The 
more
FBMs under an FCM the longer it takes to get all the data to the FCM.

The CP waits a certain amount of time to get the data from each FCM one at 
a
time. If the FCM is busy/not ready, the CP waits and retries.

The time for an FCM to retrieve data is proportional to the number of 
FCMs,
but there is variance between FBMs according to the time of FBM and other
items.

Anyway, the query for data is done in parallel. The retrieval of data is
serial. Short chains first (or equal chains) minimizes retries by the CP.


FCMs are slower the FBIs because they read the message. The FBI is not
intelligent; it's an electrical isolator.

Regards,

Alex Johnson
Invensys Systems, Inc.
10707 Haddington
Houston, TX 77043
713.722.2859 (voice)
713.722.2700 (operator)
713.932.0222 (fax)
ajohnson@xxxxxxxxxxx
For the latest information on ArchestrA, go to
http://www.invensys.com/Archestra.html.





 
 
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