AfwDsOPCSurrogate - Active and inactive items found in the Applog viewer - need to know what it is referring to.
can any one advice me what is the log message referring to "4070 active + 4070 inactive". the below log was taken from the 800xA system 5.1 Applog viewer for AdvDsOPCConnection Statistics.
" Id: 1, BackendId: 0x034327B8, Node: 'EWS1', App: 'AfwDsOpcSurrogate', User: 'OPCAdmin', Items: 8140 (4070 active + 4070 inactive) "
***** Connector Statistics *****
Acc. num client connect: 8, last time: 11/17/2016 4:13:06 PM 178 ms
Acc. num client disconnect: 4, last time: 11/17/2016 4:13:00 PM 539 ms
Total number of connected clients: 4
Id: 0, BackendId: 0x00B29178, Node: 'EWS1', App: 'AdvHtHistorySrv', User: '800xAService', Items: 1788 (1788 active + 0 inactive)
Id: 0, BackendId: 0x00B32DD8, Node: 'EWS2', App: 'AdvHtHistorySrv', User: '800xAService', Items: 1788 (1788 active + 0 inactive)
Id: 1, BackendId: 0x034327B8, Node: 'EWS1', App: 'AfwDsOpcSurrogate', User: 'OPCAdmin', Items: 8140 (4070 active + 4070 inactive)
Id: 6, BackendId: 0x03CB2580, Node: 'EWS1', App: 'AfwWorkplaceApplication', User: 'Engineer', Items: 1017 (1017 active + 0 inactive)
Please study the OPC client connecting the OPC Surrogate!
The OPC DA interface allow an OPC client to add both "active" and "inactive" items.
- Active items will be automatically catered (cached) by the OPC server if the OPC group has an Update Rate set. If the OPC client has activated the asynchronous interface (called Advise()) the server will make automatic callbacks with updates on active items as they are changing. Client can also "ReadSyncFromCache".
- Inactive items will not be automatically cached, nor will any callbacks be made for them. The OPC client must post "ReadSync", "ReadAsync" or "Refresh" to force the OPC server to make roundtrip with the PLC.
Most OPC servers in the 800xA suite are best at handling active items over the asynchronous interface. This is the recommended client behavior.
I have attached an overview I use when teaching the E143 Troubleshooting System 800xA Expert Workshop.
I can not answer for why your client uses both active and inactive items - seems unneccesary and will if same just add overhead in form of memory and unneccesary OPC function calls.
Please consult the vendor of the OPC client.
Hint: for your own understanding please try the built-in "advdsopcclient.exe" of System 800xA - it allows studying each of these different OPC methods.