Re: [foxboro] Matrikon OPC Server for Foxboro I/A
- From: Terry Doucet <doucet427@xxxxxxxxxxx>
- To: <foxboro@xxxxxxxxxxxxx>
- Date: Wed, 16 Mar 2011 11:17:46 -0400
List,
I have not seen a problem over the years with getting large numbers of C:B.P
out of the Foxboro servers (off the node or off the mesh). The 7000 listed
below is very credible. The issue is usually the on-node or on-mesh traffic
between the AW server and the source station for the C:B.P. For AIMAPI or
FoxAPI the parameter fastest_rsr determines the scan rate from the source
station to the AW server. For huge numbers of C:B.P, the fastest_rsr likely
needs to be 10 seconds or slower. My recollection is that 20 seconds was the
norm in most plants that I visited.
On sites where the fastest_rsr was mistakenly left at a very fast rate, the
node was quickly bogged down such that Operators had trouble getting screens to
update. Even sites that had the very fast CP270's, if they had any Integrator
30's or gateways, the fastest_rsr had to remain fairly slow.
For sites where PI is used for off-platform study of trend displays by
engineers, you need to ensure that aliasing does not present a problem.
I do not know of any of the third-party packages that send data off platform
that do not use either FoxAPI or AIMAPI. It could be that some of the products
delivered by Alex Johnson used OMAPI in the past. OMAPI had a little more
flexibility when determining scan rates from the source stations.
Terry
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