OPC DA throughput (items per sec) per AC 800M Connectivity server
I checked the OPC Server for AC 800M -> tools -> Display OPC Statistics -> Data Access, but I understood it would be only the total of items (not items per seconds).
Where do I find this information?
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30.000 items per second (ips) is a LOT... not sure if that is a reliable figure...
It is not possible to view ips using the standard UI of System 800xA.
Search AKS for applog. The OpcDa Connector "Statistics" operation do output "item changes". With two subsequent executions (with some delay inbetween) you can calculate ips from the delta value.
A lot of underlying factors may limit the maximum reachable ips figure, eg controller load and limitations in MMS communications.
See this ips limit as the figure often appearing in "Vehicle Information" of premium cars; "Maximum speed is electronically limited to 250 km/hour". That speed is illegal in most countries and where so allowed, only on very "secure" roads built for that velocity.
Instead I recommend:
- Restrict controller cyclic load
- Limit intra-controller communication to a minimum.
- Rather use IAC than access variables.
- Slow down the module bus scanning to a minimum able to sustain the application
- Tune tasks to have ample amounts of Task Offset inbetween
- Avoid having too few (1) and too many (more than a handful and some) tasks.
- Ensure proper behaviour in OPC clients (Subscribe!, do not "scan")
- Restrict writing to a minimum
- Don't use strings in OPC unless its the only choice