800xA Property Transfer Definition limitations.
Is there a property or aspect limitation using the property transfer definition? I would like to bring 312 analogs (13 properties each) from PLC Connect to a function diagram via property transfer. Total properties transferred will be about 4000. I was planning on creating 1 property transfer aspect containg 13 properties per analog tag. I will make sure the update rates are offset for each transfer, will this cause any problems?
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Limitation is 1000 items with 100 items per second. You would need to create 4 seperate property transfer services.
In my experience with property transfer, you can not use it for time critical or control applications. Just for transfering non-critical values they work good. There will be occassional timeouts depending on load of OPC servers.
There are plenty of AKS threads on PT performance.
Performance is more or less what the destination OPC server and PLCs can cope with.
The [Workplace Structure]Web System Workplace:System Event and Operator Message Lists should be closely monitored while trying out the configuration.
It is indeed possible to overload the destination to the limit or beyond when regular operator interactions will become affected or made impossible.
- Choose data transfer via fieldbus if possible
- Keep a close eye on destination performance figures
- Do not transfer to General Properties, use SoftPoints
- Throttle write frequency to avoid overruns
- Verify that failover does not cause problems*
- Do not transfer interlocks, etc safeguarding equipment or human life.
- Current errorhandling will not echo all failures to above mentioned event lists. If you see one failed write assume there are more lost transfers "kept in the dark".
- I do not recognize 1000 items and 100 items/second as any typical limit. Its VERY hard to give accurate predictions, even with OPC server + PLC CPU & comms load figures available.
*) At PT service provider failover ALL properties will be transferred at once by the new master. Ensure destination can accept this flood.