Please specify redundant OPC comm. setup between third party DCS client to ABB800A system.What is OPC surrgate
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An OPC tunneler software removes the need to setup DCOM access permisson between the client and server. DCOM is a bit tricky and could leave security loop holes if not properly configured.
For asynchronous OPC, the Honeywell OPC client must also "trust" the 800xA server, or else the server callbacks with data to the client will not work.
Without a tunneler, you must find out if the Honeywell OPC client uses synchronous or asynchronous OPC. I have attached a document describing OPC client function calls.
If Honeywell uses asynchronous OPC, you must configure DCOM in both sides - likely four accounts are required. I have attached a second document that gives some advises.
Do not use the 800xA Service Account - create a dedicated account for the Honeywell client and set appropriate security permission on it.
By connecting the Honeywell clients to the connectivity servers, they will independently use the closest path to data and fall over to the other if first fail.