OPC Surrogate Process
How to know more about OPC surrogate process, very few words on documentation.
Which server is the ideal one(OPC Surrogate) to use for third party OPC connection if > 10,000 OPC items, because the OPC surrogate process runs on all the servers.
What is the practical limitation (no of OPC items) on one OPC surrogate process.
Document says maximum of 4 OPC surrogate process is it for the whole system or per server.
Please throw some light on this topic.
Voted best answer
OPC is always a difficult topic because many of look at just one end of it, the OPC server. The 800xA OPC Surrogate can run on any server but this depends on what you wish to do with the data. Data throughput rate (ie number of OPC items/sec) must be taken into account. This rate is driven not by the server but by the OPC client. Simply the OPC client establishes the link, create the (scan) groups and how offen to read the data. So to answer your question ask yourself this: what is the OPC client going to request? How offen? How many points (PV's)? Yes you are correct that one OPC Surrogate server can handle up to 10k points, however this is assuming you are doing nothing else with that server.
I would suggest with the numbers you are stating that you setup an 800xA Application server (ie a server that you add to the 800xA system) and allow the OPC clients only access to this server. This servers, as part of the standard 800xA system can "see" all tags within the system and therefore could (effectively) host or server all manner of data. Any issues associated with the OPC client, like asking for too much data, will only effect the 800xA application server and not the rest of the system. This way Opearions are kept safe.
Please ensure you understand any security concerns like: OPC DCOM, use of OPC tunnelers, security within the 800xA system by the OPC client (ie what can they access through an OPC session).
I have done very many OPC connetions with many different products and 800xA for customers and ABB people. The above is what I would say is good practice and has helped me with many projects all over the world.
I understand your frustrations as to lack of documentation, but as there are so many variables, no-one wants to write something that may not, under certain circumstances, be in-accurate or at least cause you (or your client) some issues.
OPC connections should not be taken lightly and as much as it can be used a panacea to solve all problems, OPC in of itself can cause even more.
Handled correctly OPC can help you with data access, control and information in a good way.
Should you need assistance, please contact your country's sales team, who can inturn contact regional presales to assist you further on this matter.