AC 800M OPC Server Limitation
I have a redundant connectivity server connected to AC 800M controllers. I would like to know if this connection would be regarded as "One" or "Two" Opc server subscription ?
As per the limitation, a maximum of 3 opc server can be connected to a AC 800M controller.
My requirement is to have a connection by two redundant connectivity server and another two AC 800M OPC server to be installed in a separate PC's to serve data to third party client system. If this configuration is valid ?
As far as I know, you need a separate license for each OPC server outside the one or two used to feed the 800xA system.
External subscribers can, if they like, subscribe via the OPC DA surrogate server available in all nodes belonging to an 800xA system, even though some overhead (security, etc) will apply then.
In your case, you need to order two (2) additional OPC server licenses.
I'm not sure the limit is only three...
I believe the limit is CPU load in the controllers. You can drive any AC 800M controller into CPU overload having just a single OPC server subscribing to it...
Make a good application (small tasks, with task offset in between each, sane amounts of inter-controller communication and not more than 50-55% cyclic load) and you can provide plenty of OPC data to several clients.
All boils down to CPU load and task tuning (cycle time, offset). Keep a watch on this and you can draw plenty of OPC data out of AC 800M controllers stretching from PM851 up to PM891 (the faster CPU, the more load it will carry, of course).