what does it mean for OPC heepfull system alram
Heap size is related to Memory size.
Prior to SV 5.1,The actual heap should be set to the size of the application but not exceed the Maximum recommended heap size. Check the OPC Server's About box after the Server is up running and make sure there is at least 30% spare heap.
Refer OPC Server Manual for more details.
From SV 5.1 onwards,Heap Size is set as default.